[Simh] PDP-6 Microtape bootstrap

[Lars Brinkhoff]

Lars Brinkhoff wrote:
> Lars Brinkhoff wrote:
>> Below is the PDP-6 Microtape (DECtape) bootstrap code used at the MIT
>> AI Lab.  There are some of us wondering why it was written this way?
> Has anyone imaged any MIT DECtapes?

Thanks to Peter Samson and Al Kossow, we got some MIT DECtape images.

They didn't have any suitable boot blocks, but in a deleted block there
was this source code:

https://github.com/PDP-10/its-vault/blob/master/system-tape-generator

The HACK macro takes input words and writes them as two halfword
instruction and a SETZM.  All which have the high bit set as needed by
the loader.  Also, they are subtracted with 1.