Monday, 25 November 2013

ROM image for BASIC Level 3 with 24K on the Tototek SMS-PRO 32M flash cartridge

At the end of the previous post I mentioned that the Tototek SMS-PRO flash cartridge doesn't support bit 4 of memory location FFFCh in the 315-5235 mapper - that's the bit that enables 16K of RAM at $C000 - $FFFF once the Master System's 8K internal RAM has been disabled. Therefore, the best way to run BASIC Level 3 on the Tototek cartridge is to enable 16K of RAM at $8000 - $BFFF and leave the internal 8K of RAM enabled at $C000 - $DFFF. This is a ROM image that does exactly that. I have tested it on my Tototek cartridge and it runs BASIC Level 3 exactly the same as my home built ROM and RAM cartridge, with 18428 bytes free on the startup screen. The patch code is:

0000    3E08    LD A, 08h
0002    32FCFF    LD (FFFCh), A
0005    C30068    JP 6800h

instead of

0000    C30068    JP 6800h
0003    FF FF FF FF FF

This, combined with the export header, removal of the checksum jump and patch for 24K memory detect routine, allows BASIC Level 3 to run on the Master System using the Tototek cartridge.

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