25 Apr
2023
25 Apr
'23
6:47 a.m.
On Apr 25, 2023, at 9:37 AM, Rod Bartlett via cctalk
<cctalk(a)classiccmp.org> wrote:
Ken,
Core places being hand wired amazed me as well. The maintenance panels on the Honeywell
mainframes were hand wired as well. They were works of art with lots of toggle switches
and lights (the later models switched to LEDs). I could see most of the internal
registers using a fancy scroll wheel to select what register the lights should show. I
could also enter small diagnostic programs and single step through them using the panel.
Most of our core memories were 256K of 36 bit words (with a few spares for each
location). They took up lots of floor space. I suspect the fact that the power supplies
had to drive that much equipment was what made them sing.
The biggest core memories I remember are the ones in CDC mainframes "extended core
storage" -- at U of Illinois we had a 2 MW config, 60 bit words plus parity.
Actually, ECS was organized as 488 bit words, with 6 µs access time, 8 way interleaved,
for a transfer rate of 10 MW per second (matching central memory). Nice.
That was an odd structure, it was described as "linear select" which I think
means an address line per word rather than the usual X/Y concident current selection
scheme. Pictures show a rectangular memory array; perhaps it was 488 bits high by some
number (512?) wide but I haven't been able to find the details.
paul