[pdp7-unix] character table mysteries...

Phil Budne phil at ultimate.com
Tue Oct 22 13:20:36 AEST 2019

Could the missing "r" in the cas files be the one on p2 of 03-scope.pdf?

Is it possible all of the display character shapes were in one file?

How did the character tables get into memory?

maksys.s which writes an a.out to one of the tracks of the disk only
writes 3KW (3072 words), which is why I used that number in the
bootstrap paper tape.  Similarly, trysys.s only copies 3KW to the
bottom of memory.  So it doesn't seem like the top 1K of the lower 4K
(system memory) where that character table is supposed to live was
included in the "system".  Nor have I (yet) spotted any software that
seems to write to location 3072 (tho it wouldn't have to be very
large: an executable with the table, and a copy routine).  Now it was
core, and if undisturbed, it would just "be there" (much as I think
DDT was on the RLE PDP-1), and it could have been loaded from paper
tape using a "boot tape"


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