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A Mac Classic with 4mb of RAM without using the RAM expansion card
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- Опубликовано: 8 мар 2024
- After the recent Mac repair-a-thon, I had a Mac Classic motherboard with a missing 74LS174. I thought about just replacing that IC but realized I could actually do a simple mod to the motherboard to give it 4mb of onboard RAM instead of just 1! (And I wouldn't need to replace the 74LS174, so it would actually save me money.
-- Info
How to modify the Mac Classic for 4mb onboard as seen on Adrian's Digital Basement
** Remove two chips:
Remove UL1 CAS PAL (no longer needed!)
Remove UH6 74LS174 (no longer needed!)
** Modify system to think it has 4MB on the motherboard:
Pin 13 of UI4 BBU:
Remove R42 470ohm (under motherboard - this pulls pin to ground)
Pull up PIN 13 via 10K to 5V
(I did this by running a jumper between the left side of R42 and R41)
Pin 17 of UI4 BBU:
Should be pulled up to 5v already (verify but mine was already at 5v)
** Remove old 44256 RAM chips (8 of them, UK1-UK8)
** Install 4400 RAM chips (4x1mbit - I took these off a 4mb 72pin SIMM)
** Make connections to connect CAS lines from UI4 BBE to RAM:
Connect UL1 PIN 7 CAS0H to UL1 PIN 24 (CAS0H to UK1/3 DB8-14)
Connect UL1 PIN 6 CAS0L to UL1 PIN 25 (CAS0L to UK5/7 DB0-7)
Connect UI4 PIN 16 CAS1L to UL1 PIN 27 via 22ohm (CAS1L to UK6/7 DB0-7)
Connect UI4 PIN 19 CAS1H to UL1 PIN 26 via 22ohm (CAS1H to UK2/4 DB8-14)
(22ohm is just to make sure shorted DRAM doesn't kill the UI4 BBU)
Remove (optionally) and jumper over R43 and R56 (22ohm resistors) as these are in series with R3 and R19. This gives the CAS lines just 22 ohms (versus 44 ohms)
This replicates the Mac SE design exactly, in fact the Mac Classic is really a Mac SE... The UI4 BBU chip is the same one on the Mac SE, even though the part# is different, it seems to work in an identical way.
-- Links
Mini Mac Repair-a-thon:
Part 1: • Three unknown Macs: Le...
Part 2: • Not so fast! I hit som...
Part 3: • The troublesome Mac Cl...
Recapping the Mac Classic II Motherboard
• Let's recap a Macintos...
Previous Mac Repair-a-thon from 2020:
Part 1: • Mac Repairathon Part 1...
Part 2: • Mac Repairathon Part 2...
Part 3: • Mac Repairathon Part 3...
Part 4: • Mac Repairathon Part 4...
Part 4.5: • Rejuvenating a Macinto...
Part 5: • Mac Repairathon Part 5...
Part 6: • Mac Repairathon Part 6...
Adrian's Digital Basement Merch store:
my-store-c82bd2-2.creator-spr...
Adrian's Digital Basement ][ (Second Channel)
/ @adriansdigitalbasement2
Support the channel on Patreon:
/ adriansdigitalbasement
-- Tools
Deoxit D5:
amzn.to/2VvOKy1
store.caig.com/s.nl/it.A/id.16...
O-Ring Pick Set: (I use these to lift chips off boards)
amzn.to/3a9x54J
Elenco Electronics LP-560 Logic Probe:
amzn.to/2VrT5lW
Hakko FR301 Desoldering Iron:
amzn.to/2ye6xC0
Rigol DS1054Z Four Channel Oscilloscope:
www.rigolna.com/products/digi...
Head Worn Magnifying Goggles / Dual Lens Flip-In Head Magnifier:
amzn.to/3adRbuy
TL866II Plus Chip Tester and EPROM programmer: (The MiniPro)
amzn.to/2wG4tlP
www.aliexpress.com/item/33000...
TS100 Soldering Iron:
amzn.to/2K36dJ5
www.ebay.com/itm/TS100-65W-MI...
EEVBlog 121GW Multimeter:
www.eevblog.com/product/121gw/
DSLogic Basic Logic Analyzer:
amzn.to/2RDSDQw
www.ebay.com/itm/USB-Logic-DS...
Magnetic Screw Holder:
amzn.to/3b8LOhG
www.harborfreight.com/4-inch-...
Universal ZIP sockets: (clones, used on my ZIF-64 test machine)
www.ebay.com/itm/14-16-18-20-...
RetroTink 2X Upconverter: (to hook up something like a C64 to HDMI)
www.retrotink.com/
Plato (Clone) Side Cutters: (order five)
www.ebay.com/itm/1-2-5-10PCS-...
Heat Sinks:
www.aliexpress.com/item/32537...
Little squeezy bottles: (available elsewhere too)
amzn.to/3b8LOOI
--- Links
My GitHub repository:
github.com/misterblack1?tab=r...
Commodore Computer Club / Vancouver, WA - Portland, OR - PDX Commodore Users Group
www.commodorecomputerclub.com/
--- Instructional videos
My video on damage-free chip removal:
• How to remove chips wi...
--- Music
Intro music and other tracks by:
Nathan Divino
@itsnathandivino
Make sure you document and publish this, I think people will find this useful. It would be awesome if this was the world's first 4MB hack of this machine! Did I mention you deserve much more views and subs?
Thanks! Hopefully one of the folks in the Mac community copy the instructions (From the description and share it around for others to try.)
@@adriansdigitalbasementlove your videos up there with the 8 bit Guy
@@adriansdigitalbasementissue is the schematics diging was genius for no trust they is like these fake parts on ali they worth the risk if you know they are no trusty
video descriptions are not searchable since Google made changes to their search algorithms. Less perfect results means you see more ads.
Amazing bit of reverse engineering/hardware hacking, Adrian! You are elite! 🎉
@6:55 nice voice change "motherboard" :P
Mr Roboto for a sec
Maybe he's going through puberty again and his voice cracked, haha.
He's really an android, and that was his real voice. 😀
Proof we are living in the matrix
OMG i got so scared there for a second too I had to doublecheck. Scary robot voice 😢
What you didn't explain is that while adding one address line increases the amount of addressed memory by 2, dynamic rams use each address line TWICE, once during the RAS clock interval, and a second time during the CAS interval. Each DRAM ram address line is muxed between TWO CPU address lines, so the memory address is FOUR times as much when you add a single DRAM address line.
Thankyou.
My brain crashed when Adrian said increased by 4.
Thankyou for explaining, I did not know this.
Definitely the sort of nerd project that I absolutely love to watch!!
Good thing you said nerd instead of geek.
Absolutely agree and it's the reason I love this channel 😀
I've done electrical repair work before but it's been a while since I've done anything like this myself.
The CAS pins are pin 17 on the chips if you don't skip the missing pins. Guessing whoever made those schematics never saw the datasheet of those memory chips, so they just didn't know to count the missing pins.
Anyway, this is a super clever hack! It's possible someone could've worked out how to do this back in the day, but it would've required them to realise that the SE and the Classic use the same chip, despite the different part numbers, and have access to the schematics (or reverse engineer that part themselves), so it's pretty unlikely anyone would've figured this out. Also it still would've been cheaper to do the standard upgrade, since those higher density memory chips would have been much more expensive than the standard ones that the Classic used.
But still, great job figuring this out! Hopefully it might help bring back a few machines that have a faulty PAL or LS174 chip.
Adrian, you are such a nerd. I love it! Please do not loose it. Been watching your channel since the beginning and I love how much you have matured with your videos. Thank you do much!
He's learned a ton along the way. And learned to apply his knowledge to new, more advanced projects. It's been fun to watch.
Such an awesome mod for a Mac Classic, especially for those boards that may have been almost relegated to worthless because the PAL was broken. Whereas the LS logic chips are pretty easy to replace even today, those discreet logic chips aren't, because as you said the programmed logic isn't fully known for these custom ICs. Using this mod, none of that matters which is so cool!
What a pleasure to see you so happy when it freaking WORKS !
Even when you hit a setback, you're able to laugh and carry on. Very nice.
Okay just finished your video and I'm currently taking apart my Mac can't wait to see if I can get it to work. The main reason I want this is for the form factor. I have my Mac in a custom 3D printed case and need 4mb and couldn't work out how I was going to get it all to fit without making the enclosure much larger than where I want it to fit. Thank you so much for all your amazing videos.
I'm soo loving the devious ingenutiy, articulately explained in the intro. There's a nostalgic aspect too for this 60 year old, as in my 20's I did a similar mod to upgrade my 1MB ARM1 Acorn Archimedes to 4MB by piggy-backing DIL chips.
I love the “really small pizza box” idea you outlined at the end, the first time I saw these motherboards I was struck by how similar they are to say a ZX Spectrum. Tiny board, a CPU, a highly integrated I/O chip, sound, and memory.
I had started building a Mac SE motherboard based rack mount system a few years back. I was planning on getting a drive set up that would just boot up and act as a local talk file server. I never finished the project, but it would fit as a pizza box ;)
f2 = Address error - f3 = Illegal Instruction - fA = Line 1111 and wow E isnt even on the list lol. This one was awesome Adrian. i was as excited as you to see the final result.
Congratulations! That's quite an accomplishment. Any RAM upgrade is good, but a default RAM upgrade like this is beyond great!
I don’t think I’ve seen anyone else attempt this! This is next level! Loved this mod. Awesome work Adrian! Superb video!
Congratulations Adrian, I got excited too when you did on the video. Call it strange, but it was exciting to watch. Kia ora from New Zealand :)
Adrian, I love your enthusiasm. I get excited to the same degree when I get a breakthrough, either he or sw. Keep up the great work!
I'm genuinely happy this worked out, and I'm glad I got to share in your accomplishment. Great job, Thank you!
These videos MAKE MY DAYS/NIGHTS! Ultimate ASMR, AND educational!
One of your best videos Adrian. Really enjoyed the hardware hack!
I am glad you mentioned how you soldered them in! I could not figure how how you could get an iron in there.
great video as always
Was not ready for 15:40 and it make me laugh out loud. I enjoy seeing you make these new mods and having fun playing with these parts. It's a good addition to your other good work.
Great Work Adrian! 👍🙂 So cool to see you work your way through problems!!
I friggin love this channel. I've already seen a video on this scandal on another channel, but I had to see John's take. Keep up the good work!
That was actually a very clean mod to run 4MB onboard. It's doubly nice that it's 100% reversible as well.
More infectious enthusiasm and anticipation. It's a great way to spend a Sunday morning in Melbourne. Excellent. 👍
This is awesome, Adrian. Very cool modification! B.t.w. You are the guy, who catch me into the nets of old hardware. And the things you do always inspire me to try interesting things myself. You are the person who "gave" me a soldering iron in hands(i have no ANY experience before last year) and I saved a few boards already and now have working 286, 486 and Pentium machines(486 and s7 are HP Vectras, and it's because of you too! You showed me this cute pizza boxes in your old video) You have no idea how much you did and still doing to people like me. :3
I like this video. I hope you focus more on this type of content as it's your main strength.
Highly unlikely that I would ever do this, having never owned anything Apple. The Apple, ][, Classic etc. where not that popular here in the UK. But this is so cool, and I just love the fact that you decided to give it a go!
That's absolutely amazing achievement! Your knowledge about computers would be very useful in console hacking scene and the repairability of those machines where no schematics coming out for obvious reason of security. And the fact that you are saying you like so much doing mods, makes smile on my face that you may add help one day to the community out there giving those wonderful machines more functionality, more repairability and make the retro community preserving their consoles. I would definetely like to see you in video like XBOX OG repair and mods, as long as XBOX 360, and PLAYSTATION mods as well.
Go on with more challenging things like this! Keep up the good work!👍
Great job you did Adrian! I love your videos and content. Greetings from Steven from the Netherlands
Thank you for documenting all this!! I finally got the courage to to some surface mount soldering and recapped a Macintosh Classic II that was non functional a few days ago and it's been a really great computer so far! It's really only thanks to you and a few others who show the nitty gritty of doing real repair like this that I was able to look at it and go "huh maybe I *can* actually do that...".
Wow its amazing how your mind works. It was a great video because it is obvious to everyone that you love what you do. Cheers and happy hardware hacking Adrian!
What an awesome hack! And the kudos you deserve for reasoning out the similarities between the two motherboards and engineering said hack are beyond the limit. The only complaint I had with this video is that you didn't show more of the solder work. I love your re-cap videos and love seeing you actually do the work on the computers. I imagine its boring for some, but I love it!
That is so cool mate! Mistakes in schematics are the worst (hello IBM 5150 reset line) but excellent work tracing and understanding the system rather than just blindly trusting and giving up. Excellent reverse engineering and hackery!
I am not a huge fan of Macintosh stuff, but this was an awesome mod! Very fun video.
I have watched a few of your videos and they helped me tackle some repairs. I was able to replace 2 failed ram chips on an apple 2e and it works great now even installed ic sockets. Then I was able to repair a multi meter that fell off a ladder and hasn’t worked since. Was a broken solder joint pad and trace on the surface mounted “clock crystal” I think. Now will be used for a bench meter since I don’t trust the repair for day to day work. Thanks for your thorough explanation of the repair processes. Much appreciated.
Quite a journey you took us on! Love the nerdy-ness of it all ^^
Excellent Adrian WOW, it just blows my mind that this could be done. Great video!!!!!!
Very well done, and a fun video to watch! Congrats! :D
Probably one of your best videos so far!
Definitely hardware hacking is cool AF.
Hope you find more fun hacks for us in the future.
Very nice, as always. Good spot on those mislabeled traces!
brother Adrian, you are a freakin genius for figuring this out mate. Seriously dude, you should wear a golden mac propeller hat! i have a mac classic logic board that i butchered when was learning hot air soldering. i pulled the 74LS104 too early and with it half its pads :/ You have now given me a pathway to fix the card and make it better like the six million dollar man! bravo brother, 2clickSando from Australia. Absolutely love your passion, enthousiam and achievements in vintage tech.
yes, very fun! keep up the great work adrian! want to see more of your crazy schemes!
Congrats Adrian. What an excellent experience.
I will definitely use this on some of my reloaded giving the customer the option. Appreciate your amazing work.
VERY nice project, I really enjoyed the whole process! Thank you!
That's a really cool mod. Glad you got it to work!
Your enthusiasm is infectious. 😄
Awesome hack, Adrian! I love to see your reaction when it Freaking Works!! And your voice change at @37:49 too.
Super cool Adrian, love seeing you hacking things like this, great stuff, heres to the next hack! 😄
Woohoo! Awesome result and great video. 🙂
Amazing hardware hack, Adrian! Congratulations!
Nice work, Adrian! Somehow it almost feels as cathartic to remove parts as it does code 😁
love it adrian! well done mate. i was watching you with those schematics and was like hmmm i wonder how legit they are. so they are mainly good minus a few things.
Hi Adrian, just wanted to thank you for videos like this, I recently got a Mac Classic which had a leaked battery and caps and was able to get it working again! Largely thanks to your videos 😁
adrian i love your videos. you have inspired me to create my own. im not the best content creator i have a few health issues in the way but im not going to let that stop me carrying on. keep the videos coming.
This is most impressive! Nice to follow your thought process through to the implementation and have it freakin‘ work at the end! I like the idea of using this mod to relocate the board into a slim box with an external display. 👍🏻
Phenomenal performance! It brought back memories of some people piggybacking Ram chips and wiring up additional address lines in an Atari 800XL to get it to the 130XE RAM count. Old times. Btw, I took especially the C programming classes in my tech Uni, because they had a room full of Macintosh Classics in 1995. It was one of very few ways to spend time with those machines in my country at that period.
At last! Love hadware hack videos. Thx so much for this!
I bought a 4 mb upgrade kit for my Atari ST back in the day, I had to solder 4 bodges to the legs of the square MCU and pull out a socketed chip and plug in a small daughter board then plug that chip back into it, it might have been the CPU. It was cool when it worked, 4MB instead of 512. But slowly the hard drive and floppy disks started malfunctioning, getting worse and worse the older it got. If I would have kept it I bet just by watching Adrian's videos I could buy a scope and figure it out, but I sold it for parts and bought my first PC. So ended my days of assembly programming on the 68000. Oh well. I have been messing around with Steem and got a c compiler working that I think I can do ASM subroutines. I want to try to recreate my sprite software library that I cooked up on my Atari before it faded into the sunset.
So my friend had a 520 ST he upgraded to 4mb back in the day..... inside was this horrible mess of wires, a daughterboard with more RAM and it was so confusing. It no longer works so he had to remove the RAM expansion and it was impossible to figure out how to reinstall it! Seems there are more modern ones available not but it's still a pretty frustrating experience on the STs. :-)
Totally incredible! Congratulations!
Awesome, I just got my hands on a working SE and another non-working classic. i havent had a chance to tear into the classic yet but i can wait to check it out and see if i can repair it as well.
Wow. Adrian. Just wow. Good job!
Amazing job, Adrian! endorphins were almost dripping off your face :-) I know the feeling when "It f...ng works!" Congratulations!
Bloody amazing work! What a legendary hack.
Excellent hack Adrian!!! Cheers from Italy
Really cool! FYI, the PWM line in the SE and below is for the older floppy drives, they need a PWM signal.
Now that's impressive. This is something I'd happily offer to someone who needs it. May even try it on my own classic for fun.
Big props for such an interesting hardware hack!
You, sir, are a wizard. Nicely done!
@AdriansDigitalBasement
Well done! I've done a mod like this before, but for something completely different. Very cool indeed!
that is freakin' cool
You are awesome. I love it when a plan comes together.
Love this kind of hackery! Well done!
Awesome! I love how you created a whole project and video to avoid having to deal with digi-key to buy that replacement 74 series logic chip 🤣
Superb work Adrian
Really enjoying these hardware hacking videos.
Wonderful to share your excitement when it "just freakin works" !
Nice job Adrian. Excellent hack.
Adrian my man... you are too smart. Great video.
Those series 22 Ohm resistors are for dampening out reflections on those traces. High speed edges imply quite high signal components that dont like unterminated transmission lines like normal PCB traces.
Back in the 90’s I was “the guy” where I worked that everybody came to to change high density chips on complex circuit boards. With just a Princess heat gun I would remove the bad chip, clean off all the solder with braid, add liquid solder paste to the pads and install the new chip with the heat gun. I was nearly 100% successful! So getting your memory chips on and off you should use solder paste! I use to buy unpopulated simm boards, pull memory off discarded circuit boards., install them on the simm boards and sell them!
I usually despise retro, You're changing my opinion. Your work is becoming legendary.
Loved this hardware hacking video. Great work.
When I was a kid, my school basically gave away their fleet of (mostly) Mac Classic and Classic II systems. There were even some LC-II's in the mix. They decided to go full in on boring cheap Wintel systems instead. As a result, my friends and I were showered in a few of these Macs! I ended up with two Mac Classics.
I didn't have a lot of knowledge on how to actually use them, and I had no idea they had a built in boot ROM. I mucked about with them for about a year (even getting my first CRT shock, while the power was on, that was fun!). I got bored of them, and eventually gave them to a friend. I never saw them again.
If I had access to the internet at that time, I probably could have figured it out, got them working etc.
Hindsight!
I love how when I bought my first Mac Classic (couldn't find a SE/30 here in Sweden) happened at the same time of those videos. Makes me even more enthusiastic about the repair process of recapping and so! 🎉❤
This mode is totally awesome 😎 I love those types of nerdy hack videos, makes my lunch time so much more enjoyable ❤
I love these hardwere hacks as well. Good work.
I remember reading the code name was OX for those Macs, pre-release, and how they considered diskless workstations, and balked at the last minute. The machine still came super under-configured, but boy did that disk image come in handy doing upgrades on that generation. Still no idea why Ox was its code name but word got out how to access it even tho it was considered a failed design option, they kept it in production. All that for Education marketing for some big Univ no doubt.
😵💫 my eyes went crossed trying to follow the explanation, but this was still fun to watch 😂
Congrats Adrian, you never know when and why it could come in handy to someone somewhere.
great job, nice to see an inspired video
Captivating, i want more such videos with experiments
Reminds me of the times when I was student and added memory in similar ways to my 520ST and casio FX850p.
I can totaly relate to the satisfaction of having the thing works !
Ha, that is so awesome! I am also a fan of hardware mods that make the computer more useful. Much like the Atari ST 4MB RAM upgrade video you did (which I also followed suit and did).
I have a Mega ST and there is a mod out there to connect 2x1MB 30 pin SIMMs instead of sourcing 16 x 1MB x 1 chips to get it to 4MB. That is next on my list! Great job!
Great video, what an interesting modification.
Great work Adrian, and very satisfying :) you have permission to engage ‘smug’ mode :)
Nice work Adrian!
There is nothing more satisfying than an idea come to fruition.
Oh yeah! Those Bomarc schematics SUUUUCK!!! I've tried using them before and found so many problems with them that they were utterly useless. I feel your pain.
Im working on an se30 right now, and they are terrible, I understand someone paid another to make them too.
Very cool Adrian! Now all you need is a custom case to make a mini-mac and cheese.