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Pony80 - 64K Memory Module BUILD - My Z80 homebrew computer!
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- čas přidán 30. 09. 2022
- In this video, I will be building the 64K RAM/ROM memory module for the computer.
It includes the ability to page out ROM and have the entire 64K of RAM.
This was a huge build and a long video, but now that it is complete, we have a working, programmable computer!!!
"A floating pin is never a good thing!"
The Pony80 is a Z80 based 8-bit computer that I built from scratch.
In this series, I will be taking a deep dive into everything I wish I had known before starting!
PASMO Z80 assembler: pasmo.speccy.org/
Link to the EEPROM burner that I am using: amzn.to/3USjCXA
Please visit my website. I have links and schematics for the videos I’ve released and much more!
ponytailbob.com/pony80-memory...
Also, visit my Patreon site. I have extra content and behind the scenes videos for my patrons.
/ ponytailbob
![[STE] Decimal up-counter using 74LS48 and 74LS86 driven by a symmetrical squarewave](/img/n.gif)
Great video. I just ordered a static ram to play with, arrived today. Then this video popped up and you are using the exactsame chip ... lol. I am just getting back into the hobby, never did use a static ram, they were super expensive 40 years ago. I did do a breadboard memory upgrade for my Trs80 Model 1 using 64k x 1 dynamic ram chips. I only used half the memory. A lot of wires and it surprisingly worked. Got my z80 on order for some future use, not sure what yet.
Thanks for covering the entire process and leaving the errors in 🙂
Thanks for the update. You inspired me to make my own Z80 computer, I ended up building mine on a z50 backplane, it made life much easier! I also ended up using a GAL for the decoding on a separate board with basically the same IC's. I was initially using 138 data selectors, but found having reprogrammable logic helped me troubleshoot a touch.
Looking forward to where your project goes from here, I've hooked up an LCD and PS2 keyboard. (I've had an endless stream of issues with the interrupt line!)
That is awesome! That is exactly why I am doing this. Hoping to inspire others!
@Aaron, I'm also very likely going to do my decoding with a GAL. I'm curious, why did you choose the Z50 backplane?
@@microhobbyist Because a friend had one spare locally. I don't regret it. Having all the pins broken out and good connections between the CPU and RAM/ROM has made the system so much more stable. I found on breadboard if the CPU wasn't running properly it was a 50/50 chance it was the breadboard or the code.
This content is awesome. I am setting out to create a collaborative z80 game console project with my 8 year old Son. Your tutorials are perfect for us to learn the basics right through to more advanced concepts. ✨️ Thank you!
Glad to hear it! Getting ready to put out a few more videos about programming and PCB creation. Stay tuned!
36:57 For the RAM chip, you don't have to match the Address or Data lines exactly.
Lets say you flip the databus. Sure data will be written flipped but it will be unflipped when read back out. same for address lines.
Fascinating series of videos. Can't wait to see the rest. I'm also doing my own series on the Z80 that I just started. Have a look?
Good job! I was going to build a 6502, but for some reason I got sidetracked with the Z80.
@@Pony80
HAHA, that's what always happens doesn't it
You're either a guy that jumps on 6502 or you're a guy that jumps onto Z80 , Says he's gonna move onto 6502 but you never do LOL
it's funny, the Z80 is that cool that you don't move onto 6502
i understand you can page 255 time from one IO and there 255 IO
so if you have 8k rom and magic rest use 56k ram and paging ram
you can have 3641.4 MB/3.6GB ram 255*255*56k on z80 if you want build damn thing lol and program some software to use it. mayby notepad LOL and we did not need page rom at all xD rom you have your notepad that use pages of ram to write huge book xD
So simple and basic. A simple logic probe will save you a lot of trouble when it comes to tracking down poor or bad connections. The Z80 is good for control applications. Personally I'd forget about trying to maximize ram by bank switching. Thats a poor technique and adds unnecessary complexity. figure 1 or 2k for the stack and another 1k for IRQs. When you start writing assembly language or binary to memory by hand you'll find 64k is plenty of ram. I think when everything is said and done your entire program plus the ram required for temporary data storage is going to be way under 8k, probably in the 2 or 3k range plus an extra 1k for temporary storage. I'd consider a few 74ls373's to monitor the control and status signals of the cpu, and setting up a way to single step the cpu. I don't want to rain on your parade but I don't see a single decoupling capacitor on the board. I say those are necessary unless you want random problems occurring in the execution of your program. Remember the CPU has a fanout of 1, an important consideration when designing a computer with a lot of chips connected to the address and data bus. Personally I'd think about using a single 64kx8 static ram, and using a Raspberry pi or pi pico to put the cpu into the high impedance state and writing the code directly into ram by having the pi take control and perform a DMA operation. That's just me. It's your baby so you can do it anyway you want. I've done quite a few of these in the past, but my advice and or criticism will only get you a cup of coffee if I have 2 bucks to go with it. Don't let anyone get your feathers up. Never accept criticism from anyone you wouldn't take advice from. That's always worked for me. Don't get stuck thinking there's only one way to do something. I've been down that road. Maybe sometime in the future you'll consider using the MC68000 for a project after you've done a few Z80 projects. Peace out dude.
Thanks for all the great advice and support!!! Super cool comments!
7:50 ... ?
I had to watch that three times to see what's up, your red LED is behind a red wire.
Lol, didn’t notice that!