23 Jan
2020
23 Jan
'20
12:42 a.m.
From: Warner Losh
this predates everything except Whirlwind which I
can't find a paper for.
Given the 'Whirlwind is a ringer' comment, I asssume this:
https://en.wikipedia.org/wiki/Whirlwind_I<
is what they mean.
Pretty interesting machine, if you study its instruction set, BTW; with no
stack, subroutines are 'interesting'.
Noel
25 Jan
25 Jan
12:57 a.m.
New subject: Unix quix
On 1/22/20, Noel Chiappa <jnc(a)mercury.lcs.mit.edu> wrote:
Pretty interesting machine, if you study its instruction set, BTW; with no
stack, subroutines are 'interesting'.
The IBM S/360/370 operating systems such as DOS/360 and DOS/VS didn't
use a stack, either, unless you were doing recursion. When we got our
VAX, I was puzzled as to why they would throw away an entire register
just to point at a stack.
-Paul W.
30 Jan
30 Jan
10 a.m.
New subject: Unix quix
On Wed, 22 Jan 2020, Noel Chiappa wrote:
[ Whirlwind ]
Pretty interesting machine, if you study its
instruction set, BTW; with
no stack, subroutines are 'interesting'.
Not much worse than the PDP-8 :-) Plant return address in first word and
jump to the second word; to return, do an indirect jump to the first word.
Recursion was possible. but I think you had to emulate the stack.
-- Dave
12:32 p.m.
New subject: Unix quix
On 30/01/20, Dave Horsfall wrote:
On Wed, 22 Jan 2020, Noel Chiappa wrote:
[ Whirlwind ]
On the whirlwind the sp (subprogram) instruction puts the return address
in the A register. with ta (transfer A) you can put it into the address
part of an instruction, so a function call is as simple as
...
sp foo
...
foo: ta foo0
...
foo0: sp .
So it's pretty nice you can use sp for calls and jumps. cp (conditional
sp) works the same but only jumps if AC is negative.
The big difference between the WW and later machines is that there is no
indirection on the WW! You end up writing lots of addresses into
instructions. It's even weirder on the TX-0 with its (original) limited
instruction set where you don't even have instructions to just store an
address, only the full word.
aap
Pretty interesting machine, if you study its
instruction set, BTW; with
no stack, subroutines are 'interesting'.
Not much worse than the PDP-8 :-) Plant return address in first word and
jump to the second word; to return, do an indirect jump to the first word.
Recursion was possible. but I think you had to emulate the stack.
1787
days inactive
1795
days old
3 comments
4 participants
participants (4)
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Angelo Papenhoff -
Dave Horsfall -
jnc＠mercury.lcs.mit.edu -
Paul Winalski