22 Jun
2016
22 Jun
'16
7:26 p.m.
On Wed, Jun 22, 2016 at 7:45 PM, Swift Griggs <swiftgriggs at gmail.com> wrote:
It's just pointer arithmetic to add a signed integer to a character
pointer, to move the pointer forward or backward some number of
character positions.
Of course, it can be used on anything represented in a PDP-10 byte,
which can be any number of bits up to 36; it doesn't have to be a
character per se, but character handling is possibly the most common
use of the PDP-10 byte instructions.
People who
complain about twos-compliment being a weird hack
Encode negative integers using this one weird trick!
By the way, it's two's complement. A twos compliment would be
something like, "Hey, nice twos!". #overlypedantic :-)
ADJBP (ADJust
Byte Pointer, which can back up as well as move forward).
I find that weird, but
possibly useful once I figured out how to implement
it.