Maybe do a hex edit to the edited bois and have it say "ZERO". And if it turns out it had two places that say "256K" change just one and see if you see "ZERO" with no cache, or maybe it says "ZERO" when there really is cache memory present. In which case change "ZERO" to 256K" and "256K" to "ZERO"
@@Lilithe Actually, the string '256K' is not hardcded anywhere in the BIOS from what I can tell. Not even the digits "256" so they are doing something a bit sneakier and likely just changed the return value from the function that checks for cache to always be 256k.
I would err on the side of preservation. Submit it and see if it can be tagged as modified to show invalid cache levels. I'd love to see a hex diff of v1.2 and your v2.01 BIOS.
The Retro Web Team has accepted the BIOS and it is available for the board. Unfortunately, the two BIOSes are very different and I think a DIFF between them will most likely mark the entire file. Btw, I think there are some performance issues with version 2.01r. I have to look into this. You can see a huge difference in the moving benchmark between v1.2 and V2.01r.
@@bitsundbolts I'm pretty sure they just changed the None string to 256k. Back in the day in the 90's i had a 486 motherboard with fake chips that was reporting 256k. I've bougth myself 128k of cache and the BIOS was reporting 128k with real chips.
Yeah, that's what I'd expect. If I was them I'd search for "None" and overwrite with "256k". Perhaps you can do the reverse @bitsundbolts? Find 256k as a string, if you find two, change one to "None" and test, if it doesn't work, change the other instead.
The pinnacle of fake cache chips is a series of Socket 7 motherboards that we got here and had 4 black rectangle (QFP) chips with embossed "Write Back" on their plastic housing and the housing was just plain PVC with pins. Hilarious.
Yep, I had a 486 board (might've been a PCChips board, can't remember) with those "WriteBack" chips on it (normal dip package ones). Ami WinBios said something like '256kb Writeback Cache Enabled' on bootup, you could even switch the cache on and off in the bios, and the bootup reflected the change. Just a shame it was making no difference whatsoever!
@sierraboney1394 PC Chips M919. There were a few versions, I think. Some had the fake QFP packages soldered down. I have one that I bought new, back in the late 90s. It doesn't have those parts mounted, but has a proprietary Cache On A STick module (256kB) which is functional.
I have a 386 motherboard that came with fake cache chips. Not only that but they weren't socketed - they were soldered on the board. And had a doctored BIOS of course that showed "cache" on POST. I unsoldered those chips, installed sockets and real SRAM in them and it does have real cache now. I was lucky enough to find on ebay a number of years ago a large lot of SRAM cache chips that were NOS in tubes from a surplus lot so I have plenty of those. They are not the faster 15ns variety but rather 20ns, and still they work fine as cache in all motherboards I used them in.
@@bitsundbolts soldered fake cache is actually a lot more common than socketed. In fact it's one easy way to tell if a motherboard's cache is fake or not: if the chips are soldered, it's almost always fake. This is valid for DIP chips of course. While fake cache does exist on some Pentium motherboards, most of those use the QFP-package burst cache chips which are always soldered. For those, a way to tell if they have fake cache is different: if there are almost no traces leading from the "cache" chips to other components on the motherboard. :) They saved on copper to fake the chip connections.
Hahaha I see what they did with that BIOS. They didn't really want to deal with anything but the checksum so 2.0ra became 2.01r so they didn't have to shift any bytes and refactor.
All 386 and 486 bioses (and to certain extent pentium 1) are similar enough that you can easily go to retroweb and get latest bios based on your chipset. You don't have to pick bioses specific to your board. ;) (There are, of course, exceptions, though they are rare.) NB! I suggest checking out how to enable write-back on the cache, too. Another measurable performance jump. ;)
BIOS with double characters comes from 286 era, when there were two 8b chips (EVEN and ODD, or HI and LO) for a total 16b-wide ROM function. There was copyright repeated on both chips, hence the double characters. 486 supports bus sizing, so it can read 8b ROM (almost) directly, yet apparently the characters remained as they were before. There is an option in setup to turn on ROM's shadow (copy it into RAM), which speeds things up (32b access). When it's set ROM chip can be removed after boot with no effect, but don't try it 😉 Later BIOSes were compressed (more advanced), and they decompressed into RAM after power on, so those could be hot-swapped for flashing. Did that when computers were expensive, and programmers weren't actually cheap to get either.
That makes a lot of sense! Thanks for sharing. I am working on a 286 right now - which indeed has two BIOS chips (Hi/LO or EVEN/ODD). Thanks for clearing that up. Also, I did hot-swap a BIOS chip on an ASUS P3B in one of my videos! I never did that back then, but I wanted to try.
They were crap from start to finish, the fake cache chips looked fake and were made of some gharbage soft palstic you could dig a fingernail into. Shame as the chipset was pretty OK but the quality of the PCBs was just awful.
@@ms2649 Well, they didn't do the obvious thing and hard-code the string "256K" into the BIOS anywhere, so it must be hard-coded as a value somewhere. Unfortunately as a word value, it's 00 01 which shows up a billion times so it's hard to track down. I'm also not that experienced with Ghidra and it's doing some odd things that I can't figure out. I assumed the BIOS is either at FFFF:0000h or 000F:0000h but the code seems to have references to labels in the segment 0000:0000h so I'm not sure what the deal is there.
@@AureliusR things like cache checks are probably going to be the same across versions. what about using the older bios to search for where "NONE" is used, and then search for the bytes around that in the new bio. have you tried a good ol' diff on the versions?
I love finding these things at the scrapyard - each item seems to have some sort of story linked to it. I also didn't know they went to that extend to fake cache chips. But I am happy to hear that so many viewers are amazed how far those people went to make money.
It still happens, but now with modern Non-Volatile memory products. If you see a ridiculously high capacity medium sold at a ridiculously low price, they are fake. Your OS will show you that they have the capacity as shown by the label, but if you try to copy a (few) large file(s) to it, it will give you a write error. What's problematic is that this is occasionally also the case with media that are sold at regular prices for their stated capacity.
It’s likely possible to undo the modification to the bios. It’s a pretty safe bet the bare minimum was done to achieve the false reporting. There were probably only a few instructions modified, and with some disassembly it should be fairly simple to locate and undo it.
Yes, probably that is exactly what they did. I didn't try to reverse the change, but the BIOS is on The Retro Web if anyone would like to try. It also has a note about always displaying 256k of cache.
There is a complication to simply hex editing strings in the BIOS: you have to recalculate the checksum of the new file and write it in the right spot.
Another very interesting video =D I would upload that BIOS to the retro web anyway, with a readme that notes that the it will always report cache when not installed. Just based on the extra features that BIOS provides. That "mod" could probably be easily un-modded by someone if they can get a copy of the BIOS.
This was never a problem in North Korea because Kim Jong Un was a keen PC gamer and, when he found out about fake cache chips he asked his dad, Kim Jong Il to institute the death penalty for anyone caught selling them. Obviously the fact he was the only one in the country with a PC helped significantly with the scope of the enforcement needed.
A quick way to tell if there's any silicon inside a chip is to set your DMM to diode check mode and measure between Vcc and Gnd. With the black meter lead on the Vcc pin and the red meter lead on the Gnd pin you should be able to measure around 0.6 volts on an actual chip. Every chip has a reverse biased diode from Vcc to Gnd that's unintentionally made during doping.
I need to remember diode mode! It comes up very often and seems to be a super power :) Thanks for sharing! I will try that right away! OK, I checked! You are correct! Real chips show something between 0.6 to 0.7 volts. The fake chips show nothing (OL).
OMG. A few years ago I put together a Tomato 4DPS 486 system with a Am5x86-P100 that I stably overclocked to 200Mhz. If I remember correctly, the board could hold a whopping 512 K of cache. So I went and searched for cache chips and bought a bunch from few different sellers and sources. All of them were fake. I finally gave up on it.
Is it possible to install an amount of cache other than 256 or zero? It would be interesting to see if the BIOS is hacked to always display "256K" or would accurately enumerate other amounts.
I should be able to get 128K by using half the chips. But from what I understood from someone else that checked the BIOS file, it will continue to report 256K.
I came to know about motherboards with fake cache when I repaired a PC-Chips board. Mine had genuine cache but I wasn't aware that "fake cache" was an option! It amazes me, the picture you showed shows an IC coming from manufacturing, they just didn't add the actual die which is probably the expensive bit! Fantastic! And someone edited the BIOS from "None" to "256 KB", so simple and so hilarious! My first PC, a 386/DX 25 had no cache. I couldn't afford it. Imagine I paid big money (for a teenager in 1992) for cache and not even realise that the long awaited cache was just a piece of LEGO. I'd share the BIOS anyways, with a note explaining what it does :) For historic purposes :)
That is the sad part! You spend money because you want to have a better system - and then you realize that there is no difference. You would always be skeptical and claim that cache has no benefit: "I have seen it with my own eyes!" - Sad :( The BIOS is shared on The Retro Web for this board with a note that this BIOS always shows 256kb L2 cache.
The characters at the beginning of the BIOS are repeated to make sure that an intact copyright statement appears at the beginning of each ROM chip. For BIOSes designed for 16-bit processors, this usually means the characters are duplicated (in case there’s a low and high ROM chip), and BIOSes for 32-bit processors may be duplicated out quadrupled (in the event that four ROM chips was used).
That makes a lot of sense! Thanks for sharing this detail! I guess it was the cheaper method than properly preparing for 32-bit systems. Cutting corner as usual :)
At least the cache sockets were connected correctly, allowing real cache chips to be used, if they are using fake chips why go to the trouble of wiring up the sockets too?
Because they probably released versions with real cache too ! I have a pcchips m912 which came with real cache, even though they're known to use fake cache too
The fact there is no download on retroweb could be cause all of this versions are compromised. Like some scammers used to modify a bioses of the boards to sell em with fake chips (most likely as an assembled PC builds) and used to modify a version number/date so no one would guess to update it and fix the cache situation uncovering a scam. Maybe there is really no update.
Sounds reasonable. Though updating BIOS back then could be less than a smo0oth sailing experience, unless you have done it a few times. Most people didn't even bother to update bios or firmware because it could be risky due to software, hardware and procedural flaws. Nevertheless that would be a tactically sound method of covering the tracks and keeping them covered; until a user or developer who actually used the cache for a certain specific application noticed the difference, perhaps.
The fake chips are probably one of the reasons Intel and co started to embed cache in the processor itself. Not saying it's the only or even the most important reason, just that it's definitely one of them.
The main reason for integrating the cache is probably the speed advantage and production cost. It solved the fake cache problem as a positive side effect.
Haha Georg Schnurer from c't is an absolute legend, always worth a read! Still active, still core team, almost 30 years after this article. Also generally seen in c't videos, he's the cheerful guy. How much could they have saved by shipping fake chips? A couple dollars? 256k SRAM shouldn't be so expensive by mid 90s!
Yes! And I have an M919, but with the functional cache module fitted and the fake IC positions left empty. Currently it's running with AMD 5x86-133 and 64MB RAM.
I stock up on 256k cache chips from ebay recently and so far of the 50 I ordered I found only 2 bad ones. Unfortunately I remembered too late I could test them with my programmer (TL866CS) so I wasted a bit of time troubleshooting the board after installing all the chips... Seems fake chips were very typical back then, some motherboards with soldered ones didn't even have full packages and they literally had a hole on the bottom and completely bogus markings, for the socketed ones it seems they put a bit more effort to sell the lie. Also in some motherboards with soldered fake SMD chips you can literally see the traces going nowhere but in a loop between the fake chips
I had a little less luck with my order. Still, I have enough cache chips for experiments. I do agree, the chips that came on this board look real - they put real effort into it!
You mean with die materials so advanced is that they can't be seen nor touched. Apparently the Chinese found out ages ago, since Hans Christian Andersen relates the tale of a Chinese Emperor who was so rich that he could afford clothes made of this wondrous stuff...Or was that a fairy tale. Oh well, it's so long ago. It probably doesn't matter ;-).
Wish Id never heard of these bad chips, they were such a plague in the day! It's kind of why coast modules were far more reputable/reliable. After the PentiumPro, and integrating stuff onto the chip it was such a massive plus. Back in the day I did get a cheap 486sx since it had fake cache, it was unstable as heck, but dumping the chips it ran great.
Sorry you had to deal with fake cache back then. I agree, integrating the cache into the CPU stopped this method of cheating people. Then they started to fake entire CPUs... Even "new" (but fake) Ryzen CPUs are being sold these days with no die under the heat spreader.
@@bitsundbolts I had wondered if someone was going to start making ceramic slugs. I've bought motherboards and graphics cards that have mobile parts on them, but they don't try to pass them off as the real deal, but wow. I guess it's inevitable. that scammers got to scam.
True, that would be another way! But I think you probably need a thermal camera, or you need to wait until they heat up. But you are correct! I will try in the next video about those chips and BIOS.
I'd heard about fake cache chips back in the day, but I never came across them until the late 90s when I was working at a computer store. One day I was working on an old 486 machine when the older tech came in, pointed to the cache chips and said "Those are fake cache chips!". I was surprised and doubtful, so he told me to remove them and see what happens, so I did and it still reported 256K just like you saw. I asked what to do and he said just put them back, nobody ever asks about the cache, so they'll never know the difference. I did, but I wasn't happy about it. Looking back, there's not much you can do in those situations, other than offer a replacement machine if someone complains about buying one with fake cache. The boss was very dodgy, he definitely wouldn't go out of his way to buy new cache chips and replace them, especially considering it would probably cost more than the rest of the machine cost him!
I bet it's the same bios as on yhe website but they messed with yhe post and version string Snd replaced NONE with 256K You can try partially populating the slots and see if the amount changes... If do they left the check in place
That's redonkulous. The quick hex edit to change "none" to "256K" is the least surprising part, it's the empty sram dips that blows my mind. I mean really, how much extra revenue were they really generating with all this silliness?
About 20% of components I get off aliexpress are faulty, so if I order 10 mosfets, test them straight out of the packet, 2 go straight in the bin, still they arrive pretty fast these days.
I can't post comments here... they get auto-deleted... EDIT: I think i found the issue: a common word for getting software from the internet into your machine will autodelete your comment... (The word from timestamp of 9:35 )
Some comments just get deleted. Some are simply not shown, except when newest-first. I have seen a technical discussion thread in comments on intricacies of MPEG video compression where half of the 14 comments were hidden, namely all containing deeper technical insight! It has become very difficult to have actual conversation on here.
Under your profile, there is a "Your data in RUclips" section, where you can see all the comments you ever made. If it's not there, it got deleted. And mine did - i tried like 10 times, comment stayed for 10-15 seconds and then got deleted. Result is complete non-existence of the comment.
Absolutely - I've basically given up. I've tried to engage with people who are asking technical questions and there is no way to provide that info without the reply vanishing. If you can't say it in the reply in 5 words, it won't go through.
upload the bios with a note or description about being pulled from a fake cache chip mobo and always reports 256k. For posterity or analysis or lol's. ... lol,
OMG. I remember this board! I am fairly certain it was part of my only 486-PC. In the mid-2000s a firestation cleared out stuff they wanted to toss: aside some other less interesting stuff (a c64 with monitor meh... - I know, I'm committing sacrilege here^^) they gave me a HUGE Full Tower Case with an old 486 server or workstation. I am not sure anymore. I am fairly certain it was a lower megahertz (33 I think) Intel or AMD part. It had 2 HDDs: an 80 MB System Disk and a 120 MB Data-Disk. It had 8 MB of RAM and I'm fairly certain one of the hard drives was an SCSI one - there was a wide silvery cable, I couldn't identify then. They had Windows 3.11 for Workstations installed - I played a lot of Solitaire and Commander Keen on that Box - I'm not the shooter type so no Wolfenstein or Doom for me. I never bothered to look if the cache was fake When I moved from my parents for university I had to leave this treasure there. When they moved, they left it at their house... I have never seen it again and I am still really sad about it
I wonder if my 486 DX2 ever had any cache 🙈. It had an award bios…..version unknown. This is why we like RUclips consumer test channels….it keeps the vendors honest, or at least highlights what vendors do
Alls SRAM chips should work with the "generic" sram settings with that programmer. The sram pin layout is the same for all chips (28/32 pins) and the programmer is too slow to even outpace any sram chips so you can just look up the size of the chip if it is not present and use the corresponding generic profile (or winbond profile of same size).
They pocket the difference. A serious and organised crime when you think of the scale to make it worth getting all the equipment/ Just no chip is being fitted.
So far, my experience was mostly OK. Yes, I did get defective or fake products, but it was limited. It is the cheapest way for me to get access to chips if I don't find them at the scrapyard.
Fortunately my first motherboard in a 486 Zida 4DVS had real cache memory. I found this out when I installed another 256kb and the total was 512kb. However, I also had a PC Chips board which was famous for installing fake caches on motherboards and this one even had a special slot for a cache module, which I bought and...still the cache didn't work :)
I have one of those socket 3 boards with the strange looking cache module (I also have the module, but I don't know if it is fake or not). Unfortunately, the board is for repair and I wasn't able to fix it yet.
Thanks for this video!! Back around this time (1994) I bought a AMD 386 DX 40mhz motherboard at a computer fair and just buying 1mb of RAM was so expensive it cost more than the motherboard (CPU soldered on), Cache, OPL sound card, graphics card combined! It performed quite well, better than most 386s I see people using on youtube these days. I was able to play Doom on it at a decent frame rate with only a slightly downsized window. My friend had a 486 30mhz which played Doom slower, I wonder if the cache on his was fake?
On CuriousMarc they just heated the chips in a frying pan and chipped the plastic encasement off to see the die inside. A sharp wood chisel on the parting line above the legs should work.
Ha, you are lucky because you at least got some free copper in your fake chips 😃 I have fake chips that have absolutely nothing in them, not a single piece of metal. Also some infamous PC Chips boards have a BIOS that is modified in a much more complex way. Instead of just showing None/256K, when you have no/fake cache and a cache-related option enabled in BIOS, it shows a unique boot message that says "WRITE BACK CACHE ON" or something along those lines. Fortunately, the BIOS still works correctly with reals chips and even displays proper cache size (up to 1M). The model I'm talking about is M915i.
Interesting! So what, your cache chips have plastic pins? I guess my chips are one of the better (as in more expensive) fakes then. I have an M919 that needs to be repaired (CPU inserted in wrong orientation). I haven't figured out yet what the problem is. But I do have the cache memory that looks like a COASt module. But that might be fake too - who knows
@@bitsundbolts Oh no, the pins were metal, but they were barely inserted into the plastic and then there's nothing. In fact those "chips" were so bad they melted completely under a heat gun. As for M919, (to everyone who's reading this) plz never put regular COASt modules in there, also plz don't put modules with 3.3V SRAM chips if you use a 5V CPU. It will result in permanent damage.
well, you yourself admitted that you didn't have a proper chip type in the testing program for the suspicious chips and you successfully measured some resistance in them. why are you still calling them faulty? maybe they are good, but for other purposes than bios?
The chips that were on the motherboard did not have any resistance. I used faulty chips to show that there should be some resistance between some of the pins. The fake chips have no resistance anywhere which leads me to believe that there is no silicone chip embedded.
While I like your videos I found myself watching this at 1.5x speed. It's long and full of redundancy. Yes I've had fake cache chips on a 486, soldered in even.
This is likely due to the different default settings in the respective BIOSes, but look at how the "moving" performance shown in speedsys seems to be better for the first 8k of L1 cache on the older bios. I wonder why that is.
Yes, there are performance differences between the two BIOS versions. Looks like version 1.2 is better. However, the later BIOS has more features. I should look into this.
The real cache chips are plain SRAMs in a narrow DIP package; they're all pin compatible (otherwise they wouldn't work in the first place) so you can specify a pin compatible chip of similar speed grade in your tester, and it'll test it just fine. The fact that nothing works pretty much tells you right away that the ones you bought are fake.
I think a follow-up video where you tried to fix the fake BIOS would be interesting. Even if it ended up just being that the original "modders" just replaced the four bytes "None" with "256K" as others have suggested. I'm sure the location of the checksum in the BIOS and the algorithm is well documented somewhere on the web. If there aren't tools to correct the checksum I bet it would be easy to hack together a little Python script to do it. Or isn't there some tool for customizing Award modular BIOSes? I assume it can correct checksums. All of those topics would be interesting to see you cover I think.
I agree! They are all interesting topics. My experience in modding a BIOS is near zero, but it wouldn't be the first time I learn something new for this channel :)
That's appalling. You should track down the original seller and get some money back. Hopefully they are still in business and haven't moved or changed hands in the last 30 years.
Well, technically I bought this board from a scrapyard without a receipt. I don't think they would honor any warranty claim 😅 I understand that this hardware is useless by today's standards, but it's still fun to play around with it and learn.
I don't think they edited the output routines. They just removed the placeholder in the display string and replaced it with "256K" If you search the display string in the older bios and place that in the new bios, you only have to deal with checksum. There are checksum generators out to help you out. This could result in a correctly working newer bios.
Not only then, also today .... look out for the 10ns 128kb ISSI chips. Thise are 99.9% fake or relabeled 15ns chips. I also have some which are blanks like your chips. If you want to go 10ns: some modern 128k 10ns cache can be used (Cypress made some) which officially are 3.3v but have a tollerance up to 5.5v which can work but ymmv. You also need a interposer to make that work as they are not dip chips. I also have some 32k 8ns EliteMT ones which are really nice.
I have heard of those relabeling scams. It is unfortunate because it is probably very difficult to detect. Any idea how to spot/test relabeled chips? I would like to check the chips I got from AliExpress.
I had some 386 board back in the day with fake cache chips soldered in, not even socketed, so I assume the board maker was perfectly aware what they were doing (or some middle men added the chips). Those fake modules were visibly fake and had extremely "plasticky" feel. I assume they were completely empty plastics with legs because no BIOS or software would show any cache at all.
I found a computer next to a dumpster with a fake Pentium 200 that was a relabeled Pentium 100 but the BIOS also reported it as a Pentium 200 so I guess it was also modified. Until Windows XP, the system properties dialog did not display the CPU speed so it was fairly easy to hide the actual CPU speed from basic users who never used information and/or diagnostic programs.
I have an Asus board I bought where I suspect the BIOS was modified and fake cache chips are being used. I set the project aside several months ago to work on other projects because I couldn't figure out why all tests showed only one cache, including CACEHCHK and SpeedSys from the Phil's DOS Benchmark Pack. With this video, I'm curious if I am running in to a similar situation like what you experienced here. Unfortunately I don't have a chip tester or EPROM burner to troubleshoot.
You should be able to use a multimeter (if you have one). It just confirms if the legs on the chips connect to something internally. Otherwise, having a strange behavior in CACHECHK or SpeedSys may be an indicator, but it could be that the cache is just faulty. I think the best method would be a multimeter.
I had the exact same thought. They probably took the stock BIOS, searched for "None" and replaced it with "256K" and put the empty chips in the board. I would upload a copy of it to the Retro Web as-is, and a copy where you search for 256K in the file, replace it with "None", test it, and upload it too.
Sadly, not unheard of. I have a pentium 90 motherboard with fake cache chips. Unfortunately they are surface mounted so I can't change them. Great video, keep up the excellent work 👍👍
Yeah, this is even one step ahead of the famous PCChips Boards with fake "write back" cache. I have two of this M919 Baords. One green PCB with the plastic fake chips and traces to a roundabout and a later version without the chips but with the right cache modul and real 256kB. There are also fake chips with marking and legs but they are hollow on the underside.
I have one of those M919 boards that needs to be repaired. The CPU was inserted in a wrong orientation and blew up the socket. Crazy to hear all those stories about fake cache chips and the extend!
I have seen some of the fake chips made of plastic, not epoxy. You can melt them with a soldering iron. I was really suprised, I have never seen this before.
Wow! I think these ones have an epoxy body - at least they felt like it. I did not put a soldering iron close to them yet. But maybe we will open one of them.
I have a 486 board that had fake cache chips installed and modified BIOS too. I replaced the cache chips and now I have working L2 cache, but I never updated the BIOS. It seems that the amount of cache shown and the option to switch on/off external cache has been modified, but the cache itself works correctly when the appropiate chips are installed 😅
Oh, I did not test the BIOS setting to switch off the cache. That would be interesting to test how well the BIOS hack was implemented. But I have a feeling that it might report correctly as NONE when "External Cache" is turned off in the BIOS since it probably accesses a different routine in the BIOS.
You can take the chips to a dentist. Nowadays most dentists have digital X-Ray machines. They have a good resolution and can look into the chips without any damage. I do that pretty often, usually reverse engineering sealed obsolete modules to fix old machines. You can't see what is exactly on a chip but you can clearly see if there is a real chip inside.
Haha, I don't know what my dentist would tell me if I show up with a bag of chips for him to put in his X-Ray machine :) I can only imagine the look on his face (before he kicks me out) :)
There's a "notes" field in TRW's ROM section. A perfectly fine place to put a note that "this BIOS reports fake 256k cache", and it can still be put there for all to gawk at the nasty shenanigans. Regardless of whether it was an evil thing to have done by the manufacturer, it is still part of history.
I remember this from around when I started building my own PCs around 1993. Without access to the Internet or much in the way of peer help, This rubbish convinced me that Cache made no difference for years.
Oh wow! That is what I wrote in an answer to someone else! EXACTLY! If you see this, you definitely will say that! Crazy - I am sorry that you were misled by this.
Your bios version is 4.50g in both cases ..What you read is known as info text . The fake bios may not have nothing new or improved, but tish infotext and date changed.
Both BIOSes are quire different. I will show that in an upcoming video. I think the 4.50g might be the AWARD main version. 1.2 and 2.01r is probably for the content of the BIOS (could be very different from board to board or even from version to version). I remember that v4.50 and v6 makes a big difference when modifying BIOS logos that appear on the screen (Energy Star Logo).
“None” and “256K” are both exactly 4 characters long. The simplest hex edit in the world.
I had the exact same thought. They probably took the stock BIOS, searched for "None" and replaced it with "256K" and put the empty chips in the board.
Maybe do a hex edit to the edited bois and have it say "ZERO". And if it turns out it had two places that say "256K" change just one and see if you see "ZERO" with no cache, or maybe it says "ZERO" when there really is cache memory present. In which case change "ZERO" to 256K" and "256K" to "ZERO"
Isn't there a program that displays both bios side by side and highlights the differences in red, ie, seen it somewhere.
@@SidneyCritic They are different versions - so there will be a LOT of differences
@@Lilithe Actually, the string '256K' is not hardcded anywhere in the BIOS from what I can tell. Not even the digits "256" so they are doing something a bit sneakier and likely just changed the return value from the function that checks for cache to always be 256k.
I would err on the side of preservation. Submit it and see if it can be tagged as modified to show invalid cache levels.
I'd love to see a hex diff of v1.2 and your v2.01 BIOS.
The Retro Web Team has accepted the BIOS and it is available for the board. Unfortunately, the two BIOSes are very different and I think a DIFF between them will most likely mark the entire file.
Btw, I think there are some performance issues with version 2.01r. I have to look into this. You can see a huge difference in the moving benchmark between v1.2 and V2.01r.
@@bitsundbolts I'm pretty sure they just changed the None string to 256k. Back in the day in the 90's i had a 486 motherboard with fake chips that was reporting 256k. I've bougth myself 128k of cache and the BIOS was reporting 128k with real chips.
Yeah, that's what I'd expect. If I was them I'd search for "None" and overwrite with "256k". Perhaps you can do the reverse @bitsundbolts? Find 256k as a string, if you find two, change one to "None" and test, if it doesn't work, change the other instead.
That's what I was thinking.
Search the Rom for 256kb.
Replace with none.
That's what I was thinking.
Search the Rom for 256kb.
Replace with none.
Excellent stuff, I should look at my board may have a similar issue or I have rose tinted glasses around how well Doom used to play on a 486! :)
I guess it's good practice to test the cache on any board. Based on what I saw with this board, you can't trust any values displayed.
maybe this is the cause for lgr s woodgrain being so slow 😂
Top of the article is dated 95 not 2000. The way back image date is 2000. Thanks for another video!
yeah i have the physical copy of the magazine right here, it´s from march 1995
Yes, you're right, my bad.
@@bitsundbolts is there a private area or discord?
I just recently set up a discord server. I will publish a link soon on my website.
who was even interested 486 in 2000 :)
The pinnacle of fake cache chips is a series of Socket 7 motherboards that we got here and had 4 black rectangle (QFP) chips with embossed "Write Back" on their plastic housing and the housing was just plain PVC with pins. Hilarious.
Yep, I had a 486 board (might've been a PCChips board, can't remember) with those "WriteBack" chips on it (normal dip package ones). Ami WinBios said something like '256kb Writeback Cache Enabled' on bootup, you could even switch the cache on and off in the bios, and the bootup reflected the change. Just a shame it was making no difference whatsoever!
@sierraboney1394 PC Chips M919. There were a few versions, I think. Some had the fake QFP packages soldered down. I have one that I bought new, back in the late 90s. It doesn't have those parts mounted, but has a proprietary Cache On A STick module (256kB) which is functional.
I have a 386 motherboard that came with fake cache chips. Not only that but they weren't socketed - they were soldered on the board. And had a doctored BIOS of course that showed "cache" on POST. I unsoldered those chips, installed sockets and real SRAM in them and it does have real cache now. I was lucky enough to find on ebay a number of years ago a large lot of SRAM cache chips that were NOS in tubes from a surplus lot so I have plenty of those. They are not the faster 15ns variety but rather 20ns, and still they work fine as cache in all motherboards I used them in.
Wow, that's a commitment to fake cache! They saved even on the sockets!
@@bitsundbolts soldered fake cache is actually a lot more common than socketed. In fact it's one easy way to tell if a motherboard's cache is fake or not: if the chips are soldered, it's almost always fake. This is valid for DIP chips of course. While fake cache does exist on some Pentium motherboards, most of those use the QFP-package burst cache chips which are always soldered. For those, a way to tell if they have fake cache is different: if there are almost no traces leading from the "cache" chips to other components on the motherboard. :) They saved on copper to fake the chip connections.
Hahaha I see what they did with that BIOS. They didn't really want to deal with anything but the checksum so 2.0ra became 2.01r so they didn't have to shift any bytes and refactor.
All 386 and 486 bioses (and to certain extent pentium 1) are similar enough that you can easily go to retroweb and get latest bios based on your chipset. You don't have to pick bioses specific to your board. ;) (There are, of course, exceptions, though they are rare.)
NB! I suggest checking out how to enable write-back on the cache, too. Another measurable performance jump. ;)
I want to try that some day. Using BIOSes from different boards. Good to know, I'll keep it in mind. Thanks!
Definitely, as long as the chipset is the same it's easy, used to do that back when these boards were new.
BIOS with double characters comes from 286 era, when there were two 8b chips (EVEN and ODD, or HI and LO) for a total 16b-wide ROM function. There was copyright repeated on both chips, hence the double characters. 486 supports bus sizing, so it can read 8b ROM (almost) directly, yet apparently the characters remained as they were before. There is an option in setup to turn on ROM's shadow (copy it into RAM), which speeds things up (32b access). When it's set ROM chip can be removed after boot with no effect, but don't try it 😉 Later BIOSes were compressed (more advanced), and they decompressed into RAM after power on, so those could be hot-swapped for flashing. Did that when computers were expensive, and programmers weren't actually cheap to get either.
That makes a lot of sense! Thanks for sharing. I am working on a 286 right now - which indeed has two BIOS chips (Hi/LO or EVEN/ODD). Thanks for clearing that up. Also, I did hot-swap a BIOS chip on an ASUS P3B in one of my videos! I never did that back then, but I wanted to try.
Old guy here again, I vaguely recall a scandal regarding fake cache chips back in the 90s
How about "experienced" 😊? Even though I'm aware of fake cache, I don't think I knew it back then.
Fake cache was a real problem, and ruined PCChips reputation as their boards started shipping that way too. Kind of sad.
I do have one of those boards. It has solder pads, but the traces route from one cache chip to another - no traces go anywhere else.
@@bitsundbolts Begs the question, what were they thinking...
Ah PCChips - the Maxtor of motherboards.
I think I remember seeing a video where the cache chips were hollow...
EDIT: Speaking of the devil 25:53
They were crap from start to finish, the fake cache chips looked fake and were made of some gharbage soft palstic you could dig a fingernail into.
Shame as the chipset was pretty OK but the quality of the PCBs was just awful.
Can you please upload your dump of the original BIOS somewhere? I would like to process it through Ghidra
It is already on The Retro Web for this board. It has a note to always show 256kb of cache
Mind keeping us updated with what you find?
@@ms2649 Well, they didn't do the obvious thing and hard-code the string "256K" into the BIOS anywhere, so it must be hard-coded as a value somewhere. Unfortunately as a word value, it's 00 01 which shows up a billion times so it's hard to track down. I'm also not that experienced with Ghidra and it's doing some odd things that I can't figure out. I assumed the BIOS is either at FFFF:0000h or 000F:0000h but the code seems to have references to labels in the segment 0000:0000h so I'm not sure what the deal is there.
@@AureliusR things like cache checks are probably going to be the same across versions.
what about using the older bios to search for where "NONE" is used, and then search for the bytes around that in the new bio.
have you tried a good ol' diff on the versions?
That's a pretty wild discovery. I've heard of fake cache chips, but a BIOS apparently designed to lie to you about it is something else entirely.
I love finding these things at the scrapyard - each item seems to have some sort of story linked to it. I also didn't know they went to that extend to fake cache chips. But I am happy to hear that so many viewers are amazed how far those people went to make money.
It still happens, but now with modern Non-Volatile memory products. If you see a ridiculously high capacity medium sold at a ridiculously low price, they are fake. Your OS will show you that they have the capacity as shown by the label, but if you try to copy a (few) large file(s) to it, it will give you a write error.
What's problematic is that this is occasionally also the case with media that are sold at regular prices for their stated capacity.
It’s likely possible to undo the modification to the bios. It’s a pretty safe bet the bare minimum was done to achieve the false reporting. There were probably only a few instructions modified, and with some disassembly it should be fairly simple to locate and undo it.
The absolute bare minimum is to change the string if zero.
@@myne00 probably needs confirmation but yeah my first assumption is that they've replaced the "none" string with "256kb"
Yes, probably that is exactly what they did. I didn't try to reverse the change, but the BIOS is on The Retro Web if anyone would like to try. It also has a note about always displaying 256k of cache.
There is a complication to simply hex editing strings in the BIOS: you have to recalculate the checksum of the new file and write it in the right spot.
Not a huge deal though.@@stamasd8500
This brings back memories. Also of the time when they used to put parity generators on the RAM PCBs instead of real RAM parity chips.
Another very interesting video =D I would upload that BIOS to the retro web anyway, with a readme that notes that the it will always report cache when not installed. Just based on the extra features that BIOS provides. That "mod" could probably be easily un-modded by someone if they can get a copy of the BIOS.
It is on the wiki
This was never a problem in North Korea because Kim Jong Un was a keen PC gamer and, when he found out about fake cache chips he asked his dad, Kim Jong Il to institute the death penalty for anyone caught selling them. Obviously the fact he was the only one in the country with a PC helped significantly with the scope of the enforcement needed.
A quick way to tell if there's any silicon inside a chip is to set your DMM to diode check mode and measure between Vcc and Gnd. With the black meter lead on the Vcc pin and the red meter lead on the Gnd pin you should be able to measure around 0.6 volts on an actual chip. Every chip has a reverse biased diode from Vcc to Gnd that's unintentionally made during doping.
Didn’t know that. That’s quite interesting and useful to know.
I need to remember diode mode! It comes up very often and seems to be a super power :) Thanks for sharing! I will try that right away! OK, I checked! You are correct! Real chips show something between 0.6 to 0.7 volts. The fake chips show nothing (OL).
OMG.
A few years ago I put together a Tomato 4DPS 486 system with a Am5x86-P100 that I stably overclocked to 200Mhz.
If I remember correctly, the board could hold a whopping 512 K of cache. So I went and searched for cache chips and bought a bunch from few different sellers and sources.
All of them were fake.
I finally gave up on it.
Wow, a stable overclock to 200 MHz is not that common! Congrats! Sorry on all the fake cache chips you collected :(
Glad you are good enough to cache this problem.
😂
Is it possible to install an amount of cache other than 256 or zero?
It would be interesting to see if the BIOS is hacked to always display "256K" or would accurately enumerate other amounts.
I should be able to get 128K by using half the chips. But from what I understood from someone else that checked the BIOS file, it will continue to report 256K.
I came to know about motherboards with fake cache when I repaired a PC-Chips board. Mine had genuine cache but I wasn't aware that "fake cache" was an option!
It amazes me, the picture you showed shows an IC coming from manufacturing, they just didn't add the actual die which is probably the expensive bit! Fantastic!
And someone edited the BIOS from "None" to "256 KB", so simple and so hilarious!
My first PC, a 386/DX 25 had no cache. I couldn't afford it. Imagine I paid big money (for a teenager in 1992) for cache and not even realise that the long awaited cache was just a piece of LEGO.
I'd share the BIOS anyways, with a note explaining what it does :) For historic purposes :)
That is the sad part! You spend money because you want to have a better system - and then you realize that there is no difference. You would always be skeptical and claim that cache has no benefit: "I have seen it with my own eyes!" - Sad :(
The BIOS is shared on The Retro Web for this board with a note that this BIOS always shows 256kb L2 cache.
The characters at the beginning of the BIOS are repeated to make sure that an intact copyright statement appears at the beginning of each ROM chip. For BIOSes designed for 16-bit processors, this usually means the characters are duplicated (in case there’s a low and high ROM chip), and BIOSes for 32-bit processors may be duplicated out quadrupled (in the event that four ROM chips was used).
That makes a lot of sense! Thanks for sharing this detail! I guess it was the cheaper method than properly preparing for 32-bit systems. Cutting corner as usual :)
Maybe they replace the String "NONE" with "256K" in on fake Bios
That is probably what they have done. It's the quickest and easiest way to get this done.
At least the cache sockets were connected correctly, allowing real cache chips to be used, if they are using fake chips why go to the trouble of wiring up the sockets too?
Because they probably released versions with real cache too !
I have a pcchips m912 which came with real cache, even though they're known to use fake cache too
I assume the board was made by a reputable manufacturer, but the vendor put in the fake chips and modified bios.
@@TheaH2O2 the manufacturer is probably complicit, like I said, I've seen that with pcchips too, and they're definitely scammers :D
The fact there is no download on retroweb could be cause all of this versions are compromised. Like some scammers used to modify a bioses of the boards to sell em with fake chips (most likely as an assembled PC builds) and used to modify a version number/date so no one would guess to update it and fix the cache situation uncovering a scam. Maybe there is really no update.
Sounds reasonable. Though updating BIOS back then could be less than a smo0oth sailing experience, unless you have done it a few times. Most people didn't even bother to update bios or firmware because it could be risky due to software, hardware and procedural flaws. Nevertheless that would be a tactically sound method of covering the tracks and keeping them covered; until a user or developer who actually used the cache for a certain specific application noticed the difference, perhaps.
The fake chips are probably one of the reasons Intel and co started to embed cache in the processor itself. Not saying it's the only or even the most important reason, just that it's definitely one of them.
The main reason for integrating the cache is probably the speed advantage and production cost. It solved the fake cache problem as a positive side effect.
Haha Georg Schnurer from c't is an absolute legend, always worth a read! Still active, still core team, almost 30 years after this article. Also generally seen in c't videos, he's the cheerful guy.
How much could they have saved by shipping fake chips? A couple dollars? 256k SRAM shouldn't be so expensive by mid 90s!
There was definitely criminal energy behind all this - I wonder too if this was lucrative.
Georg Schnurer is a legend. He worked at the c't Magazine.
Worked? Works! He carries vaguely half the magazine on his back basically now, 30 years later.
well...that was interesting (imagine it said in Seinfeld's voice). those RAM modules that you made look sick
Nice discovery. I wonder if it would be possible to build an interposer board to use modurn sram chips and give it an ungodly amount of cache :D
I think the cache is probably limited by the board. I think it won't go beyond 256k.
Having longer sockets for some of the cache chips on this board I assume that it could take 512Mbit chips and have more than 256KB of cache?
In theory, yes. But I haven't checked.
PCChips M912 and M919 - notorious fake cache boards, but superb performers
Yes! And I have an M919, but with the functional cache module fitted and the fake IC positions left empty. Currently it's running with AMD 5x86-133 and 64MB RAM.
I stock up on 256k cache chips from ebay recently and so far of the 50 I ordered I found only 2 bad ones. Unfortunately I remembered too late I could test them with my programmer (TL866CS) so I wasted a bit of time troubleshooting the board after installing all the chips...
Seems fake chips were very typical back then, some motherboards with soldered ones didn't even have full packages and they literally had a hole on the bottom and completely bogus markings, for the socketed ones it seems they put a bit more effort to sell the lie.
Also in some motherboards with soldered fake SMD chips you can literally see the traces going nowhere but in a loop between the fake chips
I had a little less luck with my order. Still, I have enough cache chips for experiments.
I do agree, the chips that came on this board look real - they put real effort into it!
After this video is completed these chips deserve a thorough Widlarizing.
I guess... I need to get... A SLEDGEHAMMER!
This was obviously just experimentation with early "stealth" chips.
Where?
You mean with die materials so advanced is that they can't be seen nor touched. Apparently the Chinese found out ages ago, since Hans Christian Andersen relates the tale of a Chinese Emperor who was so rich that he could afford clothes made of this wondrous stuff...Or was that a fairy tale. Oh well, it's so long ago. It probably doesn't matter ;-).
Wish Id never heard of these bad chips, they were such a plague in the day! It's kind of why coast modules were far more reputable/reliable. After the PentiumPro, and integrating stuff onto the chip it was such a massive plus. Back in the day I did get a cheap 486sx since it had fake cache, it was unstable as heck, but dumping the chips it ran great.
Sorry you had to deal with fake cache back then. I agree, integrating the cache into the CPU stopped this method of cheating people. Then they started to fake entire CPUs... Even "new" (but fake) Ryzen CPUs are being sold these days with no die under the heat spreader.
@@bitsundbolts I had wondered if someone was going to start making ceramic slugs. I've bought motherboards and graphics cards that have mobile parts on them, but they don't try to pass them off as the real deal, but wow. I guess it's inevitable. that scammers got to scam.
Btw you can always just check if they get warm
True, that would be another way! But I think you probably need a thermal camera, or you need to wait until they heat up. But you are correct! I will try in the next video about those chips and BIOS.
@@bitsundbolts I don't do much with 486 boards but the one I have the cash ic do get pretty toasty after a while so yeah it's a viable method
2.01r. R is for ripoff :). This is a really fascinating video. Still watching - thanks for posting this!
"...these chips are completely empty."
No. There are NO chips in those DIPs. The "chip" part relates to the silicon inside the package.
At least you don't have fake cache sockets (with fake traces that go nowhere). Those were even MORE despicable! 😀
It could be interesting drilling them and looking what's inside of those fake chips.
Fascinating (and heart breaking). I very much liked your use of the Programmer to test the chips.
I'd heard about fake cache chips back in the day, but I never came across them until the late 90s when I was working at a computer store. One day I was working on an old 486 machine when the older tech came in, pointed to the cache chips and said "Those are fake cache chips!". I was surprised and doubtful, so he told me to remove them and see what happens, so I did and it still reported 256K just like you saw. I asked what to do and he said just put them back, nobody ever asks about the cache, so they'll never know the difference. I did, but I wasn't happy about it. Looking back, there's not much you can do in those situations, other than offer a replacement machine if someone complains about buying one with fake cache. The boss was very dodgy, he definitely wouldn't go out of his way to buy new cache chips and replace them, especially considering it would probably cost more than the rest of the machine cost him!
I bet it's the same bios as on yhe website but they messed with yhe post and version string
Snd replaced NONE with 256K
You can try partially populating the slots and see if the amount changes... If do they left the check in place
Guess the fake chips are still better than broken ones, since they don't mess with anything by being there.
That's redonkulous. The quick hex edit to change "none" to "256K" is the least surprising part, it's the empty sram dips that blows my mind. I mean really, how much extra revenue were they really generating with all this silliness?
This is why I stuck to brand name machines for my personal collection of computers - my DX/4 is a SIemens Nixdorf, and the cache is real ;)
In the words of Senator Vreenak, "IT'S A FAAAAAAAAAAKE!!!!"
I have 2 of these MV035 boards, one I purchased when they were new. This is interesting.
About 20% of components I get off aliexpress are faulty, so if I order 10 mosfets, test them straight out of the packet, 2 go straight in the bin, still they arrive pretty fast these days.
Not fake, just hardened against cache timing attacks!
Yeah... I'd suggest trying to patch the BIOS and upload it, since it seems legit enough otherwise.
I can't post comments here... they get auto-deleted...
EDIT: I think i found the issue: a common word for getting software from the internet into your machine will autodelete your comment... (The word from timestamp of 9:35 )
Wrong
I'm sorry. Yes, RUclips does delete comments. Sometimes, I might get them for "review", but most of the time, comments are just deleted automatically.
Some comments just get deleted. Some are simply not shown, except when newest-first. I have seen a technical discussion thread in comments on intricacies of MPEG video compression where half of the 14 comments were hidden, namely all containing deeper technical insight! It has become very difficult to have actual conversation on here.
Under your profile, there is a "Your data in RUclips" section, where you can see all the comments you ever made. If it's not there, it got deleted. And mine did - i tried like 10 times, comment stayed for 10-15 seconds and then got deleted. Result is complete non-existence of the comment.
Absolutely - I've basically given up. I've tried to engage with people who are asking technical questions and there is no way to provide that info without the reply vanishing. If you can't say it in the reply in 5 words, it won't go through.
The replicated copyright comes from the time when you had an ODD and EVEN BIOS chip, so the complete copyright appears in each chip image.
The hacked v2.01 bios that came with the board tested with lower overall read/move speeds than the v1.2 bios you tested on it.
I did notice that! 1.2 is quite a bit faster, but it has less features. Something for a follow-up video.
upload the bios with a note or description about being pulled from a fake cache chip mobo and always reports 256k. For posterity or analysis or lol's.
...
lol,
OMG. I remember this board! I am fairly certain it was part of my only 486-PC. In the mid-2000s a firestation cleared out stuff they wanted to toss: aside some other less interesting stuff (a c64 with monitor meh... - I know, I'm committing sacrilege here^^) they gave me a HUGE Full Tower Case with an old 486 server or workstation. I am not sure anymore. I am fairly certain it was a lower megahertz (33 I think) Intel or AMD part. It had 2 HDDs: an 80 MB System Disk and a 120 MB Data-Disk. It had 8 MB of RAM and I'm fairly certain one of the hard drives was an SCSI one - there was a wide silvery cable, I couldn't identify then. They had Windows 3.11 for Workstations installed - I played a lot of Solitaire and Commander Keen on that Box - I'm not the shooter type so no Wolfenstein or Doom for me. I never bothered to look if the cache was fake When I moved from my parents for university I had to leave this treasure there. When they moved, they left it at their house... I have never seen it again and I am still really sad about it
I wonder if my 486 DX2 ever had any cache 🙈. It had an award bios…..version unknown. This is why we like RUclips consumer test channels….it keeps the vendors honest, or at least highlights what vendors do
Alls SRAM chips should work with the "generic" sram settings with that programmer. The sram pin layout is the same for all chips (28/32 pins) and the programmer is too slow to even outpace any sram chips so you can just look up the size of the chip if it is not present and use the corresponding generic profile (or winbond profile of same size).
They pocket the difference. A serious and organised crime when you think of the scale to make it worth getting all the equipment/ Just no chip is being fitted.
I'm like 100% sure I built a system in high school with these chips.
This is 1906 technology 😪
They were at least not soldered to the board... ;)
In bios code changed none on 256k🙂
I would *never* trust any products from AliExpress or Temu or any other Chinese sellers.
So far, my experience was mostly OK. Yes, I did get defective or fake products, but it was limited. It is the cheapest way for me to get access to chips if I don't find them at the scrapyard.
Fortunately my first motherboard in a 486 Zida 4DVS had real cache memory. I found this out when I installed another 256kb and the total was 512kb. However, I also had a PC Chips board which was famous for installing fake caches on motherboards and this one even had a special slot for a cache module, which I bought and...still the cache didn't work :)
I have one of those socket 3 boards with the strange looking cache module (I also have the module, but I don't know if it is fake or not). Unfortunately, the board is for repair and I wasn't able to fix it yet.
Use plyers and open them
Thanks for this video!! Back around this time (1994) I bought a AMD 386 DX 40mhz motherboard at a computer fair and just buying 1mb of RAM was so expensive it cost more than the motherboard (CPU soldered on), Cache, OPL sound card, graphics card combined! It performed quite well, better than most 386s I see people using on youtube these days. I was able to play Doom on it at a decent frame rate with only a slightly downsized window. My friend had a 486 30mhz which played Doom slower, I wonder if the cache on his was fake?
I meant 33mhz not 30mhz. LOL.
What happens if you install 128kb of cache? Does it still say 256kb?
Based on what I've heard, yes. But I will investigate further.
On CuriousMarc they just heated the chips in a frying pan and chipped the plastic encasement off to see the die inside.
A sharp wood chisel on the parting line above the legs should work.
I will open one of those chips. I don't have the proper tools, but I might just go at it for about 10 minutes with sanding paper...
The fake chips aren’t even electrically connected. They’re invisible because they can’t even make a circuit.
Yes, it is as if nothing is in those sockets.
Ha, you are lucky because you at least got some free copper in your fake chips 😃 I have fake chips that have absolutely nothing in them, not a single piece of metal. Also some infamous PC Chips boards have a BIOS that is modified in a much more complex way. Instead of just showing None/256K, when you have no/fake cache and a cache-related option enabled in BIOS, it shows a unique boot message that says "WRITE BACK CACHE ON" or something along those lines. Fortunately, the BIOS still works correctly with reals chips and even displays proper cache size (up to 1M). The model I'm talking about is M915i.
Interesting! So what, your cache chips have plastic pins? I guess my chips are one of the better (as in more expensive) fakes then. I have an M919 that needs to be repaired (CPU inserted in wrong orientation). I haven't figured out yet what the problem is. But I do have the cache memory that looks like a COASt module. But that might be fake too - who knows
@@bitsundbolts Oh no, the pins were metal, but they were barely inserted into the plastic and then there's nothing. In fact those "chips" were so bad they melted completely under a heat gun. As for M919, (to everyone who's reading this) plz never put regular COASt modules in there, also plz don't put modules with 3.3V SRAM chips if you use a 5V CPU. It will result in permanent damage.
Super information video thank you sir :)
Welcome! I'm happy that you like the video!
I had 486 board with AMD 486 overclocked to 133Mhz and it had these fake chips installed. Doom sucked on that setup
Ohhh - a high-end 486 system with fake cache :( very sad and I can imagine that some games were horribly slow!
Why not run speedsys with the fake chips and fake bios
There seems to be a measurable performance difference between those two BIOS versions. Maybe I should test that as you said.
well, you yourself admitted that you didn't have a proper chip type in the testing program for the suspicious chips and you successfully measured some resistance in them. why are you still calling them faulty? maybe they are good, but for other purposes than bios?
The chips that were on the motherboard did not have any resistance. I used faulty chips to show that there should be some resistance between some of the pins. The fake chips have no resistance anywhere which leads me to believe that there is no silicone chip embedded.
While I like your videos I found myself watching this at 1.5x speed. It's long and full of redundancy. Yes I've had fake cache chips on a 486, soldered in even.
I'll try to reduce redundancy. Thanks for letting me know.
Cache chips with a catch.
You could X ray chip. I worked in chip design and failure analysis could give us X ray image to show bonding problems, and occasionally a missing die.
That would be really nice, but I do not have access to an X-Ray device. I probably have to sand the body down.
This is likely due to the different default settings in the respective BIOSes, but look at how the "moving" performance shown in speedsys seems to be better for the first 8k of L1 cache on the older bios. I wonder why that is.
Yes, there are performance differences between the two BIOS versions. Looks like version 1.2 is better. However, the later BIOS has more features. I should look into this.
The real cache chips are plain SRAMs in a narrow DIP package; they're all pin compatible (otherwise they wouldn't work in the first place) so you can specify a pin compatible chip of similar speed grade in your tester, and it'll test it just fine. The fact that nothing works pretty much tells you right away that the ones you bought are fake.
Well, I didn't buy the fake chips. They came on the motherboard I found at the scrapyard.
I think a follow-up video where you tried to fix the fake BIOS would be interesting. Even if it ended up just being that the original "modders" just replaced the four bytes "None" with "256K" as others have suggested.
I'm sure the location of the checksum in the BIOS and the algorithm is well documented somewhere on the web. If there aren't tools to correct the checksum I bet it would be easy to hack together a little Python script to do it.
Or isn't there some tool for customizing Award modular BIOSes? I assume it can correct checksums.
All of those topics would be interesting to see you cover I think.
I agree! They are all interesting topics. My experience in modding a BIOS is near zero, but it wouldn't be the first time I learn something new for this channel :)
That's appalling. You should track down the original seller and get some money back. Hopefully they are still in business and haven't moved or changed hands in the last 30 years.
Well, technically I bought this board from a scrapyard without a receipt. I don't think they would honor any warranty claim 😅
I understand that this hardware is useless by today's standards, but it's still fun to play around with it and learn.
Vintagefake
I don't think they edited the output routines. They just removed the placeholder in the display string and replaced it with "256K" If you search the display string in the older bios and place that in the new bios, you only have to deal with checksum. There are checksum generators out to help you out. This could result in a correctly working newer bios.
I will look into this! I already have more than enough material from the comments to make another video!
Not only then, also today .... look out for the 10ns 128kb ISSI chips. Thise are 99.9% fake or relabeled 15ns chips. I also have some which are blanks like your chips.
If you want to go 10ns: some modern 128k 10ns cache can be used (Cypress made some) which officially are 3.3v but have a tollerance up to 5.5v which can work but ymmv. You also need a interposer to make that work as they are not dip chips. I also have some 32k 8ns EliteMT ones which are really nice.
I have heard of those relabeling scams. It is unfortunate because it is probably very difficult to detect. Any idea how to spot/test relabeled chips? I would like to check the chips I got from AliExpress.
I had some 386 board back in the day with fake cache chips soldered in, not even socketed, so I assume the board maker was perfectly aware what they were doing (or some middle men added the chips). Those fake modules were visibly fake and had extremely "plasticky" feel. I assume they were completely empty plastics with legs because no BIOS or software would show any cache at all.
Yes, the BIOS and the cache chips had to be changed - so, looks like a collaboration.
I found a computer next to a dumpster with a fake Pentium 200 that was a relabeled Pentium 100 but the BIOS also reported it as a Pentium 200 so I guess it was also modified.
Until Windows XP, the system properties dialog did not display the CPU speed so it was fairly easy to hide the actual CPU speed from basic users who never used information and/or diagnostic programs.
Oh wow! I didn't know they did that for CPUs too!!! I wonder if I ever will come across one of those BIOSes.
I have an Asus board I bought where I suspect the BIOS was modified and fake cache chips are being used. I set the project aside several months ago to work on other projects because I couldn't figure out why all tests showed only one cache, including CACEHCHK and SpeedSys from the Phil's DOS Benchmark Pack. With this video, I'm curious if I am running in to a similar situation like what you experienced here. Unfortunately I don't have a chip tester or EPROM burner to troubleshoot.
You should be able to use a multimeter (if you have one). It just confirms if the legs on the chips connect to something internally. Otherwise, having a strange behavior in CACHECHK or SpeedSys may be an indicator, but it could be that the cache is just faulty. I think the best method would be a multimeter.
I had the exact same thought. They probably took the stock BIOS, searched for "None" and replaced it with "256K" and put the empty chips in the board.
I would upload a copy of it to the Retro Web as-is, and a copy where you search for 256K in the file, replace it with "None", test it, and upload it too.
The original BIOS is already on The Retro Web with the appropriate note. I will try my best to learn how to undo the modification.
Sadly, not unheard of. I have a pentium 90 motherboard with fake cache chips. Unfortunately they are surface mounted so I can't change them. Great video, keep up the excellent work 👍👍
Thanks! Eh, soldered fake cache chips are annoying and it's probably difficult to find real replacement chips.
Yeah, this is even one step ahead of the famous PCChips Boards with fake "write back" cache. I have two of this M919 Baords. One green PCB with the plastic fake chips and traces to a roundabout and a later version without the chips but with the right cache modul and real 256kB. There are also fake chips with marking and legs but they are hollow on the underside.
I have one of those M919 boards that needs to be repaired. The CPU was inserted in a wrong orientation and blew up the socket. Crazy to hear all those stories about fake cache chips and the extend!
I have seen some of the fake chips made of plastic, not epoxy.
You can melt them with a soldering iron.
I was really suprised, I have never seen this before.
Wow! I think these ones have an epoxy body - at least they felt like it. I did not put a soldering iron close to them yet. But maybe we will open one of them.
I have a 486 board that had fake cache chips installed and modified BIOS too. I replaced the cache chips and now I have working L2 cache, but I never updated the BIOS. It seems that the amount of cache shown and the option to switch on/off external cache has been modified, but the cache itself works correctly when the appropiate chips are installed 😅
Oh, I did not test the BIOS setting to switch off the cache. That would be interesting to test how well the BIOS hack was implemented. But I have a feeling that it might report correctly as NONE when "External Cache" is turned off in the BIOS since it probably accesses a different routine in the BIOS.
You can take the chips to a dentist. Nowadays most dentists have digital X-Ray machines. They have a good resolution and can look into the chips without any damage.
I do that pretty often, usually reverse engineering sealed obsolete modules to fix old machines.
You can't see what is exactly on a chip but you can clearly see if there is a real chip inside.
Haha, I don't know what my dentist would tell me if I show up with a bag of chips for him to put in his X-Ray machine :) I can only imagine the look on his face (before he kicks me out) :)
There's a "notes" field in TRW's ROM section. A perfectly fine place to put a note that "this BIOS reports fake 256k cache", and it can still be put there for all to gawk at the nasty shenanigans. Regardless of whether it was an evil thing to have done by the manufacturer, it is still part of history.
That is exactly right! The BIOS is already on TRW with a note similar what you mentioned.
I remember this from around when I started building my own PCs around 1993.
Without access to the Internet or much in the way of peer help, This rubbish convinced me that Cache made no difference for years.
Oh wow! That is what I wrote in an answer to someone else! EXACTLY! If you see this, you definitely will say that! Crazy - I am sorry that you were misled by this.
Your bios version is 4.50g in both cases ..What you read is known as info text . The fake bios may not have nothing new or improved, but tish infotext and date changed.
Both BIOSes are quire different. I will show that in an upcoming video. I think the 4.50g might be the AWARD main version. 1.2 and 2.01r is probably for the content of the BIOS (could be very different from board to board or even from version to version). I remember that v4.50 and v6 makes a big difference when modifying BIOS logos that appear on the screen (Energy Star Logo).
It would be interesting to scalp one of the fake chips.
I have a feeling there's nothing in them...
I remember this era, where even PSUs could have brick material inside to make it seem heavy and higher quality 😂
Haha, crazy! They still sell USB chargers with extra weight to make them feel "more premium".