10 Apr
2024
10 Apr
'24
4:47 p.m.
On Apr 10, 2024, at 11:25 AM, Jon Elson via cctalk
<cctalk(a)classiccmp.org> wrote:
On 4/10/24 07:18, CAREY SCHUG via cctalk wrote:
No channels? That doesn't sound right. The 360/44 I used certain had an RK05-like
drive in the CPU cabinet (I only remember one, though). I'm fairly sure it was a
16-sector pack, so more like an RK08. But the system ran both OS/360 and TSO, and had
three 2311 disk drives, three tape drives (with an amazingly ugly mechanical design), a
card reader/punch, and a line printer. Also some sort of terminal max, but I never used
the timesharing feature so I don't know what that involved.
It certainly had enough of a channel-like I/O system that the emulator program loader
could be implemented in a card reader channel program no different from that of other
360s. I remember quite well deciphering it using the CCW documentation on the "green
card".
Yes, the emuation of SS instructions was via traps, but specifically by a trap into
emulator mode in a separate chunk of memory not visible to the main OS.
I never saw the cartridge drive in use by anyone.
paul
Nearly all the 360s were microcoded, so adding a
bit more microcode let them emulate 1400/7000 series computers as a standard optional
feature. (well the model 44 emulated the 1620, and probably the 95/195 could not emulate
anything since they were hard wired).
The model 44 was not microcoded. It had faster floating point than a model /50
but no decimal or string instructions. Emulation of these was done through trap handlers.
I would assume any other machine emulators were done by something like an emulation
wrapper program - like Virtualbox or VMware. The model 44 had no channels, there was only
direct I/O (a set of 32-bit parallel input and output registers) and a pair of cartridge
hard drives inside the CPU cabinet. Think DEC RK05s.