This is primarily about VDP from the Sega Master System game console and video chip from the MSX 2 series computers. Specifically about Yamaha YM2602 (aka Sega 315‑5124) and Yamaha V9938 respectively. Deep analysis of chip architecture, instruction set, bus and memory configuration (including on-chip linear buffers from sprite engine), chips floor-plan...

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    For the floor plan: visual6502.org lists the TMS9918 as "status 2" (sample acquired, analysis not started). So if anyone wants to work on it ...
    – dirkt
    Nov 22, 2018 at 14:50
  • I think only the 9938 branch of the family has anything like an instruction set, through its command engine.
    – Tommy
    Nov 22, 2018 at 14:58

1 Answer 1


If don't know if anyone has done a "comparative analysis" of the evolution of the 9918A, but here is generally a lot of forum discussion about what was added to later derivatives of the 9918A, i.e. the 9938/58, 9990, NES and Sega chips, etc.

The visual6502 group has had a 9918A for a long time (I have sent them a few myself), and I have been eagerly waiting for them to decap the device so some die-level analysis can be done.

However, a lot of what is inside the chips can be derived from the datasheets and external interfaces, and proven via emulation, HDL modeling (FPGA cores), and software (i.e. using the VDP). Plus, some of the designers (Karl Guttag for example) have given interviews, released unpublished details, and answered architecture questions via email in the past, so there is at least a lot of comprehensive information available about the original 9918A.

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