Motherboard hacking for 2.5-speed increase. IBM PS/1 restoration and Sound Blaster troubles...
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- Опубликовано: 19 авг 2024
- Restoration of an IBM PS/1 486. Vintage DOS gamer ...from the local church!
Part 1 here: • You're not going to be...
Part 2: This video!
Hacked BIOS here: ps1stuff.wordpr...
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Tools I regularly use
DeoxIT D5 Contact Cleaner
Hanstar 861DW Rework Station
Pro'sKit SS-331 Desoldering Station
UNI-T UT61E Auto Ranging Multimeter
UNI-T UT890D Manual Ranging Multimeter
MESR-100 mk2 ESR meeter
PINECIL Soldering Iron
PinePowerPSU
TS-100 Soldering Iron
AMTECH NC-559-ASM Flux
MaAnt Grinding Pen
Multicore 60/40. 0.38mm and 0.5mm solder
TL866 II Plus Programmer
Tektronix 2246A 100 MHz four-channel analog scope
PCBs from PCBWay.com :)
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Music by Karl Casey @ White Bat Audio
Part 1 here: ruclips.net/video/49ZOxgc2pXI/видео.html
Part 2: This video!
New on patreon.com/Epictronics
Yes your board supports 16K cache with the hacked bios as you can see in speedsys.
The 8KB cache report is probably some hardcoded value (most likely it goes a bit like IF (cache) print "8KB" ELSE print "Disabled")
Too bad I don't have an ODPR75 to compare with. They have 8k of cache. Was there ever a DX4-100 with 8k?
@@Epictronics1 most AMD dx4 have 8kb, yes
@@Dxceor2486 Perfect, I'll see if I can find one and do a comparison
@@Epictronics1 beware though, even though this is very rare, you can sometimes get a 5x86 rebranded as a dx4-100 with 8k
... Which has 16k
It happened to me once. In this (very rare) case of putting a dx4 with "8k" of cache and you see 16k, test it in another system just in case
@@Dxceor2486 Ok, thanks
Please remember that when playing midi/adlib it works differently internally then playing a wave file. It sounds like it's sharing a interrupt or dma channel.
I think you're on to something there
A DMA channel conflict was exactly what I was thinking as well. Wave playback on the SB cards need their own DMA and IRQ while the base address is primarily used for the Adlib/OPL music playback or for addressing the MIDI/controller port. A DMA channel conflict can also cause the system to hang or act a little screwy in some cases.
@@Choralone422 Thanks, I'll make a fresh install on another system and do some more tests with this card
I was thinking the same thing. Easy test is to go into the BIOS and disable all serial and parallel ports.
By the sound of it - it is not a DMA conflict. More like an IRQ priority problem. IIRC back at that times there was such a thing as an IRQ cascading with IRQ #0 being assigned to timer, IRQ #1 to keyboard and IRQ #2 assigned to another PIC handling extra 8 IRQ channels from #8 till #15. If you had any device sitting in this 8..15 range doing intense bus transfers it would cause issues with that IRQ priority being higher than sound card IRQ channel, no matter it being 5 or 7, and as a consequence sounding like SB does sound in this video. Problems like these were most painful in early PCI era when your PCI A/B channel for the slot your PCI SB card was sitting was PNP auto-assigned to IRQs channel having lower prio compared to SCSI or IDE controller. Any burst of disk activity would result in sound artifacts like these. Thus what I'd do to troubleshoot the issue here is to disable onboard disk and video controllers if possible and try using external IDE and SVGA cards to check if it helps. Can't make any promises though as I'm writing all of this from the memories I've got aging back to 90s-00s and it was, you know, quite a long time ago.
Looks like your FSB is set to 25 instead of 33 with the DX4 100 ODP. Aside from that, looking good.
Yes, that is correct. The next step is to figure out the clock circuit. Thanks
@@CobraTheSpacePirate Thank you :) I think you are on to something here... There is no J37 on my board. However, while looking for it online, I found a very similar board that was sold with a 33MHz CPU... I'm waiting for parts right now, but there will definitely be a follow up on this project :)
@@Epictronics1 25mhz might be why your sound card isn't working properly. The ISA slot might be on 25/2=12.5mhz - which many cards could handle. 33.3/3=11.1mhz and that might be all the difference needed.
@@Epictronics1 looking forward to your follow up. Your PS/1 videos are my favorite!
Very cool! Always amazed at the quality of IBM builds. Even their cheapo PC clone is better made than most Macs to this day :)
I’m impressed by the soldering of the extra VRAM chip. I would have loved to have seen benchmarks after the intermediate upgrades (256KB of cache and DX2/50), to see how the build progressed in performance at each stage.
Thanks
I'm always impressed with your camera work and production quality. Keep it up, young man.
Thank you : )
he does have nice camera work and editing.. but his vocals and audio fullness like narrating performance needs work. At least it isn't CoreTek which I use for white noise to fall asleep too.
@@naikjoy Thanks for the feedback. Could you be more specific? I'm still learning
@@Epictronics1 uhmm Idk how to describe it. You know like if you watch an interview with Chris Williamsom and Andrew Huberman about some neurobiology and their voices have a bit more umph to them..its not like its base and low frequencies much. I mean it is but its subtle and not all in your face / ears.. but like its pleasing to listen and more into you..more forward... and yea its nice.. I think the same is with LGR vids where his background lounge soundtrack are nicely in the back and his cheerful voice which its output its probably a bit more louder talking as if he was in a bar but at 7 pm... and like.. you can hear him nice loud and clear and cheerful... very good presentation and vocals and the sound quality its nice too. I think this now comes more to comparing how other podcasts or youtubers do it and how to replicate their quality on the cheap.
@@Epictronics1 but yes another thing is.. this is why PhilsComputerLab because of how his voice and how he narates and how pleasing is to listen too and his accent isn't as great as LGR.. this is why he is only at 133k subscribers.. plus very blend sense of style old fashioned thumbnails n shit like that. I think the best dude to watch and learn from..like by watching and recreating his style..reverse engineer his style is OptimumTech videos. Now that youngster does a good job. His camera work and editing is nice.. his sense of style is nice.. he is quite a cute looking sturdy man.. BUT his voice could be better more manly with a better presence.
Man, the way you talk reminds me of Christopher Walken. It's great
I like you approach to max everything beyond its limits.
Danooct1 uses something that syncs his monitor's refresh rate to the camera. I'm not too familiar with DOS but I think it's an interrupt that sets the refresh rate of his monitor. His systems always boots into DOS with a message saying "int 10h hooked" or something like that. That could be something to look into.
I had a look at his channel but didn't see any videos about it. Hopefully someone who reads this and knows what software that is will let us know
"Even Rocky had a montage."
I was enjoying the video already but the smug Mac 128/512 got you a subscriber lol. He best be a reoccurring character from time to time lol.
Thanks :)
Love the smiley face on the LEDs @18:04. 🤣
I couldn't resist : )
The reason why the first sound card stuttered on startup sound and not on the MID file was the former is playing back a digital audio file using the DAC, and the latter uses and FM synthesis chip. DACs require much higher bandwidth from the CPU to the sound card at 44.1K transfers/second, where a MID file is relatively simple note on - note off signals which are probably much less than 20 transfers/second. If your DMA isn't working correctly between the sound card and the system then WAV sound won't work without stuttering.
Thanks, I'll do some more tests with different DMA settings
Or there is some trouble with the PCM parts of the board.
One of my Sound Blaster 2.0 had a hanging IRQ. Sometimes, on Windows, it would hang and play the same segment of the wave file like a skipping CD player. After about 15 years of bending the card, I checked the solder joints on the SMD chips and the outermost pad on one didn't have any solder on it, I could slip my fingernail under it. Guess what signal that was? Of course. The IRQ line.
haha, I guess I should check the solder joints
I did notice at 25:33 the cracking seemed to coincide with the hard drive reads, and then you had the same issues with running the game, which was accessing the CD-ROM at the same time. From memory (pardon the pun) that usually suggests a DMA issue. I would double check your DMA jumper settings, possibly try different settings, and obviously make sure your SET BLASTER environment variable matches the jumper settings. I believe DMA 0 is usually reserved for the system, so you should be able to use either 1 or 3 for low DMA, 5 should be fine for high DMA, but you could also try 7. You can have the high DMA set to the same as the low DMA, but that causes issues in some games, because it's basically doing two 8-bit transfers instead of a single 16-bit transfer, so it's probably better to have different low and high DMA. Might be worth trying different IRQs too, either 5 or 10 are usually free, 7 is usually LPT1, and I think 2 is used by something else. MIDI/Adlib doesn't use DMA, which is why canyon.mid and Planet X3 work fine.
That's very helpful, thanks. I'll give it a try
IRQ 2 is cascading to the second PIC that handled IRS 8..15. I.e. IRQ 10 signals itself through IRQ line #2 to the CPU. If you've got a choice between IRQ 5 and 10 - 10 is better as it is higher priority.
i remember all of these ... pc building were so much fun than nowdays
Totally agree :)
Vogons talk about a "single-cycle DMA bug" with the SB16, in relation to playing SB Pro sounds.
I'll check, thanks
It seems like the chip responsible for the wave output on the SoundBlaster is the problem, which is why the midi still sounds fine.
Orson Scott Card wrote the dialogue for The Dig? Cool, I love his books! Looking forward to the next video :)
It's an awesome game :) Thanks
Very nice upgrades! Looking forward to more on this PS1
Thanks : )
My uneducated guess concerning the cache is, that the benchmark "knows" that there is cache, regardless of what the BIOS says, hence it will access it. And even if the bench doesn't know about the cache, I'd wager, that it just tries to access it, where it ought to be.
I'll make a comparison ones we have 3v on that board. That will give me more CPUs to choose from for tests
THE 486DX procs were amazing, I had a DX4-100 which depending on the board you could run it in a few configs 3x33Mhz, 4x25Mhz (hence the DX4 name) or 2x50Mhz ,if you had a good board and decent VLB devices (VGA Adapter and Multi I/O card) that could run up to 50Mhz it would be the fastest config you could run and still be "in spec"
My first PC ! Glad to see it alive 😂
You were lucky then, very nice machines : )
I love these kind of videos seeing hardware pushed beyond its original limits. Good stuff! 👍 Also, I seem to remember watching some other videos that said DOOM is limited to 30fps max. If that's true you're not far off from max FPS with the 75Mhz 486. It will be interesting to see if you can hit 30 with a faster processor.
Thanks. I guess we need to find out if it can do 33MHz
Doom is capped at 35 fps.
@@gameblabla Thanks
Definitely following to see what other mods you end up doing. I've got a PS/1 2155 and done all the upgrades I could think of - max cache, memory and CPU, but was too chicken to try any of the soldering mods like the FSB crystal or VRAM.
We'll solder some more on the MOBO this week :)
Now the ZIF RAM should work on the VGA, if I am correct that VGA tests the RAM in a linear address check for the RAM and if a hole if found it simply stops and you would have such a hole before the ZIF RAM before adding this chip, so yes I believe it should work now.
There is a missing chip very close to the ZIP socket. Maybe that is causing the problem? Unfortunately, there is no documentation about the socket to be found online
Cê tá bem identificado irmão kakakakak
Hmm... do you mean that the system might require that extra soldered chip to put the ZIP ram in use? We can try that
@@Epictronics1 from what I know from having one of those VLB cards long ago now that it has the other half of a megabyte it should be able to add the last ZIF chip with 512Kb or 1024Kb, though this will hinge on the BIOS being the same
@@wskinnyodden Thanks
This board looks very similar to the board Packard Bell used in their 486 systems, except the riser card was either 3, 4, or 5 slots and went perpendicular instead of parallel.
If you can find a loose CL5428 video chip and the matching video buffer chips, you might be able to upgrade it to slightly faster graphics and 2MB of video RAM.
Sounds like a fun project. Do you know if they are pin compatible?
Not making Dig and The fate of Atlantis movies is Lucarts arts biggest lost opportunity
Those restore disks may not be totally original, otherwise it would come with IBM's PC DOS, instead of MS-DOS.
That's a possibility. Hopefully someone who reads this and have an original set will let us know
I've seen sb16s digital audio crackle with CD access when the drive is connected to the soundcard, as opposed to the IDE on the motherboard. Easy to avoid if the CD drive is standard IDE and you have a spare IDE connection. But if all are used, or you have a proprietary CD drive, you may be stuck with it. Though, the windows start sound wouldn't be affected I don't think. But worth a quick test.
I'll do a test
I'm sure that IBM thinks not locking down the original IBM PC was a mistake. The real question however, is if they had locked it down and the clone systems never arrived, would it's architecture have become the world standard ? Probably not.
And other machines would have flourished more. Looking at Amiga machines...
That is a very good question. I feel bad for IBM for having lost it all. At the same time, the clones made computers accessible to more people and that is always a good thing
@@josedias5514 Yes, I can't quite understand why Commodore lost the game having the Amiga. looking at the market today, Apple and PCs coexist quite nicely on the market. Why wasn't there room for the Amiga?
@@Epictronics1 Comodore lost out because they were comodore. Ibm didn't loose out even making the same mistakes but they're Ibm. Apple didn't lose out because of the will of Steve Jobs but comodore didn't have any aces up their sleeves. The amiga's were ahead of everyone else but couldn't shake the low value ghost. A shame it was.
@@josedias5514 yeah, It's a shame really. I grew up with a c64 and I'm still a big fan
A 26-year old virus. Nice surprise.
yeah, I went on a cleaning spree and found that nasty virus on many of my old diskettes and hard drives. I think I spent two full days getting rid of that damn thing :)
@@Epictronics1 you should put in the fastest math co-processor in this. DOOM & other programs run faster with a math co-processor.
@@andrewsadach3194 There is NO floating point math in DOOM - QUAKE was the game that pioneered use of the Floating Point Co-Processor. The reason DOOM runs better on some DX chips is because of Cache Size, Cache Policy [write-through or write back], & clock speed. Almost no Software used a Math Co-Pro except Lotus 123 & AutoCAD until QUAKE.
@@sionfiction9566 DOOM doesn't use the QUAKE engine. It was made using a variant of AutoCAD. All 3D DOS games used some form of AutoCAD back then, and combined them with BASIC programming language. That's what the DOOM game engine was compromised of.
@@sionfiction9566 before Blender, Unreal, and Unity... Everyone used a AutoCAD variant for 3D games.
I have a PAS16 sound card with similar issue
Midi work
8Bits PCM work
16Bits PCM work for a few seconds.
Playing a game with 16 bits sound enabled will get the music and sound effect to work initially then the effects will stop playing and the music will continue.
Sounds like a bad chip to me. I'll see if I can figure it out
5:10 - "You'll need nine of these buggers"
Correction, you need eight of those buggers, plus one TAG SRAM chip. If you put nine of normal SRAM into a motherboard, the cache won't work properly, and may cause the system to become unstable from not having the TAG chip. TAG SRAM is special SRAM that stores a lookup table of cache entries and has some additional logic to tell the system where those cache entries are.
It's obvious on that board where the TAG goes, because it's a socket off all to itself, away from the other SRAM sockets. The TAG socket is also sometimes smaller, because the TAG SRAM is a smaller capacity memory chip, unless you have a large amount of cache installed.
Another gotcha is that you need to use the correct TAG SRAM size. If you use a chip with not enough memory, it won't be able to hold all of the cache entries, and may cause erratic system behavior. I think for 64k and 128k of cache, you need a 16kx8 chip. For 256k, you need a 32kx8 chip.
Ok, I think the manual just said to put an extra chip in that socket. I'll double check, thanks
@@Epictronics1 While I've never seen it myself, there may be some motherboard designs that have the TAG circuitry on the motherboard, rather than requiring a special TAG SRAM chip, and it just uses a normal SRAM to store the cache entry table.
As you said, you'll need to consult the motherboard manual. Hopefully it's clearly stated whether it has on-board TAG circuitry or not.
But it's more common than not that the motherboard needs the special TAG chip in the dedicated TAG socket, and the correct sized chip.
@@GGigabiteM I'll check, thanks
@@GGigabiteM To my knowledge, I've never run across a motherboard that requires anything special in the tag socket. It's just another SRAM chip. It may not be the same capacity, like you said, depending on the amount of cache installed. But, I've always treated it as interchangeable when they all call for 32K (e.g.) and that's never been a problem. It never even occurred to me that it would be any different.
@@nickwallette6201 TAG SRAM is NOT another SRAM chip, it has comparator circuitry for hitting cache entries.
YT shadowbans posts with links in them, so you'll have to look these parts up yourself. Here are just a few TAG SRAM chips from different manufacturers.
SGS-Thompson MK48S80-15
Integrated Device Technology IDT 7174S
Logic Devices L7C173TC-15
You can have all of the cache you want, but it's not going to work properly without a TAG chip, because the TAG chip tells the system when there's a cache hit. If no TAG is present, the cache will fill up, but it will either never be used, or have erratic behavior from OE2 toggling at inappropriate times.
On TAG SRAMs, pin 1 and 26 are different from normal SRAMs. 1 is RESET/CLEAR (clearing cache entries.) Pin 26 is MATCH, which is used to determine when a cache hit is detected. On normal SRAMs, pin 1 is normally N/C (not connected) and pin 26 is OE2 (output enable 2.)
I have a 386sx25 laptop with 4 megs of ram and it runs doom fine.
The Dig is such a great game.
Totally agree
You can always check and see if somebody's made a coprocessor, or GPU out of the RP 2040... That would probably speed it up a whole lot if they did
the FSB is only running at 25MHz.... you can see in speedsys its clocked at 75MHz (25x3) the 3 jumpers one of them should set it to 33MHz or you need another Mod. lots more speed left in it when you go to a 33MHz FSB
Yes, that is my next goal, to figure out how the clock chip works. Maybe, it's hackable too
@@Epictronics1 I'm thinking there's a 25MHz oscillator on the board that needs to be swapped out with a 33.333333Mhz version. There may also be a divider circuit to keep the ISA bus frequency in spec, so you may need to find a 1/3 divider and replace it with a 1/4 divider, may be a jumper, IDK.
My memory of this stuff is all a little... not good, but here's some things I THINK I remember that might help...
486 bus speeds were 20, 25 & 33Mhz [There may have been a few 40 MHz Motherboards later in the 486's life]. As I recall Clock was typically set either by Jumper or in the Bios - you shouldn't need to fiddle with crystals or anything. The DX2/4 & SX2/4s were the first 8x86 CPUs with a disconnect between Internal & External Clock speeds. DX2s were clocked doubled & DX4s were actually clock TRIPLED - So a DX4 100 runs internally at 99Mhz while the Bus runs at 33. I could be wrong but I do seem to remember also that changing the Bus Speed also changes the ISA slot Clock speeds & anything plugged into them. So if your SoundBlaster 16 was an early model it might not like what is essentially an overclock.
Interesting project Epictronics, brings back memories from when I used to work on this kind of stuff.
@@sionfiction9566 Thanks. I hope they are good memories :) Yes, we might get into some compatibility issues when we start clocking the board
Hi, I tried installing the OD Pentium 83MHz on my PS/1 2168 placing the jumpers as described on the manual but the PS/1 will not POST. I guess I need BIOS chip FRU 76H6938. Anyone know if that exists somewhere to download a copy?
Good video! At 5:25 is the cap next to the slot (that's semi-bent over) ok? it looks like it might have a broken/barely attached leg. I can't remember if you recapped stuff in the first episode so it might be brand new and fine!
Thanks :) The caps looked a bit funny on this board. I better check
It’s a beautiful machine!
It sure is : )
Windows settings are set IN windows not DOS. You need to set the address within windows for changes after the initial installation.
Hence the system.ini file, which is a windows config file. I was thinking the same thing.
It got lost in the edit. I did the settings in Win unfortunately
Yep. Certain (most?) versions of the DOS configuration utility would write to system dot ini as well, if it had been told Windows was installed. But it's possible that some don't. I don't remember having to edit the Windows configs by hand much for Sound Blasters. Certainly for other cards, though. I think the Drivers control panel applet had a settings page for the Wave device driver that exposed those settings in the GUI.
A sound card is 2 separate cards in 1 and in this case 3 of them. The reason why canyon mid and planet express 3 both sound good is because they are midi. The windows startup sound is wav. That's different hardware. So the midi part of the card is good, but the wave part of the card is bad. That's what's going on. I would even say PX3 doesn't even have sound. When I think of sound I think of wave not midi.
ok, thanks, I suspected something like that. This will narrow it down when I do the troubleshooting
@@Epictronics1 yeah it's like 220 is one piece of hardware and 330 is another piece of hardware both on the same board. (I think those numbers are right. lol)
@@Epictronics1 In fact the early soundblasters (probably this one) has a yahama chip (I think it's yamaha) that is the same chip on an adlib card and a separate chip that's for wave. I believe later on they combined them, but inside the silicon it would be 2 completely different sections of the silicon.
@@awilliams1701 That is correct. This SB has a real Yamaha OPL-3 (edit)
@@Epictronics1 Pardon? Adlib is OPL2. SB16 is OPL3, which is software backwards compatible but not electrically compatible.
One potential trouble is that the Soundblaster chips still do address decoding for the OPL, making them not super super separate; but also given Adlib mode works fine, that is something we can disregard for the time being. Also OPL subsystem doesn't need any IRQ or DMA, it's purly IOP, which makes it much simpler.
maybe faulty capacitors on the sound card?
That PlayStation one looks really odd It must be a dev unit
IIRC the original Doom engine caps the framerate at 35 FPS.
We better get that bus up to speed then : ) Thanks
awesome video!
Thank you : )
@Epictronics1 can you link the Tom BIOS? I have an older 2133 486SX 20Mhz with a VLSI Bobcat chipset and onboard ET4000 video chipset. I'm wondering if this BIOS is going to help out supporting an AMD 5x86 overdrive. Also, to make it faster you should check for a CF card adapter or SD card adapter instead of that old hard drive.
It's not uploaded anywhere. Any suggestions for a suitable place to upload? Does your board support the 3.45v required for the 5x86? If not, you may want to watch one of the upcoming videos :)
I did notice that the printer port in BIOS was set to a rather odd 3BC rather than the usual 378 - might this be having some impact on the address ranges that are used for the sound card?
I'll check, thanks
It shouldn't. The digital I/O is all down at 0x220, with the end of that range supporting the CD-ROM interface. The OPL chip can be accessed in the 220 range, or at 0x388. Neither will conflict with the parallel port at 0x378 or 0x3bc. IIRC, 0x3bc was the original address for LPT1, used back in the PC / XT days. 0x378 became normal later.
Man, that intro for The Dig NEVER gets old.
I'm curious: I understand your wish to keep the bodge visible, but wouldn't a long wire like that, on a high frequency part like the CPU, work as an antenna and be susceptible to interference?
It's possible. I have another system that I bodged about a year ago. I haven't seen any issues yet. If it starts misbehaving, I know what to check, thanks
I see on vogons a bios version supering 528MB limit, unfortunately I can't link here.
I'll see if I can find it, thanks
I actually have a ps/1 2168 tower very much like the one featured in this video, so definitely relevant to my interests. Is there a writeup anywhere on the upgrades featured in this and the previous video?
I found the "disable onboard CPU Hack" on Vogons years ago. Otherwise, I don't think there is one.
15:00 the best way to damage chip and scratch PCB under the socket damaging the fine traces. Bravo. Because chip pullers are made for pssies, right? Right?
I damaged quite a few chips and traces with chip pullers before I finally found this wonderful tool : )
@@Epictronics1 I have quite an opposite experience. When you leverage that "tool" against that square chip it's just a matter of time when its 30+ year old brittle plastic will crack. Well, it's your life but this kind of "repair" videos give chills to many retro enthusiasts for sure.
@@nneeerrrd I thought you were joking? I use to use chip pullers, but they damaged pins and traces. Then I found this tool and I haven't damaged a chip since then?
Where does one obtain Tom's hacked BIOS? I have a similar PS/1 board but haven't been able to use an OverDrive because of the BIOS freaking out about the cache.
It's not available online. I have sent an email to the IBM PS/1 Resource Page to see if they want to host it. If they do, I'll post a link in the description of this video.
I would also like to get a copy of that BIOS for my ps/1
@@natasegde I'll put a link in the description ones it's available somewhere for download.
you might try disabling the com and parallel ports in bios, been long time but I recall one of them uses irq 5 and if its trying to share the irq with another device it can result in messed up audio.
Thanks, that's an easy test. I'll give it a try
I was thinking the same thing, and the parallel port is normally the culprit. For extra safety I would also disable both serial ports. I've had a sound card share a parallel port before without any issues except I couldn't print and play music at the same time. I'm not certain but the PS/2 might be sending bus data to the parallel port even though the port isn't selected. Many early machines did this because actually disabling the parallel port required extra chips. Setting the busy signal on a parallel port would tell the printer to ignore anything you "see" being sent.
@@therealjammit I'll give it a try, thanks
i had an ibm pc jr
Love the content. This may be a daft question, but is there an easy way to fix the worst of the monitor flicker in your video editing package? Like the duplicate, 50% opacity, two frame offset trick in Premier Pro? Given the static camera, that sort of technique might be an easy way to make it significantly easier to watch.
I am not aware of any tricks to solve this yet. I'll do some more reading and I'll figure it out. The ideal solution would be to adjust the refresh rate on the CRT with software to match a camera setting. Thanks
@@Epictronics1 except you can't adjust the refresh rate in the BIOS screen. That's most likely hardcoded to be 640x400 @ 70Hz. Good luck getting a camera to sync up with that.
Easy solution. Not period correct, but cheap and easy. Use an LCD. Preferably with a period-correct aspect ratio of 4:3 or 5:4. Those should be cheap and somewhat easy to source on the used market still. I just saw one (17" SXGA) going for $5. That will eliminate any camera-based flicker.
@@SeeJayPlayGames I've got a couple of those but I try to keep things period correct as much as possible. I'd be happy if I could just get rid of the flickering in DOS and Windows
@@Epictronics1 unless you can adjust your camera's shutter speed to not flicker at 70Hz... nope. LCD = easiest. Some modes are 60Hz and wouldn't flicker, but a lot of them are 70. Mostly the 200/400 line modes such as those used by the BIOS and command prompt. Windows, you can get running at 60Hz most of the time. Although there are some modes that are like 56Hz or 72Hz or even 87Hz interlaced. This is really only a big problem with IBM compatbles and Macs, not earlier home computers, as most of those could be connected to a television.
@@SeeJayPlayGames Yes, I have noticed that my older machines don't produce much flicker. There are cameras that can be set to odd settings. I will probably get one of those when it's time to upgrade
Nice
I really want to find these BIOS chips, or a way to flash my current IBM 2133A BIOS with this hacked one. I've been planning this for months and its almost time to put in that DX4-100!!
awesome, good luck
@@Epictronics1 any chance you can direct me on where to buy one of these flashed ROMs or how to flash my current one?
@@rjwelchiiiable Sure. All you need is a programmer. I use a TL866 but there are others. The file to the program is linked in one of the PS/1 videos.
@@Epictronics1 Thanks for the info. That may be out of my scope for now. It's beyond what I know how to do currently. Any chance you have any for sale?
@@rjwelchiiiable Unfortunately no. You could check with your local vintage computer club. Someone there might have a programmer.
Can you change the clock speed multiplier resistors to make faster?
That's what I'm going to try next :)
Hi Epictronics, did you programme the hacked BIOS ROM for your IBM 2168 using a TL866 II programmer? I have a Pentium Overdrive on order (PODP5V83) I am rather hoping it just works, otherwise I might need to tool up to learn how to programme EPROM for the first time! My 2168 looks similar to yours except the sockets are different: the original 486DX2-66 is fitted into a blue Overdrive Ready socket (the location of your original processor is not populated on my board), it is PS/1 2168 '493'. The bios is 52G2974 12/05/93. Thanks as always for the great content
Thanks! Yes, I used a TL866 plus. Good luck with the project
Thanks, D48 on order so going to take a backup of the original rom and take grub there.
@@Epictronics1 Thanks again for your help with the name of your programmer. I took a dump of my 2168's BIOS ROM (12/05/93 /
52G2974), but alas so far not been able to get PODP5V83 to post even with adjustment to j23-j25. I think my model just must be too old compared to the release date of the overdrive
I tied this, I also have the blue overdrive socket on my 2168 and installed the 83MHz pentium OD. Yes, it will not POST. We need BIOS FRU 76H6938.
Have you checked the size of the Chip for the Graphics Chip?
Maybe that was the reason it didn't work?
I'll double check
Great video
Thank you : )
@@Epictronics1 you are welcome
I laugh every time you say IBM-compatible IBM. 🤣
Things got really weird back then : ) Silly mistakes were made
@@Epictronics1 Oh I know, I remember when IBM lost billions due to losing their monopoly in the PC market. Once the BIOS was hacked/copied/reverse engineered (take you pick), the gates were opened for 'IBM-compatibles'.
BTW, hi Mac. 😁
@@JenniferinIllinois Bad-mannered Mac Harvard says, Hi : )
very nice upgrades! Can the video RAM be expanded even more? My first video card had a similar issue, I could only go up to 800x600 16 colours (and the monitor could only do 640x480, awful). So sad about that sound card! I hope you can fix it (which reminds me I have two I am trying to fix!)
Thanks Tony. I was hoping to find out with this project, but I don't seem to have the correct ZIP chips to do the test. Unfortunately, I can't find any documentation. Also, there is a chip missing near the ZIP. Maybe that's the problem?
Max video memory I ever found on a ISA video card was 1M but on a VLB 2M were supported (mostly upgradable or on high end cards). 2M+ were on PCI bus (2M or 4M on high end cards). So, my tought is that the soldered chips are meant to be 512k (low end) + 512k (low end factory upgrade) + 1M socketed memory chip (optional upgrade for high end). Maybe Epictronics check a chip in that socket now, after soldering that memory chip? (for missing pinout, just identify Vcc and ground pins to find the correct orientation)
@@sebastian19745 I'll try it out, thanks
@@Epictronics1 Note that socketed ZIP RAM chip only takes 40-pin 80ns sticks, and that seems to be what you used. It has a datasheet that gives a -1 to 7 volt CC and in/out rating. If either stick works in anything else, I say maybe test the socket for voltage, if the test Sebas suggested fails.
Doom wouldn't run with 4mb? I only had 4mb of ram until 1995 and I ran Doom on a 386DX40, 486DX2/66, and a 486DX4/100 ll with 4mb before I finally upgraded to 8mb in late 1995.
I got a memory error when I tried to start Doom with 4MB. I didn't have time to check the details.
@Mr Guru I had 1.9. While I agree there are different versions and ems and xms memory was a huge struggle during the time it's possible to run on 4. I can also appreciate that he didn't want to fool with it and just and just more ram. At $50 a mb for ram in 1993 it wasn't as simple at the time and you made it work when you either run what you brung or didn't play.
| Awesome ! | :3
Thanks :)
Why have you removed the IBM PS/1 2133 videos :(
I'll make some new :)
@@Epictronics1 Thanks, I got one recently and I was going to use your videos as reference to upgrade it. :)
@@KhalidYousif87 Ok, you can use the 2168 videos. They have the same MOBO :) Have fun!
@@Epictronics1 thanks! :)
I was wondering the same...the ps/1 video playlist was my favorite.
27:19 George W. Bush ?
she's a beauty
I would be willing to GIFT you several 386 and 486 boards, cpus, bucket of ram, cards, anything (hell, even a voodoo, 3D-BLASTER S3, soundblasters, whatever).. If you'd be willing to fix my (legendary) FIC 486-VIP-IO.. It was working perfectly until I connected an IDE cable, heard a small pop, and she died.
I've probed around, replaced two resistor packs that were obviously bad, and the board won't switch down to 3.3v from 5v when the VOLDET pin is tied to ground (it clearly has a voltage regulator onboard, 3pin and a 5pin jobbie)- there's a bunch of info available on TheRetroWeb for the board (I have the original IO, not the IO2)
Despite being stuck at 5v, it won't post any CPUs, regardless of voltage, jumper settings, cache present or not, barebones, nothing works.. And my post-card just hangs at C0.. IF it indicates anything at all.
Thanks for the offer. That project is too big for me. Have you tried to post a thread on the EEV blog forum?
@@Epictronics1 repairing just the motherboard I mentioned is too big? Okay, thank you for taking the time to reply
Needs a 5x86 133 cpu 🤣
How about a 5x86-100?
@Epictronics1 also good2go
@@Phil-D83 We might try it soon :)