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 …
How do Z80 Block Transfer instructions work?
Jan 12, 2018 · The Z80 already had quite a high transistor count for the time. Implementing the ***R instructions the efficient way would have required implementing looping and/or branching logic in the …
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 …
z80 - Decoding Logic and Memory Systems for 8-bit computer - 64K ...
Apr 27, 2020 · I am creating a minimal Z80 computer with serial output on a breadboard. I have kind of moved up from the last question, where I was executing instructions on Z80 using specific …
Z80 - "LD (nn), dd" command cycle - Retrocomputing Stack Exchange
Apr 28, 2021 · Indeed, the Z80 manual is one of the most detailed with respect to the bus cycle descriptions and has definitely more interesting pages than the one you showed. You want to read …
Comparing Signed Numbers on Z80 (8080) in Assembly
Lots of problems using sign and overflow flags on Z80 for comparing signed numbers could be overcome in the following way: Just invert sign bits of both numbers prior to comparison, which will …
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.
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 …
Did underclocking the early Z80 chips improve yield?
Nov 16, 2022 · The Z80, one of the most successful and well-known of the 8-bit microprocessors, was released in July 1976 at an initial clock speed of 2.5 MHz. The TRS-80 Model I, released the …