PDP 11/73 is ALIVE!

From: Fred N. van Kempen <waltje_at_pdp11.nl>
Date: Mon Nov 24 03:46:34 2003

On Sun, 23 Nov 2003, Ian Primus wrote:

> connectors were rotated 180 degrees. I swapped them, and typed in the
> program again. I the typed 2000g, 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 ***. It
> still didn't boot, but at least it's doing something! (Lesson for
> today, never connect hardware while tired, and always use a flashlight
> to see behind racks.)
OK, this means (a) the tape boot works, (b) the machine is basically
OK, and (c) the tape connection is OK (now). Progress!

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

Dunno which tape you are using, but: the address the boot loader uses
is that of the TM11/TS11. The instruction (100001) it sends to the
controller doesn't match that of the TM11, so it must be the TS11 it
thinks it has- and this is quite often the case with Emulex and Dilog
controllers.

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.

Suppose... we load the secondary boot. But: that thinks we're using a
TM11 controller. It then tries to load the rest off tape... but barfs,
because the TM11 doesnt respond (since it's really a TS11.) ... error..

> > It might be instructive to clear low memory first, then run the above
> > code, and see if low memory has changed.
I bet you'll find the above message in there, since that was loaded
to PC=0. 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...

> I might end up doing that, I can write down the output, and email it to
> you.
Use a terminal program on a PC or other system, and just log the
sessions. Much easier :)

> I have two blank tapes, as well as the SCSI nine track tape drive that
> goes with my Prime. I should be able to connect the other tape drive to
> a PC, and dd a tape image to a real tape. Is there a known working,
> bootable tape image out there on the 'net that I could use to test?
Sure, whatcha want? I can send you the Ultrix-11 mini root, which is
very small, and which will tell you whether things work or not..

Fred
-- 
Fred N. van Kempen, DEC (Digital Equipment Corporation) Collector/Archivist
Visit the VAXlab Project at                     http://www.pdp11.nl/VAXlab/
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Email: waltje_at_pdp11.nl         BUSSUM, THE NETHERLANDS / Sunnyvale, CA, USA
Received on Mon Nov 24 2003 - 03:46:34 GMT

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