27 Jul
2010
27 Jul
'10
2:43 p.m.
On 27 Jul 2010 at 21:42, Tony Duell wrote:
T(5000) appears to translate to 2C 13 88, followed by a D3... Since I
don't know the register architecture of the FST-1/2, I can't say for
certain where the value goes. My guess is a register--not required,
but possible.
--Chuck
It doesn;t have to be a CALL in the normal sense (i.e.
it stacks the
PC contents, it might just save the PC in some other register (or in
the word preceeding the subroutine itself, or..)
I meant it in that sense--i.e., the value of the current PC is saved
(on a stack, in memory or in a register) and is program-accessible
(not all CPUs allow this) and a transfer of control occurs. It's
only people born since 1970 who think that all machines have hardware
stacks. Consider it to be equivalent to a TSX, RJ or BAL instruction
if you desire. (The first time I heard someone referring to S/360
BAL, I thought "Boy, that's pretty silly, limiting yourself to one
instruction.").
to access the
inline data and then resumes after the end of the
string has been reached.
Similarly, 2C xx xx appears to be a load immediate of some sort, as
it's used to set up constant data before a D3 xx xx instruction.
How do you know it's immediate, rather than, say, absolute. And how do
you know it's a load and not some other opeation between a register
and the next 2 bytes?