Rapid Plot

Anything Sinclair ZX Basic related; history, development, tips - differences between BASIC on the ZX80 and ZX81
Post Reply
User avatar
GCHarder
Posts: 178
Joined: Sat Dec 14, 2013 6:46 pm

Rapid Plot

Post by GCHarder » Tue Jul 22, 2014 9:57 pm

;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
Attachments
Rapid Plot.zip
Program, scans & demos
(720.55 KiB) Downloaded 73 times

User avatar
GCHarder
Posts: 178
Joined: Sat Dec 14, 2013 6:46 pm

Re: Rapid Plot

Post by GCHarder » Thu Jul 24, 2014 8:47 pm

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
Attachments
Screen.jpg
Screen shot
Screen.jpg (2.27 KiB) Viewed 562 times
Rapid Plot (64x48).zip
64x48 PLOT routine
(2.35 KiB) Downloaded 39 times

Shaun_B
Posts: 377
Joined: Wed Apr 22, 2009 9:22 am

Re: Rapid Plot

Post by Shaun_B » Fri Jan 05, 2018 9:50 pm

Thanks, this could be what I need before I delve in to high resolution.

Regards,

Shaun.

Post Reply

Who is online

Users browsing this forum: No registered users and 1 guest