7 Feb
2022
7 Feb
'22
11:40 p.m.
On 2022-02-07 21:41, Dennis Boone wrote:
I don't agree. Skips aren't really any more strange than branches. We're
talking assembler here anyway. There are bound to be jumps all over the
place always. Not really more spagetti in any architecture compared to
any other.
The probably more "ugly" thing in the PDP-8 is that you do self
modifying code very often.
With the limited instruction set of the PDP-8, only one accumlator, and
very limited addressing modes, combining any instruction with an ISZ
(increment, basically) of that instruction allowed it to walk over some
memory space easily, since the address is in the low 7 bits of the
instruction.
Johnny
--
Johnny Billquist || "I'm on a bus
|| on a psychedelic trip
email: bqt(a)softjar.se || Reading murder books
pdp is alive! || tryin' to stay hip" - B. Idol
PDP-8 works
this way too. Many people wrinkle their noses about it,
but I find the skip model to be very convenient and easy to wrangle.
The Honeywell x16 family does this too. It's more or less
definitionally spaghetti code, which is probably the cause of the nose
wrinkling. It'd be interesting to see if the rise in awareness of some
of this sort of "structured code" thinking coincides with a decline in
architectures using skips.