On Wed, 2024-10-02 at 16:39 -0400, Paul Koning via cctalk wrote: > For the earlier 1311, lack of overlap made perfect sense. After all, > the 1620 has no interrupts, no parallelism of any kind: every I/O > operation stalls the CPU until the operation is finished. (That and > the BB instruction are among the reasons why Dijkstra rejected the > 1620.)
1401 had overlap, but as far as I can tell, only for cards and tape. The 1403 had a buffer, and 1401 had instructions to test whether the printer or carriage were busy, but that "overlap" didn't work the same as for cards and tape. I remember the 1620 being called CADET, but not because it was a beginner computer. It didn't have arithmetic hardware. It was done by table lookup. CADET meant "Can't Add, Doesn't Even Try." One of my colleagues exploited the table-based arithmetic to do octal arithmetic for satellite telemetry processing.
