Unknown DEC indicator panel

Jon Elson elson at pico-systems.com
Wed Nov 2 20:20:04 CDT 2016

On 11/02/2016 12:10 PM, Brian L. Stuart wrote:
> On Tue, 11/1/16, Jon Elson <elson at pico-systems.com> wrote:
>>    Also, some IBM  publications (where I'm more
>> familiar with their models) had  some photos
>> of machines that probably were in-house
>> prototypes that were quite different than the
>> production  version.
> Along the same lines, the picture in the original PDP-8
> manual was of a machine that had a front panel that
> looked more like the PDP-5 panel than the one shipped
> on the 8s.  Given how close the machines were in
> architecture, it wouldn't be surprising for a prototype.
> As it turns out, I saw the picture in the manual a few
> years before I ever saw a real straight-8.  To this day,
> the real straight-8s look a little "wrong" to me.
Yup, in fact, I think you could turn a PDP-5 into a PDP-8 
with about 25 boards
(one tray of system building blocks) and some wire.  Mostly, 
add an electronic
instruction counter register and alter the instruction fetch 
logic to stop accessing
location zero.  That's the only difference visible to the 
programmer, I think.


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