Z80-512K - Z80 CPU, 512k ROM, 512k RAM, Clock and Reset Module

[Sergey Kiselev]

Hi,

I figured I never properly announced Z80-512K project here, which I completed back in January.

Z80-512K is an RC2014-compatible module designed to run RomWBW firmware. It combines functionality of the following RC2014 modules on a single module, thus saving space on the backplane:

- Z80 CPU Module

- 512k ROM 512k RAM Module

- Clock and Reset Module

In addition to these functions, Z80-512K includes programmable CLK2 clock divider, support for battery-backed SRAM, power failure NMI generation, and a watchdog.

Z80-512K is an open source project. Design files and documentation are available here: https://github.com/skiselev/Z80-512K

My Tindie store links:

* https://www.tindie.com/products/22683/ - Z80-512K PCB, CPLD, and optionally pre-programmed Flash ROM with RomWBW

* https://www.tindie.com/products/22682/ - Z80-512K Complete Kit

Cheers,

Sergey

[karlab]

Sergey

Great product for a small price. I am intrigued by the low component count and the use of programmed logic.

Programming logic is something I would like to learn but I dont know how to start.

Below you find my version of a compact module.

[karlab]

I send the post prematurely.Here is the picture.

On Friday, 16 April 2021 at 18:22:48 UTC+2 skis...@gmail.com wrote:

[Sergey Kiselev]

Karl,

That is a nice looking module. I assume Z180 based?

I can give you some ideas about using the programmable logic (CPLDs and SPLDs).... or perhaps, if there is an interest, I could do a Zoom or similar meeting, so more people can join?

Thanks,
Sergey

[Alan Cox]

On Fri, 16 Apr 2021 at 17:22, Sergey Kiselev <skis...@gmail.com> wrote:

Hi,

I figured I never properly announced Z80-512K project here, which I completed back in January.

Neat - it reminds me a lot of the later designs of Z80 system where all the glue mysteriously vanished into ULA chips and the like. Just needs a really bad TV output and a dodgy keyboard to complete 8)

I'll try and add it to the emulator and stick the baud rate support into Fuzix when I get back on it.

[Sergey Kiselev]

On Friday, April 16, 2021 at 11:53:14 AM UTC-7 etched...@gmail.com wrote:

Neat - it reminds me a lot of the later designs of Z80 system where all the glue mysteriously vanished into ULA chips and the like. Just needs a really bad TV output and a dodgy keyboard to complete 8)

Haha, except there is no mystery here... The VHDL files are in the repository :-) Now they might not look as visual as schematic, but Quartus II has an RTL view, which shows the logic gates, and that actually looks pretty cool.

I'll try and add it to the emulator and stick the baud rate support into Fuzix when I get back on it.

Sounds good. I wanted to give Fuzix a try on this platform, but I need to build a CTC or similar module for generating periodic interrupts first.

 

[karlab]

Hi Sergey

I was cheating using the Z180 :)

I love the idea of having a online session learning to do logic programming.

I also have to mention how important your contribution is to this community.

thank you!

Karl

[Wesley Isacks]

Both boards look fantastic! This kind of integration is right up my alley. I've spent an embarrassing amount of time trying to reduce the chip count of the 512/512 memory module...

I've gotten SPLDs figured out, but CPLDs continue to elude me (and I really want to learn them). Do they still involve a bunch of proprietary software?

-Wesley

[Bill Shen]

If you like integration but still want to use the original Z80 and 5V peripherals then 5V CPLD is definitely the way to go.  There are many ways of using CPLD.  I've recently learned that CPLD can also serve as a small but fast ROM which had fundamentally changed how I design retro computers.  ROM, serial port, CF interface and glue logic can all fit in a modest CPLD like ATF1504 (Altera EPM7064S equivalent)

I use Altera Quartus to design CPLD.  It is available as free download.

  Bill

[steveukman]

Awesome project and offer.  Count me in for the tutorial too.  I would like to 'move up' to CPLDs.

As a retro-compromise has anybody else used GALs?  As a more 'era-appropriate', through hole "look like DIL chips" I like them as an alternative to replace multiple gates (and handle late-stage fixes).  So far I have found the supplies good, PALASM under DosBox fairly easy, and the TL866 programmer handles them well.  Just curious to see if anybody else uses them.

My project is to have a Altair 8800 front panel controller for the RC2014 system (Mike Davis' panel and case controlling the RC2014).  80% there.  GALs have been really useful for 'external' decoding of the Z80 instructions (to detect stack operations, EI, DI, IACK cycles &c. for the more obscure status LEDs).  Probably the subject of a different post.

Thanks, Sergey for all of the inspirational contributions.

Steve

[Sergey Kiselev]

I did use SPLDs (GAL16V8/ATF18V8) in several projects: (MiniMax8085, Micro 8088, Easy Z80, and most recently Omega Home Computer. I use GALasm for compiling the fusemaps. I can give a quick tutorial on that.

For CPLDs I use Altera Quartus II, and then, if using Atmel CPLDs, I convert the POD files using POD2JED and program the CPLDs using ATMISP. While all these tools are proprietary, they are freely available.

--Sergey

[William Harrington]

Greetings,

I found an interesting book not too long ago since I am getting back into programmable logic for various projects.

ISBN-10: 0070578524

Programmable Logic Handbook

PLDs, CPLDs, & FPGAs

Ashok K. Sharma

Sincerely,

William Harrington

[Phillip Stevens]

Steve wrote:

Awesome project and offer.  Count me in for the tutorial too.  I would like to 'move up' to CPLDs.

As a retro-compromise has anybody else used GALs?  As a more 'era-appropriate', through hole "look like DIL chips" I like them as an alternative to replace multiple gates (and handle late-stage fixes).  So far I have found the supplies good, PALASM under DosBox fairly easy, and the TL866 programmer handles them well.  Just curious to see if anybody else uses them.

Hi Steve,

yes, I like the GAL devices too. The main reason I like working with them is that they can be programmed in CUPL language which (to me) looks a lot like C.

The WinCUPL tool is getting a bit long in the tooth and doesn't work with Windows 10. But it is easy to encourage to work with compatibility settings in Windows 10  or even easier with Linux Wine.

GALs are used to set the memory and I/O mapping for the YAZ180. And also to implement some logic around device selects and in-situ programming.

As you point out the TL-866 can handle them, so it is easy to maintain.

I also used a GAL to use as an experimental logic breadboard for the Turbo CPU Module. That way the timing signals could be worked out and improved after the hardware was designed.

Cheers, Phillip

[karlab]

Hi Sergey

I would really love attending your seminar in programming logic.

So if you decide to arrange something, I will attend.

Cheers

Karl