29 May
2018
29 May
'18
4:32 a.m.
On 5/24/18, Arthur Krewat <krewat(a)kilonet.net> wrote:
* a DZ11 is UNIBUS and was only available on a KS10 - but I'd imagine
any straight serial port on a KA/KI/KL10 would do the same. If you were,
say, on a DCA mux, that had a 14.4K serial link straight into the
UNIBUS, there was much less of an effect.
DZ11s were available on PDP-11s and VAXen as well as the KS10.
Because the controller had no buffer it was dirt cheap. OK, perhaps,
for a realtime or lab application, but if you were doing timesharing
it could bring the CPU to its knees in short order. Some idiot
decided to use the same idea (no buffer in the controller) to reduce
the cost of the TU58 (aka DECtape II), Unlike the original DECtape,
which was extremely reliable, the TU58 was prone to frequent data
overrun and underrun errors even if you set things up such that it got
top scheduler priority.
-Paul W.