floobydust wrote:
DOS/65 - yes, this is Richard's version of CP/M for the 6502. Having looked at David's source for CPM/65, my view is that David has taken the CP/M 2.2 source code and directly ported it to the 6502. Richard's DOS/65 provides a functional equivalent of CP/M but does not appear to have been a direct port routine by routine. All of the BDOS functions exist in PEM and all of the CCP functions exist in CCM, but they are not written the same way. Code size is fairly equivalent however.
I'd be interested in hearing more details about CPM65, including any comparisons to DOS/65. Since DOS/65 is very CP/M-like, it's probably reasonable to talk about DOS/65 a bit in this thread, if David has no objections.
I'm not sure it's totally on-topic for this forum, but I was reading the CPM65 commits and the storage of the CP/M filesystem on top of the CBM DOS filesystem caught my attention. I dealt with this on the SoftBox (
webpage,
disassemblies), which is a CP/M add-on for the Commodore PET/CBM computers. It also stores CP/M sectors directly in CBM DOS sectors, where one 256-byte CBM DOS sector contains two 128-byte CP/M sectors. I found
this explanation of how DOS/65 does it. Another CP/M add-on for PET, the
Z-RAM, uses REL files as CPM65 initially did.