PDP-11/84 (KDJ11-B) and Error 61

Jerome H. Fine jhfinedp3k at compsys.to
Tue Feb 2 19:28:31 CST 2016


 >Ulrich Tagge wrote:Hi Glen,

> [Snip]
>
> List/change parameters in the Setup table
>
>     A - ANSI Video terminal (1)          0=No,   1=Yes  = 1
>     B - Power up  0=Dialog, (1)=Automatic, 2=ODT, 3=24  = 1
>     C - Restart   0=Dialog, (1)=Automatic, 2=ODT, 3=24  = 1
>     D - Ignore battery                   0=No,   1=Yes  = 0
>     E - PMG 0-(7) 1=.4us, 2=.8, 3=1.6, 4=3.2,...7=25.6  = 7
>     F - Disable clock CSR                0=No,   1=Yes  = 0
>     G - Force clock interrupts           0=No,   1=Yes  = 0
>     H - Clock  0=Power supply, 1=50Hz, 2=60Hz, 3=800Hz  = 1

Does anyone have an idea as to how the choice of the 800Hz
option was made?

I could understand 1000Hz or perhaps 1200Hz which allows
division by both 50 and 60.  But 800Hz seems like such an
unlikely value.

On the other hand, on the PRO350, the clock rate was 64Hz
and every 16 ticks, I assume that one tick was discarded so
as to support the appearance of a 60 Hz clock.

Jerome Fine


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