Yamaha V9938
The Yamaha V9938 is a video display processor used on the MSX2 home computer, as well as on the Geneve 9640 enhanced TI-99/4A clone. It was also used in a few MSX1 computers, in a configuration with 16kB VRAM.
The Yamaha V9938, also known as MSX-Video or VDP, is the successor of the Texas Instruments TMS9918. 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, 256 × 212 and 256 × 212
- 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
- * 64 kB
- * 128 kB: most common configuration
- * 192 kB, where 64 kB is extended-VRAM
- Clock: 21 MHz
- Video output frequency: 15 kHz
- Sprites: 32, 16 colors, 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
- * Fixed RGB: 256 colors
- Screen modes
- * Text modes:
- ** T1: 40 × 24 with 2 colors
- ** T2: 80 × 24 with 4 colors
- ** 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
- * 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
- ** All vertical resolutions can be doubled by interlacing
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 | T1 | MSX 1 |
| Screen 0 | 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 |
