Questions tagged [z80]
The Zilog Z80 microprocessor. Prefer [game-boy] instead for questions about the Game Boy CPU nicknamed the ‘GBZ80’.
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Are a Z80 address pins tristate?
I been looking at the Z80 CPU recently and am wondering how difficult it would be to wire one up. The thing I'm interested in is how to connect it to some RAM. In particular, I'd like to know if the ...
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How to best use IX as a return stack
I'm new to Z80 assembler and am porting a Forth interpreter from a J1 stack machine to a Z80 based board. The Z80 port uses SP for the data stack, and IX for the return stack.
The port uses a normal ...
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What is the purpose of the M1 pin on a Z80
I've been looking through bits of documentation about the (sadly recently discontinued) Z80 processor and the machines people have built with it. One thing I noticed is pin 27, called "M1", ...
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NES vs SMS ROM speed
The NES used a 6502-derived CPU at 1.79 MHz.
The Sega Master System used a Z80 at 3.58 MHz.
How did they differ in terms of what speed grade ROM they required in their respective cartridges? I know it'...
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ASM as a DSL of a HLL? [closed]
There used to be a lot of discussion as regards embedding DSLs (Domain Specific Languages) into high-level languages (HLLs). The only example, where this is possible, I know of, is c++ and I had ...
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What are some tracing disassemblers for the Z80
What are some some tracing disassemblers for the Z80? I.e., disassemblers that will trace through the code and disassemble as instructions only the areas it traces through, leaving the rest as data. (...
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What is R register and DRAM refresh internal operation
Resources say that R value gets incremented by Z80 after each M-cycle, and that R is used in Dynamic RAM refresh mechanism (avoiding charge leakage).
My questions:
how concrete value of R (say, #11) ...
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Is there any way to read current Interrupt Mode in Z80 machine code?
Is there any way to read current Interrupt Mode in Z80 machine code?
Official Z80 datasheet mentions IMFa/IMFb registers which keep the mode value.
Thank you
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Does Altair Basic actually risk wiping itself out of memory in its auto-memsize initialization?
I've recently designed and built a modern Z80 single board computer based on a Z80 IPC chip.
It's general purpose, and though I did not design it for compatibility to Altairs, I decided that my first ...
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Why is Z80 called a 8-bit CPU? [duplicate]
Z80 has a 16-bit address bus and 16-bit arithmetic instructions such as add hl,de. Why is it still called a 8-bit CPU?
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Change text color in Z80 assembly for Amstrad CPC 464
I am trying to code this program, similar to game: "The Typing of The Dead" in Amstrad CPC 464 using Assembly language for the Z80 processor.
The program consists in when you see a string of ...
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Size-optimization of a 256-byte "LDIR" adapter
I'm working on tweaking ABC-800 BASIC II machine code, and there's a routine there that does a "256-byte" equivalent of LDIR. B is not used, C=0 transfers 256 bytes, C=1 transfers 1 byte, ...
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Do Z80 datalines need termination [closed]
If I am using a z80 can you just tie all data lines to the ROM 28c16 or do they need termination via 10k ohm resistors to ground?
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Compressing a list of records so it can be uncompressed elementwise [closed]
I have a bunch of lists of generic items (byte sequences) and I would like to store them compressed. There are several tools out there that run on modern computers to compress data into as-small-as-...
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ZX Spectrum+ 48K with faulty memory writing address
I have ZX Spectrum+ 48k (board issue 6a) with writing to memory issue.
When I try to write a value by POKE command to address 49152 (C000h) then it overwrites additionally value with address 16384 (...
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