I was working a patch and noticed these two similar cmds strings.

I was doing this and needed the result in D.
Fdiv ; result in X

So I tried
LDD 0,x. Which take the same cycle time as below.
But it didn't work. Not sure why.

PSHX
PULA
PULB
Did work,
Any help would be appreciated.

 

The LDD 0,X is using the value in X as the address to retrieve the data from. X is being used as an index register which has the 0 portion of the arguments added to it for the final address.

RBob.

 

I'll chalk that up to lack of sleep.....
honest..

edit:
ok

So LDD 0,x is

LoaD accD (which is acc A & B combined) with the value stored at the location pointed to by Address register X with "0" offset added to the address.

PSHX is put data at the location pointed to by Address register X
on the stack pointer LSB first.

PULA is pull data from stack pointer into accA. (MSB)
PULB is pull data from stack pointer into accB. (LSB)

Got so used to doing the math on a calculator and ignoring the ADDRESS part that it tripped me up when I had to think that way.

 

OK on the first one (LDD 0,X). Not OK on the second one (PSHX). The PSHX puts the value that is IN X onto the stack, LSB first.

RBob.

 

Plenty of things to trip over in this dark room I insist on exploring.