Yamaha V9938

Yamaha V9938 in an MSX2

The Yamaha V9938, also known as MSX-Video or VDP (Video Display Processor), ^[1] is a video display processor (VDP) used on the MSX2 home computer, ^{[2] [3]} as well as on the Geneve 9640 enhanced TI-99/4A clone, ^[4] and the Tatung Einstein 256. ^{[5] [6]} It was also used in a few MSX1 computers, in a configuration with 16kB VRAM. It was also used in the Zemmix V console. ^[7]

The Yamaha V9938 is the successor of the Texas Instruments TMS9918 used in the MSX1 and other systems. The V9938 was in turn succeeded by the Yamaha V9958.

Specifications

• Video RAM: 16–192 KB
• Text modes: 80 × 24, 40 × 24 and 32 × 24
• Resolution: 512 × 212 (16 colors from 512), 256 × 212 (16 colors from 512) and 256 × 212 (256 colors)
• Sprites: 32, 16 colors, max 8 per horizontal line
• Hardware acceleration for copy, line, fill and logical operations available
• Interlacing to double vertical resolution
• Vertical scroll register

Detailed specifications

• Video RAM: 4 possible configurations
  • 16 KB (modes G4 up to G7 will not be available)
  • 64 KB (modes G6 and G7 will not be available)
  • 128 KB: most common configuration
  • 192 KB, where 64 KB is extended-VRAM (only available as back-buffer for G4 and G5 modes)
• Clock: 21 MHz
• Video output frequency: 15 kHz
• Color encoding: Software switchable between 50 Hz and 60 Hz modes
• Sprites: 32, 16 colors (1 per line. 3, 7 or 15 colors/line by using the CC attribute), max 8 per horizontal line
• Hardware acceleration, with copy, line, fill etc. With or without logical operations.
• Vertical scroll register
• Capable of superimposition and digitization
• Support for connecting a lightpen and a mouse
• Resolution:
  • Horizontal: 256 or 512
  • Vertical: 192p, 212p, 384i or 424i
• Color modes:
  • Paletted RGB: 16 colors out of 512 (9-bit RGB)
  • Fixed RGB: 256 colors
• Screen modes
  • Text modes:
    • T1: 40 × 24 with 2 colors (out of 512)
    • T2: 80 × 24 with 4 colors (out of 512)
    • All text modes can have 26.5 rows as well.
  • Pattern modes
    • G1: 256 × 192 with 16 paletted colors and 1 table of 8×8 patterns
    • G2: 256 × 192 with 16 paletted colors and 3 tables of 8×8 patterns
    • G3: 256 × 192 with 16 paletted colors and 3 tables of 8×8 patterns
    • MC: 64 × 48 with 16 paletted colors and 8×2 patterns
    • All modes with 192 lines can have 212 lines as well (similarly 48 → 53 in MC)
  • Bitmap modes:
    • G4: 256 × 212 with 16 paletted colors
    • G5: 512 × 212 with 4 paletted colors
    • G6: 512 × 212 with 16 paletted colors
    • G7: 256 × 212 with 256 fixed-colors
    • All modes with 212 lines can have 192 lines as well (similarly 48 → 53 in MC)
    • All vertical resolutions can be doubled by interlacing

MSX-specific terminology

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

References

1. Yamaha V9938 MSX-Video Technical Data Book. ASCII CORP./NIPPON GAKKI CO., LTD. August 1985.
2. Center, MSX Resource (2023-04-02). "Yamaha V9938". MSX Wiki. Retrieved 2025-06-23.
3. Electronics. Vol. 58. McGraw-Hill. 1985. p. 19.
4. Reuter, Ron. "Geneve 9640". Mainbyte's Home of the Texas Instruments Computers. Retrieved 2023-08-23.
5. "Tatung Einstein 256". Computing History. Retrieved 2022-10-30.
6. "Tatung Einstein 256". Tatung Einstein Reborn!. Retrieved 2022-10-30.{{cite web}}: |first= missing |last= (help)
7. Packwood, Lewis (2024-01-25). Curious Video Game Machines. White Owl. p. 132. ISBN   978-1-3990-7378-3.

See also

• Texas Instruments TMS9918
• Yamaha V9958

External links

MSX-Video Technical Data Book, for Yamaha V9938 (August 1985) bitsavers.org

V9938 programmer guide http://rs.gr8bit.ru/Documentation/V9938-programmers-guide.pdf