[cctalk] Re: IBM 360 and 1400 series emulation

On Apr 10, 2024, at 1:00 PM, CAREY SCHUG via cctalk &lt;cctalk(a)classiccmp.org&gt; wrote: I thought you could get regular channels as an optional feature? <pre>--Carey</pre> ... >>> >> ... 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 emulation 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