A bug fixed, high score load/save finalised, and not much else.

As usual not a lot of progress over the weekend due to Real Life.

jotd did find another bug that I'd never actually noticed before; on the attract mode gameplay screen the ground objects were misaligned with respect to the map - how I missed that I have no idea! 😮

Upon closer inspection I noticed that it was the map that was offset (not the objects) and only after the title screen - not after the high score table screen. This made it easy to compare the values of the inputs to the map-rendering routine in each case, since the attract mode always plays Area 1 from the start. And it was only a handful of minutes before the difference was revealed and less than a minute later that the culprit was found.

Nothing even remotely interesting - just an unintialised register used as the index into the table that specifies the offset in the map data for each area. The Z80 code was clearing A to initialise a few other variables, and then using that as the index. In the transcode I was using the CLR instruction instead, then using an uninitialised D0 as the index.

Since this code is not time-critical at all, I reverted to clearing and then using D0 as per the Z80 code, keeper it closer to the original source.

The only other update was finalising the high score load/save on the Neo Geo. The only system to use BRAM (as BRAM) is the MVS; the other two systems (AES/NGCD) support memory card I/O, even though the AES implements a "virtual" memory card in BRAM. I decided to first read from BRAM on MVS systems, and then attempt to read from memory card (on all systems), overwriting any BRAM data if found. On saving high scores, MVS systems write to BRAM, and then all systems attempt to write to memory card.

Probably not how it's supposed to be done, but that's my preference.

Since the "known" list of bugs had grown by 2 (from 8 to 10), and I have fixed one of those, the outstanding list now stands at 4 (with 1 still yet to be confirmed as an actual bug). But for the week heading forward, I'll be spending my lunchtimes at work trying to finish the audit of the MAIN ROM.