39 TTL Chips = Computer? Back to Breadboards - Minimal CPU Redux
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- Опубліковано 11 вер 2024
- I am wiring up an easy-to-build redux version of the 'Minimal CPU System' on breadboards. Enjoy!
Minimal CPU System:
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User Manual and Reference (Google Docs):
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It's a crime that you are seriously underrated. New sub here man. Don't stop making these educational videos, knowledge is everything homie.
Thanks man, glad you like what I show here. There ist some more stuff coming soon. Watch out for a full "80's style" home computer. 61 TTL chips. Cheers!
Thank you very much for all of your tremendous work! I've learned so much following your Minimal series. Now it's time to build up a system! :D
Sounds really great! The Minimal 64 is really fun to program on. I'd suggest try the emulator first which will come out soon.
I will try it on FPGA. Thanks for well illustrated diagram.
Cheers✨
Hi Ajinkya, would love to see what you can do with this design on FPGA. Please keep me posted.
Excellent work!
Good for you!
This is really impressive. I read through your documentation and this is a pretty solid load store architecture with minimal parts.
Amazing, the amount of work you have done here.
Just a hint for others: rather than using jumper wires, I use a different technique:
Loads of 10 pin male headers, break what is needed, push them in
AND SWITCH THE SOLDERING IRON ON - and connect the wires as needed - Module by Module and test them as you go along
SLU4, this is telepathy or what man!. Earlier this morning suddenly your Minimal crossed my mind so I compared to the other outstanding and large pipeline CPU built on PCB here on YT. because of simplicity, easy to follow and short videos (certainly lot of time for you as well) said to myself yours stands out. and now this! I saw it clear from the start, give it Gold Medal! congrats. Cheers.
Thanks for your kind words, Alessio! As always this means a lot to me and keeps me motivated :-)
I wish you had a longer video with the step by step breadboard setup.
@Slu4 Hello!
Wonderful to see such a thing come to fruition.
Can it play DOOM?
WOW! I have built a computer out of TTL chips and was only able to narrow down to a hundred or so ICs. I hope you are planning to put it on a PCB because I would like to build and play with the system myself, and learn how it works!
It depends - your CPU might have *much* more registers, address space and stuff. I search for these minimal requirements that just push a system into "useful space".
I would love to see all of the Data, Address, control, flags, Clocks , power on reset signals come out to an expansion buss so the "Minimal CPU System" community can start building expansion and I/O Devices for this wonderful Minimal computer. I'm getting a bit bored with these full blown computers nowadays, I want to touch the chips again !!
Hi X-OR, the 'Minimal' already has an expansion bus plus the logic needed to support it (INHIBIT signal) build in and I already have released a VGA card and and I/O card for this device. You may have to search my channel a bit ;-) Cheers!
@@slu467 Cool, I will check that out, Thanks!
This is definitely THE computer to use for restarting our civilization in a postapocalyptic world ;-) Great project and video Slu4.
This one is like a good old 1950s motorcycle - with two registers instead of wheels ;-) you can drive it everywhere and repair it on the fly.
+1 !!!!!
You forget that the memories used in this design are one to four *mega* bits, i.e. components that didn't exist until the 1990s. Early computers of the 1930/40s often had just a few hundred bits to play with.
@@herrbonk3635 You are right, but even with less RAM and without flash this design would still be useful.
@@glusiator Probably. Haven't checked how large the microcode is, but many of these TTL designs you see nowadays could have been used instead of early PCs and home computers, often with better performance. Using a microprocessor (that was basically intended for embedded systems) in early personal computers was more about fashion than technical reasons.
74-series ICs and CMOS RAM would probably not be more widely available than modern PC or mobile parts after the apocalypse though :) I guess it depends on where you dig. Starting from scratch would perhaps be more about extracting basic materials from rocks, and go on from there :)
Congratulations, you are the best
Plz if you can make a series from scratch on how to write the code, monitor, tetris...
Thanks, glad you like my stuff. I'll think about your suggestion, although such detail level is not everyone's cup of tea...
Hi Carsten,
Thanks for the tremendous effort you have put into your Minimal CPU! And, thanks for sharing its various incarnations with us through your fantastic UA-cam videos.
I think you can reduce the chip count by one by using a single 74HC4078 8-input OR/NOR instead of the 74HC4002 and 74HC08 combination in the ALU. These are available, reasonably priced, at, for example, eBay and elsewhere.
Be well & Best regards,
Gottfried
Hi Gottfried, thanks for diving into this and your suggestion. I am aware of the IC you mention, however, the design needs the other 3 ANDs of the 74HC08 anyway. So unfortunately that doesn't save anything ;-) Cheers!
@@slu467 Got it. Any chance you can show the schematics on your GitHub? (As you did for Release 1.5.) Perhaps, then, I wouldn't have missed the other use of the 74HC08. To be clear, that's on me.
Be well & Best regards,
Gottfried
@@gottfriedschuss5999 KiCAD schematics are already there. Will add some .pdfs soon ;-)
This is soooooo awesome!!
Interesting design, somewhat similar to what I used to teach at the university, uncomfortably long time ago. Horizontal microcode (lots of outputs), quite powerful. I was wondering, have you considered making the microcode more vertical, e.g. add decoders to microcode output bits and decrease the parallelism? Now you have a zillion of impossible combinations in the control. For example, you have 8 drivers for the internal data bus, so you could have just 3 control outputs in your microcode and use a 74HC138 to decode those 3 bits (Data Source Select [2:0]) to the 8 output enables you need.
On the other hand my thinking is clouded by the fact that back in the day when we would have made a CPU with discrete logic, memory (including PROMs and EPROMs) was ex-pen-sive! So we would have minimized the microcode ROM, which is kind of unnecessary today. Three large eproms is cheaper than all those demultiplexers and decoders. So, yeah, good job! Top marks!
Thanks for check out my design :-) actually you should check out my more recent videos on my channel. This design has evolved quite a bit and soon will become a full home computer with VGA out and PS2. 61 ICs. And it runs at 8MHz. At some stage I also thought about introducing decoders but they introduce extra time to the critical path and make a very fast design impossible. Cheers!
@@slu467 Thank you! Right, no contest here, as I stated: "Horizontal microcode, quite powerful".
I'm envious to you because you find the time to actually do, not just plan. I never have the time... :)
@@synestetic1687 My secret is having my daytime job not sucking up all my energy :-)
Very cool!
Slu4 makes Ben Eater look like a rookie.
was the discussion board deleted?
This project looks so cool, I think I'm gonna try to build one this year. Is there a PCB design for redux version @8MHz?
Hi Mateusz,
no, this is a breadboard version. But take a look at my recent design "Minimal 64". A nice PCB design will be available for that.
Great work! Was I not paying attention, or was there something of a shortage of decoupling caps on there?
Regarding bread-boards: I'm a make-a-pcb type myself (well, let JLC build it for me). At least that way I know that what I build is what I drew in the schematic... I've had a lot of problems with bread-boards over the years (fifty or more!).
Currently knocking together an 8080 from discrete logic; the simulation works so something might appear on UA-cam 'soon'.
Hi Neil,
I recommend putting 100nF on every power rail of the breadboards. Speaking of breadboards - I found is interesting to see if the system runs *without* any 100nF decoupling caps - and it didn't :-) but putting 2-3 caps back in place did the job. Cheers!
@@slu467 It doesn't take a lot, but you miss them when they're not there :) 10n at every chip's power supply seems to work for me (except for processors, where I follow the maker's instructions.
Using more control signals means that microcode can be little simpler. Is new version at least slightly faster ?
All it's missing is a text/graphics display and sound/music output.
Hi Stephen, you might have missed (see my earlier videos), that the Minimal has an expansion port and there is a VGA card available for it. You have a point with the audio out, though. Someone has to come up with a neat sound card ;-)
@@slu467 A couple of AY-8910's should do the trick. Go for stereo from the outset
Hi Slau4, where can i find it, where does each cable go, please? BOM file too
Please follow the links in the video description.
Thanks my friend
Do you have the pcb for a surface mount version of this design?
I have never tried my hand on SMD design. At least the 4 FLASHs need to be DIP or PLCC for re-programming. Cheers!
I mostly build my circuits on the breadboard. However, I find it very difficult to correct errors when something doesn't work. Especially when there are so many cables as in the video shown here (and on the picture here: www.dev-tronic.de/wp-content/uploads/2020/12/Z80Ardu_Breadboard_800.jpg). Quite apart from the side effects caused by interference.
The project itself is really great!