Yamaha V9958

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Yamaha V9958
Yamaha V9958 in ceramic package

The Yamaha V9958 is a Video Display Processor used in the MSX2+ and MSX turbo R series of home computers and the "TIM" upgrade to the TI-99/4A. Also known as the MSX-Video chip,[citation needed] it is the successor to the Yamaha V9938. The main new features are three graphical YJK modes with up to 19268 colours and horizontal scrolling registers. The V9958 was not as widely adopted as the V9938.

Specifications[edit]

  • Video RAM: 128 KB + 64 KB of expanded VRAM
  • Text modes: 80 x 24 and 32 x 24
  • Resolution: 512 x 212 (4 or 16 colors out of 512) and 256 x 212 (16, 256, 12499 or 19268 colors)
  • Sprites: 32, 16 colors, max 8 per horizontal line
  • Hardware acceleration for copy, line, fill, etc.
  • Interlacing to double vertical resolution
  • Horizontal and vertical scroll registers

Feature changes from the V9938[edit]

The following features were added to or removed from the Yamaha V9938 specifications:

  • Added horizontal scrolling registers
  • Added YJK graphics modes (similar to YUV)
    • G7 + YJK + YAE: 256 x 212, 12499 colors + 16 color palette
    • G7 + YJK: 256 x 212, 19268 colors
  • Added the ability to execute hardware accelerated commands in non-bitmap screen modes
  • Removed lightpen and mouse functions
  • Removed composite video output function

MSX-specific terminology[edit]

On MSX, the screen modes are often referred to by their assigned number in MSX-Basic. This mapping is as follows:

Basic mode VDP mode MSX system
Screen 0 (width 40) T1 MSX 1
Screen 0 (width 80) T2 MSX 2
Screen 1 G1 MSX 1
Screen 2 G2 MSX 1
Screen 3 MC MSX 1
Screen 4 G3 MSX 2
Screen 5 G4 MSX 2
Screen 6 G5 MSX 2
Screen 7 G6 MSX 2
Screen 8 G7 MSX 2
Screen 10 G7 with YJK and YAE MSX 2+ and tR
Screen 11 G7 with YJK and YAE MSX 2+ and tR
Screen 12 G7 with YJK MSX 2+ and tR