5 ms·

Why Z80? Is it like the 2nd most common processor type or something? Where would one find a Z80 when scavenging?

by jolmg 7y ago

garmaine 7y ago
TI calculator. Old school game boy.
- biztos 7y ago
  Dunno if this counts because I guess it's the "eZ80" but it looks like TI still makes one: https://education.ti.com/en/products/calculators/graphing-calculators/ti-84-plus-ce https://education.ti.com/en/products/calculators/graphing-ca...
  - garmaine 7y ago
    The TI-83 and TI-86 series calculators were Z80 based. Apparently they discontinued those in 2004. Huh. Maybe the m68k would be a better target? Actually if the OP is serious about this project, I would write base kernels for Z80, m68k, armv7, and RV32i. The last one isn't widely available, but has the advantage of being both modern architecture and allowing open-source specs for how to construct one from scratch.
    - collinmanderson 7y ago
      eZ80 in the TI-84 Plus CE (still manufactured) is backwards compatible with Z80 code. https://en.wikipedia.org/wiki/Zilog_eZ80 https://en.wikipedia.org/wiki/Zilog_eZ80
SwellJoe 7y ago
It's extremely common, even today, though probably not the processor I would pick (I think 68000 family, perhaps?), but it's probably a reasonable choice. You're going to be able to find it embedded in literally millions of devices and it's simple enough for one person to build a computer around it. I suspect the argument against modern Intel chips is just their complexity. They need an incredibly complicated and somewhat fragile support infrastructure...you can't build a modern PC motherboard in your garage and you don't expect modern PCs to last decades. They're very common, though, and I suspect there will be plenty of PCs to scavenge, at least through our lifetimes. But, the next generation will probably have trouble keeping them going...I've got a 40 year old C64 still running with nearly all original parts, but I am nearly 100% certain my modern laptop will not last even a decade without repairs using parts that can't be manufactured without modern infrastructure.
- jolmg 7y ago
  > I suspect the argument against modern Intel chips is just their complexity. Well that, and the fact that we already have plenty of OSes to run on x86(-64). Looking at arch/ in linux's source: alpha avr32 frv Kconfig microblaze openrisc score um arc blackfin h8300 m32r mips parisc sh unicore32 arm c6x hexagon m68k mn10300 powerpc sparc x86 arm64 cris ia64 metag nios2 s390 tile xtensa I'm surprised that it doesn't have support for Z80 if it's so common. I'm also surprised that I can't see mention of Z80 in GCC's documentation.
  - SwellJoe 7y ago
    No 6502, either. There aren't many 8 bit CPUs that are considered a reasonable platform for any UNIX. Which is why I think I'd prefer 68000 family. It's "modern enough" to use with modern compilers and operating systems, but simple enough for a one man garage shop to build/maintain a computer that uses it. I guess earlier 80x86 chips could fit that bill, too, but 68000 has a better assembly language.
    - lproven 7y ago
      The 68000 still did not have an onboard memory-management unit, though. The was only introduced with the 68030, which is roughly analagous and contemporaneous with the Intel 80386. The 68040 added an onboard FPU, like the 80486. (And like the 486SX, the 68040EC had the onboard FPU removed again.)
  - skykooler 7y ago
    The Z80 can't run Linux due to the lack of an MMU. (Though it's possible to get around that through emulation: see http://dmitry.gr/?r=05.Projects&proj=07.%20Linux%20on%208bit http://dmitry.gr/?r=05.Projects&proj=07.%20Linux%20on%208bit for example.)
    - LargoLasskhyfv 7y ago
      There is Fuzix. [1] http://www.fuzix.org/ http://www.fuzix.org/ And Symbos. [2] http://www.symbos.de/ http://www.symbos.de/ I wonder if he knows about them?

Why Z80? Is it like the 2nd most common processor type or something? Where would one find a Z80 when scavenging?

by jolmg 7y ago

Why Z80? Is it like the 2nd most common processor type or something? Where would one find a Z80 when scavenging?

garmaine 7y ago

TI calculator. Old school game boy.

biztos 7y ago
Dunno if this counts because I guess it's the "eZ80" but it looks like TI still makes one: https://education.ti.com/en/products/calculators/graphing-calculators/ti-84-plus-ce https://education.ti.com/en/products/calculators/graphing-ca...
- garmaine 7y ago
  The TI-83 and TI-86 series calculators were Z80 based. Apparently they discontinued those in 2004. Huh. Maybe the m68k would be a better target? Actually if the OP is serious about this project, I would write base kernels for Z80, m68k, armv7, and RV32i. The last one isn't widely available, but has the advantage of being both modern architecture and allowing open-source specs for how to construct one from scratch.
  - collinmanderson 7y ago
    eZ80 in the TI-84 Plus CE (still manufactured) is backwards compatible with Z80 code. https://en.wikipedia.org/wiki/Zilog_eZ80 https://en.wikipedia.org/wiki/Zilog_eZ80

SwellJoe 7y ago

It's extremely common, even today, though probably not the processor I would pick (I think 68000 family, perhaps?), but it's probably a reasonable choice. You're going to be able to find it embedded in literally millions of devices and it's simple enough for one person to build a computer around it. I suspect the argument against modern Intel chips is just their complexity. They need an incredibly complicated and somewhat fragile support infrastructure...you can't build a modern PC motherboard in your garage and you don't expect modern PCs to last decades. They're very common, though, and I suspect there will be plenty of PCs to scavenge, at least through our lifetimes. But, the next generation will probably have trouble keeping them going...I've got a 40 year old C64 still running with nearly all original parts, but I am nearly 100% certain my modern laptop will not last even a decade without repairs using parts that can't be manufactured without modern infrastructure.

jolmg 7y ago
> I suspect the argument against modern Intel chips is just their complexity. Well that, and the fact that we already have plenty of OSes to run on x86(-64). Looking at arch/ in linux's source: alpha avr32 frv Kconfig microblaze openrisc score um arc blackfin h8300 m32r mips parisc sh unicore32 arm c6x hexagon m68k mn10300 powerpc sparc x86 arm64 cris ia64 metag nios2 s390 tile xtensa I'm surprised that it doesn't have support for Z80 if it's so common. I'm also surprised that I can't see mention of Z80 in GCC's documentation.
- SwellJoe 7y ago
  No 6502, either. There aren't many 8 bit CPUs that are considered a reasonable platform for any UNIX. Which is why I think I'd prefer 68000 family. It's "modern enough" to use with modern compilers and operating systems, but simple enough for a one man garage shop to build/maintain a computer that uses it. I guess earlier 80x86 chips could fit that bill, too, but 68000 has a better assembly language.
  - lproven 7y ago
    The 68000 still did not have an onboard memory-management unit, though. The was only introduced with the 68030, which is roughly analagous and contemporaneous with the Intel 80386. The 68040 added an onboard FPU, like the 80486. (And like the 486SX, the 68040EC had the onboard FPU removed again.)
- skykooler 7y ago
  The Z80 can't run Linux due to the lack of an MMU. (Though it's possible to get around that through emulation: see http://dmitry.gr/?r=05.Projects&proj=07.%20Linux%20on%208bit http://dmitry.gr/?r=05.Projects&proj=07.%20Linux%20on%208bit for example.)
  - LargoLasskhyfv 7y ago
    There is Fuzix. [1] http://www.fuzix.org/ http://www.fuzix.org/ And Symbos. [2] http://www.symbos.de/ http://www.symbos.de/ I wonder if he knows about them?