[HECnet] DU11 vs. DUV11

[Lee Gleason]

              .IF DF   L$$SI1

              MOVB       @(R5)+,-(SP)       ;;; COPY CHARACTER FOR WORD MOVE
MOV         (SP)+,(R4)           ;;;   (SAVES 85 USECS ON PDT-11)

              .IFF       ; DF L$$SI1

              MOVB       @(R5)+,(R4)         ;;; OUTPUT A CHARACTER

              .ENDC     ; DF L$$SI1

OK, I'll bite.   Why is moving a character in the deferred location in
R5 to the stack and then, from the stack to the address in R4 faster
than just going from the deferred R5 location to the R4 address?
-- 

I'm even more curious what a PDT-11 optimization is doing in an RSX driver...was there at one time an RSX product product planned for the PDT family?

--
Lee K. Gleason N5ZMR
Control-G Consultants
lee.gleason at comcast.net