PDP-11 M873 ROM card info?

Noel Chiappa jnc at mercury.lcs.mit.edu
Wed Mar 30 07:24:20 CDT 2016

    > Does anyone have a -YB we can dump?

Can I repeat my plea for this? (And also a -YC?)

    > I have a -YA, and will dump that in a few moments

OK, I'm mostly done with the disassembly; available here:


I haven't fully understood the TA11 code (and don't plan to), nor the
DECtape/magtape code (might get to that some day), but the disk and paper
tape code is completely done. (I'm currently loading over serial lines, for
getting the machines running, etc.) The paper tape code is 'interesting'; it
took me a while to figure out _exactly_ how it worked.

It appears (to me, at least) that that code will not function correctly
unless the abs-loader has at least one byte of '0' pad on the end of it, for
two reasons. (See the comments on the listing.) Luckily, my copy of the abs
loader binary has such; although real .LDA tapes have blank leader, of
course, the .LDA files I'm generating don't.

The serial line code in the M9301 (-YA at least, and probably the others too)
uses the identical code, so it has the identical issue.


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