> On Aug 3, 2025, at 12:41 PM, bput <[email protected]> wrote: > > Even more confusing, CP/M v2.2H on > my Kaypro does this without any special configuration; if I switch to a > User area that has no files in it, the Kaypro will happily execute a > program from User area 0 with no special action required. I'm thinking > vendor modifications are in play here.
The mystery goes on: my Kaypro does this as well and I went into RunCPM[1], which lets you pick from several CCPs and provides a BDOS that reads and writes to the host filesystem. Jerry's right in that DR's 2.2 CCP doesn't do this. ZCPR 2 doesn't even support USERs at all (wow!). ZCPR 3 seems to have the concept of USERs but the USER command doesn't work. I'm not familiar with Z-system enough to say if that's expected but the Z-System in general was a 2.2 replacement but I believe the command syntax is different enough that I'm not doing things right. CCPZ, which is a community-made CCP for 2.2, doesn't. Z80CCP (which I believe the DEC Rainbow used, at least there's a carve-out in the DEC BIOS for it) does, as does both the 8080 version. I'm not completely clear if this is a 3.0-ish system. I didn't test RunCPM's internal CCP implementation since it's platform-specific to a modern emulator. In general, the farther something is from DR's system, the more likely it is to treat USER 0 as a kind of $PATH. But clearly Kaypro, at least, added the ability. Bone-stock 2.2 doesn't have this ability at all. [1] RunCPM is this: https://github.com/MockbaTheBorg/RunCPM
