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 · It is said the Z80 has a typical 4 clock ticks per instruction, while the 6502 has typically 1 clock tick per instruction and a rudimentary pipeline. It is said the Z80 ALU internally, is 4 bits when the 6502 ALU is 8 bits. It is said the z80 accesses memory every 4 clock ticks, while the 6502 accesses memory every 2 clock ticks.

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 ...

2019年3月30日 · extra pins every Z80-world compatible peripheral has to have. extra intelligence every such a peripheral has to have: particularly, they have to understand specific Z80 command (that is, RETI), whose the only purpose is to say to the peripherals the interrupt routine ends; otherwise RETI is fully equivalent to RET.

2018年6月5日 · The Z80 includes two ALUs: a 4-bit general-purpose one, and a 16-bit increment/decrement circuit. Having recently found out about that, I find myself curious how much circuitry would have been needed to allow the inc/dec to add or subtract 256 rather than 1, and use that to expedite the s8+16 arithmetic used in "jr" or the indexed addressing modes.

2019年3月21日 · A Z80 with a PIO can do everything (*1) a separate system can do. In this case it needs 4 port bits. Two for receiving data/clock from the keyboard/mouse, two to overwrite these to initiate an output sequence and control output data.

2017年11月24日 · Back in 1995, I used to work on satellite on-board-systems that were typically powered by a number of 1MHz Z80 forming what you would today call a multi-core CPU. The Z80 communicated through shared memory segments and worked out complex fixed-point calculation for earth observation, radar range measurement, and general telemetry.

2018年1月12日 · Comparing Z80 with 6809 we should take into account difference in first production date which leads to technology difference (feature size) and thus to difference in the number of transistors that were available to the designers, as well as the fact that Z80 traditionally has higher clock rates than 6502-likes and 6809-likes, thus making the ...

2018年11月5日 · Putting automatic objects on the stack is a horribly inefficient way of handling them on the 8080 and Z80 unless it is necessary to support recursion or reentrancy. 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 ...