29 votes
Accepted

Wiring a Zilog Z80

The MK 3880 Mostek CPU Technical manual (it's the Z80 implementation from Mostek) has a section called "Hardware implementation examples" which may help you. Besides, the Thomas Scherrer Z80-Family ...
18 votes
Accepted

Z80 is making weird relative jump errors. How can that be?

I thank Raffzahn for his teaching me some Z80 basics, which indeed I don't have. But on the main issue that I was pulling my hair out over, I think I found the problem. There appears to be an issue ...
14 votes

Z80 is making weird relative jump errors. How can that be?

I'm not sure, but this does look a bit like the typical trap programmers fall for when coming from CPUs that set flags according to data handled: 0004 DB 00 IN A, (0) ; input a ...
  • 184k
12 votes
Accepted

Smallest/Simplest, modern pure relay computer with at least 4-bits data words

How about a Turing machine implemented with relays? If I didn't miscount, there are 8 relays plus 1 relay for each bit of the state (for a total of 12 with 4-bit state). Let's see your conditions: ...
  • 22.9k
10 votes

z80 crashes after executing some instructions

You might be having some sort of short between A7 and some other CPU line. Your program doesn't use/need this line, but refresh does. The fact that "weird behavior" starts when A7 is toggled for the ...
  • 29.1k
9 votes
Accepted

z80 crashes after executing some instructions

Found the actual problem (i believe). I was used to connecting rom's /CS to A15 to have both a rom and a ram later on, on a 6502 system but as it turns out there is a handy /MREQ signal on the Z80....
  • 394
9 votes

z80 crashes after executing some instructions

There is a lot what could go wrong here a list of hints: code I see no ORG directive in the code so are you sure you are placing your code in the right place of memory? Also I would feel safer with ...
  • 7,016
9 votes

Homemade ROM cartridge for Thomson TO7/70 home computer

It's funny you should ask this now, Daniel (who runs the site you found the ROMs and schematic on) and Phil (another 8-bit enthusiast) recently produced an EEPROM-based PCB for exactly this purpose. ...
9 votes
Accepted

Can you program an arcade game and have MAME or another emu run it?

Games have "sets" (AKA versions). The software changes but not the hardware. For instance Pengo set 2 is harder than set 1 and has a different music (to avoid lawsuits?) If you can "mod" an existing ...
8 votes

Wiring a Zilog Z80

IMHO, the easiest way to make that lonely Z80 into something you can play with is to hitch it to an Arduino. The Arduino can generate the clock, control the data lines, operate some of the control ...
8 votes

Smallest/Simplest, modern pure relay computer with at least 4-bits data words

I just found this discussion and I wanted to correct a few mistakes by Jules about one of my projects, the YGREC8 (I'm the YG of YGREC). There are many relay-based projects, look at https://hackaday....
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7 votes

Homemade ROM cartridge for Thomson TO7/70 home computer

As an alternative to your project, you can use The Mégarom T.2, it's a MEMO7 Cartridge for Thomson T9000, TO7, TO7/70, TO8, TO8D, TO9, TO9+. It contains 70 softwares. Another way is to use the SDDRIVE ...
7 votes

Smallest/Simplest, modern pure relay computer with at least 4-bits data words

Neither of these are quite what you're looking for, but I'm including them because I think they're worth looking at nonetheless, and I think both are more interesting than the designs you've linked ...
  • 12.5k
6 votes
Accepted

Commodore 64 board dimensions

There are several revisions of the C-64 board (see, e.g., here , or here), with two major form factors: the old "long board" and the new "short board". The long board (which I happen to have on my ...
  • 8,782
6 votes

How to teach the Z80 to count milliseconds and microseconds like Arduino?

Way 2.1 to pin a non-masked interrupt, attach a crystal with a frequency of 10KHz (not sure about this value, but with another value idea is same), and in the non-masked interrupt handler, increase ...
  • 3,014
5 votes
Accepted

Can't get the AY-3-8913 sound chip to work with my z80 (added schematic)

Brief look shows that you use [A15:A8] in circuit feeding CS pin; Z80 is having only 256 distinctive ports controlled by OUT command family, thus you must drop [A15:A8] out of the equation. Please ...
  • 1,228
5 votes

How to teach the Z80 to count milliseconds and microseconds like Arduino?

You have correctly surmised the two approaches to measuring time, not just on the Z80 but in computers in general. With a processor like the Z80 where every instruction takes a known number of ...
  • 11.8k
5 votes
Accepted

Is there a KiCad library with parts used in retrocomputers?

People do use KiCad for this job! The S100 Computers group have created many, many boards using KiCad (included in the list here) and provide the KiCad files used to create each of them. Including the ...
  • 18k
4 votes

How to I give instructions to a Z80 CPU

Unless you want to build a barebones/simple computer basically from scratch, I'm not sure there's really much you can do with just a CPU chip on its own. Maybe there are some simple tests you can run ...
  • 1,702
4 votes
Accepted

How to teach the Z80 to count milliseconds and microseconds like Arduino?

Now I'm stuck - I need to be able to count milliseconds and microseconds in the code. Forget about microseconds. Single instructions on a Z80 are already in the range of 1 µs or even longer, ...
  • 184k
3 votes

Are there any homebrew games (or demos) for the Timex/Sinclair 2068?

I present here the first World Museum about the ZX Spectrum, with many information about the Timex clones: https://loadzx.com/en/ https://www.facebook.com/LoadZXSpectrum/ Another info: 1 - The ...
2 votes

How to teach the Z80 to count milliseconds and microseconds like Arduino?

your best bet would be to hook up binary counter directly to your CPU clock and use it as divider that creates interrupt ... For example if you got 4.0MHz and want ~1ms resolution then divide the ...
  • 7,016
2 votes

Wiring a Zilog Z80

There are a lot of easy and simple constructions, based on the Z80 CPU. I prefer the simple Grant Searle's Computer. If you prefer the more simple way, you could try the ready-made solution, like the ...
  • 5,257
1 vote

Z80 is making weird relative jump errors. How can that be?

Not an answer to the question, but a suggestion: You said a couple of times that you don't have a scope. Well, get one. You can buy tiny DS0138 digital scope kit for literally pocket change, AND it ...

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