How did the Z80 instruction set differ from the 8080?
Oct 26, 2016 · The Zilog Z80 microprocessor, known for its use in the ZX Spectrum, was designed to be a backwards-compatible extension to the Intel 8080 processor. It introduced several new instructions …
Comparing raw performance of the Z80 and the 6502
May 21, 2022 · The Z80's fastest memory fetch — the first half of an operation fetch — takes two cycles. That's always paired with another two cycles for refresh though, so the shortest instructions are four …
Is there any way to read current Interrupt Mode in Z80 machine code?
Apr 13, 2024 · The Mirage Microdriver (a snapshot device for the ZX Spectrum) needs to record the current interrupt mode when a snapshot is made. It does this by setting I to 80h and storing the …
design choices - What is the purpose of the M1 pin on a Z80 ...
Jun 24, 2024 · 9 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", …
What was the last commercial Z80-based computer sold?
Jul 13, 2025 · AFAICT, the last Z80 desktop computer sold was the TRS-80 Model 4, in production until late 1991. If you include notebook computers, the Amstrad NC200 was released in 1993.
z80 - What is R register and DRAM refresh internal operation ...
Apr 14, 2024 · The Z80 CPU has a built-in feature to support refreshing DRAM memory, by keeping a 7-bit refresh counter in the register R. The refresh counter is increased by 1 after every instruction …
Managing registers/memory effectively on the Z80
Feb 17, 2023 · The Z80 assembler unified the mnemonics to a great extent. Its rather abstract angle simplifies first steps. In contrast 8080 mnemonics are more diverse, if not chatty, presenting more of …
Why is Z80 called a 8-bit CPU? - Retrocomputing Stack Exchange
Mar 17, 2024 · The Z80 fetches, processes and stores 8 bit at a time. Z80 has a 16-bit address bus If address bus would be a relevant measure to classify a CPU, then 8088 would be not 16 but 20 bit …
Did any computers use the Z80B? - Retrocomputing Stack Exchange
Jan 10, 2018 · The Z80 was one of the most popular CPUs of the seventies and eighties. In almost all cases that I know of, the version used was the Z80A, rated for 4 MHz, sometimes clocked a little …
What are some tracing disassemblers for the Z80
Apr 17, 2024 · 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 …