LC8-P (M8365) PDP8 printer interface schematics

Charles Dickman chd at
Thu Jan 19 17:55:30 CST 2017

On Thu, Jan 19, 2017 at 1:18 PM, Marc Howard <cramcram at> wrote:
> Speaking of the LA-180 has anyone noticed the note in the PDP8A manual:
> "The General-Purpose Parallel I/O on the D etch revision
> of the M8316 module can be used as an interface for the
> LA 180. Data to the LA I80 must be supplied in com-
> plemented form. The IOTs are different from the LA8
> interface designed for the LA 180. A BC80-A cable, avail-
> able from DIGITAL, must be used to connect the General-
> Purpose Parallel I/O to the LA 180.
> Does OS8 know how to handle this way of interfacing a printer?

LPSV.PA has a compile time switch for LA180 and it includes a
complement before and after the character is written to the printer
buffer. I believe that some versions of SET have the capability of
modifying LPSV.BN to work with the LA180 at runtime. It is also
possible to use SET to modify the instructions directly.

Interestingly, the LPSV handler only contains two printer IOTs: one to
write the character and one to check the printer flag.


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