search

EtchedPixels / FUZIX

FuzixOS: Because Small Is Beautiful
Other
2.15k stars 271 forks source link

sc111: handle different SCM I/O base settings #956

Closed ra1fh closed 1 year ago

ra1fh commented 1 year ago

SCM < 1.3 did use I/O base 0x40. SCM 1.3 changed to 0xC0. Make sure to set the desired I/O base in both possible ICR register locations.

EtchedPixels commented 1 year ago

That's going to break if the kernel expects 0x40 as it stil seems to and when the loader writes to the serial.

Probably simpler just to require SCM 1.3 or higher, or ROMWBW, move to 0xC0 ?

ra1fh commented 1 year ago

The patch switches to the I/O base the kernel and the serial output functions expect. On my system this patch was required to make serial output work and boot Fuzix. I have SCM 1.3 (with 0xC0), and Fuzix running with default Z180_IO_BASE 0x40. I have tested with Z180_IO_BASE 0xC0 as well.

Requiring SCM 1.3 and changing Z180_IO_BASE to 0xC0 would certainly work as well. The release of SCM 1.3 happened fairly recently (Feb 2022) though. I don't know how many older systems with SCM < 1.3 are out there.

RomWBW has always been using I/O base 0xC0 on SC111. And the RomWBW loader for SC111 would do the I/O base switch if required before calling the kernel entry. So it does not have this problem.

ra1fh commented 1 year ago

Replaced by PR #965