Source Codes

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Revision as of 08:36, 9 January 2013 by Arnoldemu (Talk | contribs) (General Notes)

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This article contains source codes and programming examples. You may also have a look at




CPC Plus


File access

Floppy disk




Other routines


Cross Development

General Notes

  • Memory range for programs is &0040-&a700. This avoids firmware and memory allocated by AMSDOS disc ROM.
  • Basic programs start at &170.
  • Firmware uses interrupt mode 1 of the Z80 (interrupts jump to &0038)
  • Lowest place you can *LOAD* a binary file to with BASIC is &389 e.g.:
memory <address>-1
load "code",<address>
call <exec>
  • Screen is normally at &c000-&ffff. (It can be changed using firmware, or using CRTC R12/R13)
  • Stack is normally at &c000 and goes down.
  • Extra registers (BC', AF', HL', DE' are reserved by the firmware). Avoid if you are using firmware functions.
  • Lower rom (containing OS) can be paged into memory between &0000-&3fff.
  • Upper rom is selectable, examples are BASIC and AMSDOS. They can be paged into memory between &c000-&ffff.
  • From basic, a game is run with:

keep it in the safe memory ranges and it'll run from cassette and disc.

  • Screen is normally 40 crtc chars wide (CRTC R1=40), 25 crtc chars tall (CRTC R6=25). 8 scan lines per char (R9=7). Firmware functions assume this.
  • Screen is bitmapped. You must draw/erase your own sprites and text.