4 ms·

A small part of me was hoping this would contain 16x physical through-hole Z80 chips. Alas, 'tis FPGA.

HocusLocus 7y ago
Or if it was "discovered" that bending the Z80 pins inward a bit and stacking them 16 high over each other actually works, and would have worked even back in the 70s. That would be surreal.
- jacquesm 7y ago
  I did that with memory on more than one occasion. Stacking them more than 4 high they'd tend to overheat.
  - boomlinde 7y ago
    Wouldn't you have to at least wire the chip select pins somewhere distinct for that to work? I know little about electronics.
    - jacquesm 7y ago
      Yes, exactly that, you bend out one pin per chip and wire that up to some decoding logic. But all of the other pins are parallel.
anonymousiam 7y ago
As far as I know, the fastest production Z-80 chip (the Z-80H) ran at 8MHz. This one runs at 84MHz per CPU! I switched from 8-bit (Z-80B) hardware to 16-bit (i386) hardware once the 16-bit PC could emulate the Z-80 faster than any physical Z-80 processor could run. I feel fortunate to have skipped the 8088 and 80286 PCs which all ran slower than my Z-80B for most things. I kept one of my old CP/M machines in my parent's garage for 10 years, and then tried to resurrect it. It was an IMSAI 8080 with CompuPro hardware that I had modified to allow the front panel to work while allowing the system to run at 4MHz. I had also implemented software configurable baud rate and start/stop/parity selection by hacking the hardware and customizing the BIOS. Unfortunately when I resurrected it, it booted and ran for only a short time before the ST851 hard drives scraped the oxide coating from the system disks. (I destroyed all of the backups while troubleshooting.) I gave the whole system away before I discovered that they are actually still quite valuable, but I have no regrets. I much prefer a more modern computer.
- chipotle_coyote 7y ago
  If you expand that to Z80 compatible chips, the fastest was (is, possibly, as I think it's still being made) the Zilog eZ280 at 50 MHz -- which, given that it runs at about three times as fast as the Z80 at the same clock frequency, is like having a 150 MHz Z80. https://en.wikipedia.org/wiki/Zilog_eZ80 https://en.wikipedia.org/wiki/Zilog_eZ80 My TRS-80 Model 4 back in the day (circa 1988, I think) had been upgraded with a HD64180 CPU, which apparently could run at least at 10 MHz -- although I'm pretty sure the third-party expansion board I was using ran it at 6.144 MHz.
  - Gracana 7y ago
    You may be aware, but to add to your comment... Good ol' Z80s are still in active production as well, and you can buy a 20MHz chip in a DIP, LQFP, or PLCC package. Anyone who is interested should check out the RC2014 and retrocomp google groups. Lots of discussion there, and there are a few people selling Z80 and Z180 computer kits. https://groups.google.com/forum/#!forum/rc2014-z80 https://groups.google.com/forum/#!forum/rc2014-z80 https://groups.google.com/forum/#!forum/retro-comp https://groups.google.com/forum/#!forum/retro-comp
- dragonwriter 7y ago
  > I switched from 8-bit (Z-80B) hardware to 16-bit (i386) hardware once the 16-bit PC could emulate the Z-80 faster than any physical Z-80 processor could run. Isn't the i386 the first 32-bit x86 processor, not 16-bit?
  - anonymousiam 7y ago
    The 386SX was a 16-bit CPU capable of 32-bit operations. Think of it in the same context as the 8088 vs. 8086.
    - dragonwriter 7y ago
      As I recall, it was a low cost 32-bit CPU essentially identical to the original 80386 (subsequently rebranded 80386DX to further distinguish it from the SX) which was introduced several years earlier and is the main CPU referred to when people say i386 without qualification, except that it had a 16-bit data bus and a 24-bit address bus. > Think of it in the same context as the 8088 vs. 8086. Yes, both of those are 16-bit but the 8088 is a later low-cost version with an 8-bit data bus, but an identical execution unit to the 8086.

Or if it was "discovered" that bending the Z80 pins inward a bit and stacking them 16 high over each other actually works, and would have worked even back in the 70s. That would be surreal.

jacquesm 7y ago
I did that with memory on more than one occasion. Stacking them more than 4 high they'd tend to overheat.
- boomlinde 7y ago
  Wouldn't you have to at least wire the chip select pins somewhere distinct for that to work? I know little about electronics.
  - jacquesm 7y ago
    Yes, exactly that, you bend out one pin per chip and wire that up to some decoding logic. But all of the other pins are parallel.

anonymousiam 7y ago

As far as I know, the fastest production Z-80 chip (the Z-80H) ran at 8MHz. This one runs at 84MHz per CPU! I switched from 8-bit (Z-80B) hardware to 16-bit (i386) hardware once the 16-bit PC could emulate the Z-80 faster than any physical Z-80 processor could run. I feel fortunate to have skipped the 8088 and 80286 PCs which all ran slower than my Z-80B for most things. I kept one of my old CP/M machines in my parent's garage for 10 years, and then tried to resurrect it. It was an IMSAI 8080 with CompuPro hardware that I had modified to allow the front panel to work while allowing the system to run at 4MHz. I had also implemented software configurable baud rate and start/stop/parity selection by hacking the hardware and customizing the BIOS. Unfortunately when I resurrected it, it booted and ran for only a short time before the ST851 hard drives scraped the oxide coating from the system disks. (I destroyed all of the backups while troubleshooting.) I gave the whole system away before I discovered that they are actually still quite valuable, but I have no regrets. I much prefer a more modern computer.

chipotle_coyote 7y ago
If you expand that to Z80 compatible chips, the fastest was (is, possibly, as I think it's still being made) the Zilog eZ280 at 50 MHz -- which, given that it runs at about three times as fast as the Z80 at the same clock frequency, is like having a 150 MHz Z80. https://en.wikipedia.org/wiki/Zilog_eZ80 https://en.wikipedia.org/wiki/Zilog_eZ80 My TRS-80 Model 4 back in the day (circa 1988, I think) had been upgraded with a HD64180 CPU, which apparently could run at least at 10 MHz -- although I'm pretty sure the third-party expansion board I was using ran it at 6.144 MHz.
- Gracana 7y ago
  You may be aware, but to add to your comment... Good ol' Z80s are still in active production as well, and you can buy a 20MHz chip in a DIP, LQFP, or PLCC package. Anyone who is interested should check out the RC2014 and retrocomp google groups. Lots of discussion there, and there are a few people selling Z80 and Z180 computer kits. https://groups.google.com/forum/#!forum/rc2014-z80 https://groups.google.com/forum/#!forum/rc2014-z80 https://groups.google.com/forum/#!forum/retro-comp https://groups.google.com/forum/#!forum/retro-comp
dragonwriter 7y ago
> I switched from 8-bit (Z-80B) hardware to 16-bit (i386) hardware once the 16-bit PC could emulate the Z-80 faster than any physical Z-80 processor could run. Isn't the i386 the first 32-bit x86 processor, not 16-bit?
- anonymousiam 7y ago
  The 386SX was a 16-bit CPU capable of 32-bit operations. Think of it in the same context as the 8088 vs. 8086.
  - dragonwriter 7y ago
    As I recall, it was a low cost 32-bit CPU essentially identical to the original 80386 (subsequently rebranded 80386DX to further distinguish it from the SX) which was introduced several years earlier and is the main CPU referred to when people say i386 without qualification, except that it had a 16-bit data bus and a 24-bit address bus. > Think of it in the same context as the 8088 vs. 8086. Yes, both of those are 16-bit but the 8088 is a later low-cost version with an 8-bit data bus, but an identical execution unit to the 8086.