5 ms·

6502 > Z80

by spintin 2y ago

6502 > Z80

renewedrebecca 2y ago
For what?
- wizzwizz4 2y ago
  Video without RAM contention, for one: https://retrocomputing.stackexchange.com/q/22257/278 https://retrocomputing.stackexchange.com/q/22257/278 > The 6502 needs access to memory only half the time, during the what is usually called the ϕ2 phase of the clock. The other half of the time, so long as you tri-state the CPU address pins,² the bus and memory are available to other systems. > The Z80 does not have such a well-defined, synchronous system of accessing RAM. Many cycles don't need RAM access, but many do, and which particular ones do and do not depend on the instruction mix. > There is no "do nothing" solution to this constraint, and Z80-based systems that wanted consistent video output would have to solve this one way (hardware) or the other (software).
  - renewedrebecca 2y ago
    So, any feature of a processor is a reason to say something is better than the other? Ok... The 6502 does not have port-I/O. Everything is memory mapped. Therefore, the Z80 is better. Or, the Z80 has more registers than the 6502, therefore the Z80 is better. Or, the Z80 can do limited 16-bit operations that the 6502 can't, therefore the Z80 is better.
- vardump 2y ago
  At same clock frequency 6502 is quite a bit faster.
  - mister_handy 2y ago
    For some workloads, the 6502 was faster than a more-typical 4Mhz Z80.
  - renewedrebecca 2y ago
    Sure, but how many 1 Mhz z80 machines do you remember? I'm not saying the z80 is better than the 6502, but it's a pretty big stretch to say the 6502 is better, especially if you're not coding in assembler.
- deleted 2y ago
  [deleted]
mister_handy 2y ago
Well, it's the last actual MPU from that era, so from the perspective of "you will still be able to buy them when existing stock runs out," sure. Otherwise, there's no clear winner.
karmakaze 2y ago
I would say 6502 < Z80 (cheaper in a good way leaving more for graphics+sound support chips). The first time I used dBase II on a Xerox C/PM machine was when I realized what a business computer could be like. It seemed standardized more than the PETs or TRS80s.

6502 > Z80

renewedrebecca 2y ago

For what?

wizzwizz4 2y ago
Video without RAM contention, for one: https://retrocomputing.stackexchange.com/q/22257/278 https://retrocomputing.stackexchange.com/q/22257/278 > The 6502 needs access to memory only half the time, during the what is usually called the ϕ2 phase of the clock. The other half of the time, so long as you tri-state the CPU address pins,² the bus and memory are available to other systems. > The Z80 does not have such a well-defined, synchronous system of accessing RAM. Many cycles don't need RAM access, but many do, and which particular ones do and do not depend on the instruction mix. > There is no "do nothing" solution to this constraint, and Z80-based systems that wanted consistent video output would have to solve this one way (hardware) or the other (software).
- renewedrebecca 2y ago
  So, any feature of a processor is a reason to say something is better than the other? Ok... The 6502 does not have port-I/O. Everything is memory mapped. Therefore, the Z80 is better. Or, the Z80 has more registers than the 6502, therefore the Z80 is better. Or, the Z80 can do limited 16-bit operations that the 6502 can't, therefore the Z80 is better.
vardump 2y ago
At same clock frequency 6502 is quite a bit faster.
- mister_handy 2y ago
  For some workloads, the 6502 was faster than a more-typical 4Mhz Z80.
- renewedrebecca 2y ago
  Sure, but how many 1 Mhz z80 machines do you remember? I'm not saying the z80 is better than the 6502, but it's a pretty big stretch to say the 6502 is better, especially if you're not coding in assembler.
deleted 2y ago
[deleted]

mister_handy 2y ago

Well, it's the last actual MPU from that era, so from the perspective of "you will still be able to buy them when existing stock runs out," sure. Otherwise, there's no clear winner.

karmakaze 2y ago

I would say 6502 < Z80 (cheaper in a good way leaving more for graphics+sound support chips). The first time I used dBase II on a Xerox C/PM machine was when I realized what a business computer could be like. It seemed standardized more than the PETs or TRS80s.