[Amforth] Useful additions to the "Extended VM"

[Martin N. <amf...@mg...>]

It's a handy way of using the A & B variables as local variables when
needed.

    .dw $ff03
    .db "a>r"
    .dw VE_HEAD
    .set VE_HEAD = VE_ATOR
XT_ATOR:
    .dw PFA_ATOR
PFA_ATOR:
      push ah
      push al
    jmp_ DO_NEXT

    .dw $ff03
    .db "r>a"
    .dw VE_HEAD
    .set VE_HEAD = VE_AFROMR
XT_AFROMR:
    .dw PFA_AFROMR
PFA_AFROMR:
      pop al
      pop ah
    jmp_ DO_NEXT


Quick and simple definitions which allow you to do stuff like this:
: workwitha
	a>r
		use a with impunity
	r>a
;

I've translated these from my own version, so I hope it's survived.

--
Regards,

Martin Nicholas.

E-mail: rep...@mg... (Address will be valid throughout 2021).