Subj : Re: Favourite sound chip?
To   : Retroswim
From : dflorey
Date : Thu Apr 10 2025 07:40 pm

 Re> From the PC side, you can access on the MD side:
 Re> - All RAM
 Re> - All VDP registers (incl VRAM and CRAM)
 Re> - Yamaha OPN FM chip
 Re> - Ti PSG chip
 Re> - Z80 memory and registers
 Re> - Joystick ports
 Re> 
 Re> You cannot access the cartridge slot or the TMSS (lockout chip) ROM.
 Re> 
 Re> From the MD side, you can access on the PC side:
 Re> - All RAM
 Re> - All ROMs (e.g. system BIOS, VGA BIOS, and any option ROMs)
 Re> - All IO space (e.g. serial/parallel ports, VGA registers, interval
 Re> timer, any ISA cards not requiring DMA or interrupts like AdLib or POST
 Re> analyser cards)
 Re> 
 Re> You cannot use BIOS routines, as the CPU is halted, so no DMA or
 Re> anything that relies on interrupts.
 Re> 
 Re>  D> I'll need to watch the video sometime... Tomorrow maybe!
 Re> 
 Re> Let me know how you go!
 Re> 
 Re> As of right now, there are exactly *TWO* packages that make use of the 
 Re> TeraDrive's capabilities. Puzzle Construction Set, a demo included with
 Re> the system showing off what can be done. And "The Manhole", an adventure
 Re> game by Cyan (of MYST fame), published by Activision, which uses a
 Re> special driver to access the Yamaha OPN FM chip.
 Re> 
 Re> And I guess my demo makes three! :D
 Re> 
 Re> Unfortunately there is a specific setup routine needed to unlock the MD 
 Re> hardware from the PC side, and bespoke ways of accessing it, so you
 Re> can't use any old game with, say, AdLib support.
 Re> 
 Re> Hope this answers your questions!

That is really cool. I guess it makes sense that the PC CPU is halted - I did
wonder about that. Was such an experimental time... 

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