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thirty-two
@j.holmes.codes

I ended up doing some more research yesterday and ended up rewriting the core of my decoder/encoder to better handle low-level op codes. But, I'm starting to feel like I have a better handle on what these opcodes actually do, what they were intended to do, and how they are implemented

thirty-two@j.holmes.codes

oh yea! FUCK YEA, even! okay, now we are getting somewhere... The first image is with nothing initialized, the second is with a stolen payload from the original PIC.077 and the last one is filled with all the same value 0x01. HUGE!

thirty-two
@j.holmes.codes

So the opcodes in question are extended SCI0/SCI01 opcodes, and there are 5 of them: 0xFE02 : Set the mono specific dither palette mapping (the engine only seems to support pal 0) 0xFE03 : Draw to the mono buffer, using the pal lookup 0xFE04/06 : Stop drawing 0xFE05 : Draw to the mono, no lookup

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thirty-two
@j.holmes.codes

On engines that support these opcodes, mono PAL-0 is initialized to all zeros, and are solid black. The only game that seemingly has these specific mono opcodes is Colonel's Bequest, which does have the bytes to *attempt* to set palettes 1–3, but those seem to be ignored by the interpreter, afaict

thirty-two
@j.holmes.codes

The actual dithers are implemented in HERCMONO.DRV, of which there are many. And suprisingly enough, the HERCMONO.DRV that I have packaged with the demo of Colonel's Bequest is different than the one from the retail game. I need to pull my personal copy off the shelf and see which driver is included

thirty-two
@j.holmes.codes

Left are the 16 dither patterns of colonel's bequest demo, and right are the 16 dither patterns of the retail game (as far as I've been able to verify/research). I kinda like the demo ones better, tbh, but i'll probably implement both (or more if I find)

thirty-two
@j.holmes.codes

The dithers themselves appear to be 8x8 dithers, which would make sense. Though the latter versions definitely appear like they could be 4x4 dithers, maybe. Its also interesting that these are implemented on a totally separate buffer from the normal 16-color buffer channel, and exist simultaneously