8 Feb
2012
8 Feb
'12
9:48 p.m.
On 2/8/12 9:25 PM, "Dave McGuire" <mcguire at neurotica.com> wrote:
On 02/07/2012 07:37 PM, allison wrote:
Yup. IOT instructions *are* instructions, no greater or lesser than any
other, and as you add IOT-based peripheral devices you are defining
semantics for previously undefined instructions. Very cool.
The biggest thing to watch for in PDP8 code is
recursion as you
need a software stack and handler to preserve data/addresses.
The DECmates had the 6120 and that implemented IOTs to create
a address and data stack( hardware can be built to do that in
any omnibus 8). The unique PDP-8 IO made doing things like that
more common than would be guessed.
Yeah, heck...plugging in a board can actually add instructions to the
instruction set! Great stuff.
-Dave