> On Apr 10, 2024, at 11:25 AM, Jon Elson via cctalk <cctalk@classiccmp.org>
> wrote:
>
> On 4/10/24 07:18, CAREY SCHUG via cctalk wrote:
>> 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.
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
