thumb|right|300px|Yamaha V9938 in an [[MSX2]]
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 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:
{| class="wikitable" border="1" width=50%
!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
|}