4 Aug
1997
4 Aug
'97
8:01 a.m.
There is what appears to be an RC clock composed of a
4.7 nF capacitor and
a multi-turn trimmer potentiometer in the upper left corner of the M7260
data path board in my 11/10. It looks like this clock feeds a 74197
counter, which has a 5-position rotary switch connected (presumably for
selecting what the incoming clock is divided by). I'll put a scope on pin
40 of the UART after I power the machine up to see what effect the rotary
switch has on the UART clock. It seems likely that the rotary switch is
used for making large changes in the baud rate and the trimmer is used for
tweaking.
If that's the board I think it is, it's an 11/10S. The preset was adjusted at
the factory, and you could set most standard baud rates using the switch. It
can't hurt to measure the frequency, of course.
I can check the printset next weekend for you if you can't figure it out.
--
Scott Ware s-ware(a)nwu.edu
-tony
6 Aug
6 Aug
3:51 a.m.
New subject: Consoles, Keys, and the PDP-11/10S
On Mon, 4 Aug 1997, PDP11 Hacker ..... wrote:
Scott Ware wrote:
>There is what appears to be an RC clock composed
of a 4.7 nF capacitor and
>a multi-turn trimmer potentiometer in the upper left corner of the M7260
>data path board in my 11/10. It looks like this clock feeds a 74197
>counter, which has a 5-position rotary switch connected (presumably for
>selecting what the incoming clock is divided by). I'll put a scope on pin
(snip)
If that's the board I think it is, it's an 11/10S. The preset was adjusted at
the factory, and you could set most standard baud rates using the switch. It
can't hurt to measure the frequency, of course.
I can check the printset next weekend for you if you can't figure it out.
I'll measure the UART clock frequency for each position of the rotary
switch after I fire up the 11/10 (hopefully this weekend). That should
give me all of the information that I need (for now...)
Other than the different CPU boards and the ability to function
as a "slave" processor to another PDP-11, how does the 11/10S differ from
a standard 11/10? My 11/10(S?) (10.5 inch box, single 16kW core plane,
most date codes in early '74) was configured as a standalone system when I
got it. Were the later 11/10 machines identical to the 11/10S, or did
DEC just produce an "improved" CPU board set for the 11/10S and use it in
the later 11/10 machines? Of course, I realize that it's possible that
some board swapping has taken place and neither is the case.
Thanks to everyone for the DEC key information. There isn't quite enough
of a key left in the 11/10 for a screwdriver to work. I'll probably pull
out the keyswitch and take it (and the key code for the 11/24 key) to a
locksmith sometime in the near future.
--
Scott Ware s-ware(a)nwu.edu
noon
New subject: Consoles, Keys, and the PDP-11/10S
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