My hardware is an eZ80F91 ASSP CPU at 50MHz (but I used a 50MHz oscillator, the PLL is unused) with SPI SD reader, Ethernet PHY, dual UARTs. Most of what I'm looking at would be applicable with the z20x with an eZ80 CPU, but relatively little would apply to the other CPUs you might use.
Software wise, I've successfully built NuttX up to running NSH on it, mounting the SD card, with the RTC working. Here's the rough roadmap I have for NuttX building: - Check EMAC support works, up to DHCP and using ntpdate - Implement a syscall facility (via a RST, I think) - Write an ELF loader for the Z80 machine family (done except for relocations - but I can't fit a symbol table in Flash anyway) - Write a CP/M task, which also means supporting mixed memory mode - should only affect IRQ handling and task switching, I think There's still a number of integer size issues to work through first, I think. I am building with -Werror -Wconversion, which generates a huge number of errors. Most of them are harmless in practice, but ensuring I catch 24 bit issues means checking them all. An example is in sched/sched/sched_roundrobin.c: int decr; decr = MIN(tcb->timeslice, ticks); In this, tcb->timeslice is an int32_t, ticks is a uint32_t, and the MIN operation loses precision down to a 24-bit int. The round robin scheduler with default values should be fine with 24 or even 8 bits - I think you'd have to set ridiculous values to overflow anything. -- Byron On Sun, Feb 21, 2021 at 5:34 AM Brennan Ashton <bash...@brennanashton.com> wrote: > I saw that Greg had started initial support for this retro computer a > year ago and I was curious if anyone else has experience with it. I > was considering doing a board run and building one for myself and > would be happy to build a few if there are people interested since I > will have to order multiple PCBs anyway. > > https://z20x.computer/ > > Greg, are you still doing anything on this? I know you have had > interest in the past with it. > > It looks like there has been some renewed interest in the Z80 with > Byron integrating the clang port. > > --Brennan >
