Yamaha V9938
From Wikipedia, the free encyclopedia
The Yamaha V9938 was a Video Display Processor (VDP) used in the Geneve 9640 enhanced TI-99/4A clone, as well as MSX 80s home computers (more specifically, the MSX 2).
The Yamaha V9938, also known as MSX-Video, is the successor of the Texas Instruments TMS9918 (used in the MSX1). The V9938 was in turn succeeded by the Yamaha V9958.
[edit] Specifications
- Video RAM: 64 KB to 128 KB
- Text modes: 80 x 24, 40 x 24 and 32 x 24
- Resolution: 512 x 212 (16 colours from 512) and 256 x 212 (256 colours)
- Sprites: 32, 16 colours, max 8 per horizontal line
- Hardware acceleration for copy, line, fill, etc. Logical operations available.
- Interlacing to double vertical resolution
- Vertical scroll register
[edit] Detailed specifications
- Video RAM: 128 kB
- Optionally 64 kB, in which case screen modes G6 and G7 are not available
- Optionally 192 kB, where 64 kB is extended-VRAM (only available as backbuffer for G4 and G5 modes)
- Clock: 21MHz
- Video output frequency: 15kHz
- Sprites: 32, 16 colours (1 per line), 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
- Resolution:
- Horizontal: 256 or 512
- Vertical: 192, 212, 384 (interlaced) or 424 (interlaced)
- Colour modes:
- Paletted RGB: 16 colours out of 512
- Fixed RGB: 256 colours
- Screen modes
- Text modes:
- T1: 40 × 24 with 2 colours (out of 512)
- T2: 80 × 24 with 4 colours (out of 512)
- All text modes can have 26.5 rows as well.
- Pattern modes
- G1: 256 × 192 with 16 paletted colours and 1 tables of 8×8 patterns
- G2: 256 × 192 with 16 paletted colours and 3 table of 8×8 patterns
- G3: 256 × 192 with 16 paletted colours and 3 tables of 8×8 patterns
- MC: 64 × 48 with 16 paletted colours 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 colours
- G5: 512 × 212 with 4 paletted colours
- G6: 512 × 212 with 16 paletted colours
- G7: 256 × 212 with 256 fixed-colours
- All modes with 212 lines can have 192 lines as well (similarly 48 → 53 in MC).
- All vertical resolutions can be doubled by interlacing
- Text modes:
[edit] 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 |
