🚀 go-pugleaf

In article <1989Dec14.0...@cs.rochester.edu> fu...@cs.rochester.edu (Mark Fulk) writes:
>If you haven't heard this one, you're probably wondering what it's about.
>On 6600's you loaded and stored X registers by loading A registers with
>the addresses; if you loaded A0, X0 got stored; if you loaded A1 to A4,
>the corresponding X got loaded.  To store an A register, you moved it to
>a free X register; to load it, you got the address into an X register.
>So X0 (I may have which registers did what a bit wrong; it's been ten years)
>mostly had to be kept empty.

Ok.  Here's the register scoop on a Cyber 170-state machine:  it has 24
registers.  8 B registers, 8 X registers, and 8 A registers.  The A and B
registers are address registers (B being called 'index' registers) and are
18 bits wide; X are data registers, and are 60 bites wide (one's complement,
yet...).  B0 is hardwired 0 (very useful, actually), and A0 is a "normal"
register.  A1-A5, however, are "load" registers, and A6,A7 are "store"
registers (loading, for example, 100 into A1 would cause X1 to be loaded
from location 100; loading 100 into A6 would cause X6 to be written into
location 100).

-- 
Sean Eric Fagan  | "Time has little to do with infinity and jelly donuts."
se...@sco.COM    |    -- Thomas Magnum (Tom Selleck), _Magnum, P.I._
(408) 458-1422   | Any opinions expressed are my own, not my employers'.