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Rapid Plot

Posted: Tue Jul 22, 2014 9:57 pm
by GCHarder
;Low resolution graphics in M/L
;In the page 111 of the book linked below
;has a very fast LM routine for PLOT/UNPLOT:
;http://www.zx81.megahospedagem.com.br/f ... os/ulm.zip
;The book is in Portuguese language, but the
;routine is ready for use.
;Before call it, set the registers B and C with X and Y,
;respectively, and set register A with $40 for
;PLOT, or with $00 for UNPLOT.

This is supposed to be a fast PLOT replacement routine.

Personally, I don't see much difference. That may be because of the overhead required to set up a PLOT command from BASIC, before the USR call. It might work a lot better from within a purely MC application, bypassing any ROM PLOT/UNPLOT calls. I've included a couple of demos.

One caution, be aware that the routine is self-modifying using a LD (PLOT+1),A, where (PLOT+1) is an address located WITHIN the routine . So be careful if you use it and move it to a different address.

Regards;

Greg

Re: Rapid Plot

Posted: Thu Jul 24, 2014 8:47 pm
by GCHarder
FYI, by changing the instruction LD A,15 to LD A,17 it is possible to PLOT on the lower 2 lines of the display. The overall resolution is then 64x48, which makes this PLOT replacement actually more useful.

I'm attaching this mod with demo.

Regards;

Greg

Re: Rapid Plot

Posted: Fri Jan 05, 2018 9:50 pm
by Shaun_B
Thanks, this could be what I need before I delve in to high resolution.

Regards,

Shaun.