[tvrfan]

To any long time experts out there -

Do you know if the multibanks do a checksum or not ?

Does it do one for each bank ?

The checksum obvious for single banks like A9L, but I'm looking at BWAK3N2 (which appears to use the secondary stack R22 as the background task pointer?) and I can't see how or where it does any checksum. SAD doesn't work much at all for BWAK3N2 so I need to add more functionality, which doesn't help....

Any help or info on this appreciated - thanks

[sailorbob]

The multiple bank checksum calculation is the same as single bank checksum with each bank being added in turn. In the BWAK3 strategy the routine is at 0x872D9.

[tvrfan]

Thanks Bob, will check that out....

[2 mins later ]

Damn, I should have spotted that....Now you pointed that out, it's quite obvious.
Interesting that the routine stops at a slightly different end address for each bank....

[sailorbob]

No point in checksumming unused areas of ROM and, IIRC, the VID block is excluded.