Last modified on 9 October 2013, at 07:40

No$cart

Revision as of 07:40, 9 October 2013 by Arnoldemu (Talk | contribs) (Technical)

A utility by Nocash which converts a disk image to a cartridge.

http://nocash.emubase.de/

The tool hasn't been tested on the GX4000 so cartridges that are created may not work on it. You should test this to be sure.

In addition if the game/program has any of the following it will not work on GX4000:

  • It uses keyboard or requires keyboard input to get into the game
  • It uses 128K ONLY (or it's a bad "crack" that requires 128K to work even though the game itself would work in 64K).

However, the tool is easy for the non-programmer to use.

Technical

The created cartridge image has the OS, BASIC and Amsdos embedded in it and the data from the disk image (tracks/sectors).

Page 0 is OS.
Page 1 is BASIC.
Page 2 contains part of the disk image data.
Page 3 contains AMSDOS.
Page 4 onwards contains disk image data.

The OS, BASIC and AMSDOS are based on CPC6128 ROMs and have all been patched.

BASIC patches

BASIC has been patched in the following way:

  • Offset &33 has been set to 0. It is the first character of " BASIC 1.1" text.

This stops the BASIC ROM from printing this text.

  • Offset &D7 has been set to 0. It is the first character of "Ready" text. This stops the BASIC ROM from printing this text.
  • At offset &af9, the code has been changed from:
LD HL,&ac8a

to

CALL &d583
  • Part of the text "Random number seed ?" at offset &1583 (&D583 in the CPU address space) has been patched with the following code:
ld hl,&ac8a
ld a,&aa
cp (hl)
ret nz
pop af
ld (hl),' '
scf
ret