2016年10月26日 · 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 to the 8080's instruction set, as well as adding or extending registers.

2020年2月16日 · Looking at the development and architecture of the Z80, it appears to be a scaled-down, cost-reduced (in terms of total system cost), clone of the Intel 8080. It only used a 4-bit ALU. I assume this would have reduced its performance considerably. However, the Z80 out performed the Intel version and nearly displaced it completely in the CP/M ...

2022年5月21日 · A lot has been said on the internet about the 6502, at 1MHz, being roughly equivalent in performance to the Z80, at 4 MHz. It is said the Z80 has a typical 4 clock ticks per instruction, while the ...

2023年2月17日 · The Z80 was designed as an 8080 clone with most instruction set extensions being more targeted at sales than usage. So there's the reason why most CP/M software stayed with 8080 code, despite the Z80 having replaced it in new machines within less than a year.

2019年3月30日 · The short answer is that Z80 do NOT determine itself which peripheral sends an interrupt. In Zilog's framework, all compatible peripherals determine among themselves who's emitting the interrupt to the CPU this time. Or more specifically, who is sending IM2 vector on the bus during the time Z80 acknowledges the interrupt.

2024年4月14日 · 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 opcode fetch, and after the instruction opcode has been fetched and being decoded, the idle time on the bus is used to do a refresh bus cycle with the register ...

2018年1月12日 · 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 instruction decode circuitry making it much more complex.

2018年11月5日 · Copying the stack pointer to IX on function entry and then using IX to access automatic objects is somewhat reasonable from a code-size perspective, but the Z80's 4-bit ALU makes it very slow to process address arithmetic.

2017年11月24日 · What were the fastest CP/M computers ever built? I'll restrict this to the Z80 variant of CP/M, no CP/M-86, CP/M-68k etc. Z80 compatibles with higher clock frequencies or more instructions/clock or other modifications count, as long as it ran CP/M using mostly the Z80 ISA. Overclocked homebrew systems count.

2017年9月10日 · Was there ever a commercially available hobbyist/teaching computer with the ability to single-step the processor? Maybe a Z80-based machine?