The Yamaha V9938, also known as MSX-Video or VDP (Video Display Processor), is a video display processor (VDP) used on the MSX2 home computer, as well as on the Geneve 9640 enhanced TI-99/4A clone, and the Tatung Einstein 256. It was also used in a few MSX1 computers, in a configuration with 16kB VRAM. It was also used in the Zemmix Super V console.
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 (3-3-2 bit RGB) 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 systemScreen 0 (width 40) T1 MSX 1Screen 0 (width 80) T2 MSX 2Screen 1 G1 MSX 1Screen 2 G2 MSX 1Screen 3 MC MSX 1Screen 4 G3 MSX 2Screen 5 G4 MSX 2Screen 6 G5 MSX 2Screen 7 G6 MSX 2Screen 8 G7 MSX 2 Note: Screen 9 was reserved for South Korean MSX2 units.
References
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