PDP 11/73 is ALIVE!

From: der Mouse <mouse_at_Rodents.Montreal.QC.CA>
Date: Mon Nov 24 04:35:20 2003

>> [...], and the tape drive started to whir! It seeked back and forth
>> in tiny and equal increments. Then, the drive stopped and 012710
>> was displayed, then the _at_ prompt. I typed g, and got:
>> *** THIS VOLUME DOES NOT CONTAIN A HARDWARE BOOTABLE SYSTEM ***.
> OK, this means (a) the tape boot works, (b) the machine is basically
> OK, and (c) the tape connection is OK (now). Progress!

Yes! This is very encouraging.

> Since the "*** THIS VOLUME" ... comes from the boot loader (it is not
> in the bootstrap program...) on tape, we *did* load something from
> it.

Not quite. It comes from the boot loader obtained somehow from the
tape interface. We do not know whether the controller got it from ROM
on the controller, from ROM on the drive, or from stuff read off the
tape. My guess would be it's part of the code DMAed into low memory
(from ROM somewhere), not part of something read from the tape, simply
because it makes sense for there to be a complaint in case someone
tries to boot from a totally garbage tape, and this message looks very
much like what I'd expect that complaint to be.

> Even though we were able to load the secondary bootstrap off tape
> (which is blocks 0 and/or 1 on tape), we **ALSO** need to have that
> code know what we're loading from.

Yes...except that we don't actually know we loaded anything off the
tape (see above).

> Either the tape is a "ANSI standard" tape of some kind (with valid
> boot blocks, but no bootable system) or it is a regular bootable
> tape, but with a boot block for TM11 controllers...

Or it's a nonbootable tape, and the message came from the ROMed boot
code DMAed into low core.

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Received on Mon Nov 24 2003 - 04:35:20 GMT