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Yamaha V9958

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Yamaha V9958
Yamaha V9958 in ceramic package

The Yamaha V9958[1][2][3] is a Video Display Processor used in the MSX2+[4] and MSX turbo R series of home computers, as the successor to the Yamaha V9938 used in the MSX2. The main new features are three graphical YJK[5][6][7] modes with up to 19268 colors and horizontal scrolling registers. The V9958 was not as widely adopted as the V9938.

Specifications

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  • Video RAM: 128 KB + 64 KB of expanded VRAM
  • Text modes: 80 × 24 and 32 × 24
  • Resolution: 512 × 212 (4 or 16 colors out of 512) and 256 × 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

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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 × 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

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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

References

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  1. ^ IC Master. United Technical Publications. 2001.
  2. ^ Martín Sesma, Sergio (2016-10-03). Arqueología informática: los ordenadores MSX en los inicios de la microinformática doméstica (Proyecto/Trabajo fin de carrera/grado thesis). Universitat Politècnica de València.
  3. ^ Redazione (2008-10-20). "MSX - Vari Costruttori- 1983". CyberLudus.com (in Italian). Retrieved 2022-11-13.
  4. ^ Alex, Wulms (1995). "Schermen op MSX - De 2+ schermen" (PDF). MSX Computer & Club Magazine (72).
  5. ^ MSX Licensing Corporation (2022). "The YJK screen modes". MSX Assembly Page.
  6. ^ Niemietz, Ricardo Cancho (2014). Issues on YJK colour model implemented in Yamaha V9958 VDP chip (PDF).
  7. ^ "VCFe Vortrag vom 2016.04.30 - Homecomputer und Spielkonsolen - Videoarchitekturen als visuelles Medium". neil.franklin.ch. Retrieved 2022-11-13.