John W Kennedy <email@example.com> wrote:
| I said "machine language" and I meant it. I haven't touched a 1401 since
| 1966, and haven't dealt with a 1401 emulator since 1968, but I can
| /still/ write a self-booting program.
Heh! I never dealt with a 1401 per se [except when running a 1410
in 1401 emulation mode to run the Autoplotter program, which wasn't
available for the 1410], but I still remember the IBM 1410 bootstrap
instructions you had to type in on the console to boot from magtape.
where the "v" accent is the "wordmark" indicator.
That says to read in a whole tape record in "load" mode (meaning
that wordmarks & groupmarks in memory are overwritten), synchronously
(stop & wait), from tape drive 0, starting at memory location
decimal 12, which, since the 1410 used *1*-based addressing,
was the location just after the no-op at location 11 above.
[Note that these are actual *machine* instructions, *not* "assember"!!
Like the 1401, the 1410 was a *character* machine, not an 8-bit-byte
binary machine. The bits in a character were named 1, 2, 4, 8, A, B,
and W (wordmark). Oh, and C, but that was character parity -- the
programmer couldn't set that separately.]
What was the corresponding 1401 boot sequence?
Oh, for the record, IMHO the DEC PDP-8 had a *much* simpler machine
language and assembler than the IBM 1401/1410. ;-}
Rob Warnock <firstname.lastname@example.org>
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