info-vax (06/29/82)
>From parker@NRL-CSS Tue Jun 29 14:32:09 1982
I installed a Versatec model 121 controller (C-PDP-11/DMA/18-BIT)
on my VMS 11/750. We are not trying to use the DMA; just using it
as a standard DEC line printer. I did remove the NPR jumper on the
backplane for the controller board per the versatec manual. VMS sees
the versatec as a line printer and is happy to print on it; and indeed
the versatec prints what it is told to. BUT, the 750 will not do anything
while the versatec is printing. It goes into a long pause.
My unibus contains (in order): the versatec, a DSD RX02 emulator, RK07,
LPA-11KK, and a Western TC-130 tape controller. Any ideas?info-vax (06/29/82)
>From mo@LBL-UNIX Tue Jun 29 16:24:59 1982
Confusus say: Interrupt-per-character interface in PIO-mode on FAST
peripheral mean CPU get shit kick out of it
servicing interrupts.
Answer: Modify driver to fill printer buffer before returning
from interrupt. Such fixes can cut overhead VERY
large amount; you might even get a cycle or two
at lower than IPL 15.info-vax (06/29/82)
>From chall@PARC-MAXC Tue Jun 29 16:53:03 1982
Versatec Model 121 controller is not byte-addressible. The standard DEC driver
does byte addressing. The Versatec VMS driver has fixed this problem.
Cliff Hall
Versatec
408 988-2801 X5215