Yamaha V9958
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The Yamaha V9958 is a Video Display Processor (VDP) used in MSX 80s home computers. More specifically, the MSX2+, MSX turbo R and the "TIM" upgrade to the TI-99/4A.
The Yamaha V9958, also known as MSX-Video, is the successor of the Yamaha V9938. It was clearly conceived not to be a very major upgrade to its predecessor, which hampered its adoption. The main new features are three graphical YJK modes (with up to 19268 colours) and horizontal scrolling registers.
Specifications
- Video RAM: 128 KB + 64 KB of expanded VRAM
- Text modes: 80 x 24 and 32 x 24
- Resolution: 512 x 212 (4 or 16 colors out of 512) and 256 x 212 (16, 256, 12499 or 19268 colors)
- Sprites: 32, 16 colors, max 8 per horizontal line
- Hardware acceleration for copy, line, fill, etc.
- Interlacing to double vertical resolution
- Horizontal and vertical scroll registers
Detailed specifications
For detailed specifications, please refer to the Yamaha V9938 page, with the following changes:
- Horizontal scrolling registers
- YJK graphics modes (similar to YUV)
- G7 + YJK + YAE: 256 x 212, 12499 colors + 16 color palette
- G7 + YJK: 256 x 212, 19268 colors
- Ability to execute hardware accelerated commands in non-bitmap screen modes
- Lightpen and mouse functions from V9938 were removed
- Composite video output function from V9938 was removed
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 |
| Screen 10 | G7 with YJK and YAE | MSX 2+ and tR |
| Screen 11 | G7 with YJK and YAE | MSX 2+ and tR |
| Screen 12 | G7 with YJK | MSX 2+ and tR |