2 Oct
2007
2 Oct
'07
1:15 p.m.
On 2 Oct 2007 at 19:05, Tony Duell wrote:
And being a TMS9900-series CPU, aren't the
registers in external RAM? I
guess the subroutine stack is too.. Which doesn't leave much space for
anything else.
Yup, 32 bytes/16 words at a toss. And the usual subroutine linkage
used a BLWP (Branch and Link Workspace Pointer or "Bullwhip") which
set a completely new register frame for each subroutine. So that
didn't make for a lot of spare processor-local RAM. Using 256 bytes
of RAM at the late date of the 99/4A was screwy implmentation if
there ever was one, though I suppose that some can think of some kind
of advantage to this.
Cheers,
Chuck