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Description
The Yamaha V9958 is a Video Display Processor (VDP) used in MSX2+ and MSX turbo R computers. The V9958 is the successor of the Yamaha V9938 that was used in the MSX2. It is generally considered to be a minor upgrade of the V9938, with three YJK graphic modes (with up to 19,268 colors) and horizontal scrolling registers.
A few MSX2 computers have also this VDP, but the MSX2+ screen modes are not accessible in MSX-BASIC. See the list below.
Specifications
- VRAM: 128 KB + 64 KB of expanded VRAM
- Text modes: 80 x 24 and 32 x 24
- Resolution: 512 x 212 (16 colors out of 512) and 256 x 212 (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
On top of the Yamaha V9938 specifications, the V9958 added:
- Horizontal scrolling registers
- YJK graphic modes (similar to YUV) G6/G7 selection in these new modes affect only to command engine functionality.
- G6/G7 + YJK + YAE: 256 x 212, 12499 colors + 16 color palette
- G6/G7 + YJK: 256 x 212, 19268 colors
- Ability to execute hardware accelerated commands in non-bitmap screen modes
- Packaging: 64 pin "Shrink" DIP (SDIP) or in rare cases Ceramic DIP (CDIP)
MSX1 computers with MSX2+ VDP
A few MSX1 machines have the MSX2+ VDP (V9958). The MSX2/2+ screen modes are normally not accessible, as they require more than 16kB VRAM. These machines use the V9958 capacities for their Sega Mega Drive/Genesis part.
The V9958 is also present on the Brazilian MA-20 BR cartridge.
MSX2 computers with MSX2+ VDP
A few MSX2 machines have the MSX2+ VDP (V9958). The MSX2+ screen modes are not accessible in MSX-BASIC.
- Daewoo CPG-120
- Sakhr AX-370
- Victor HC-90 - V and T versions
- Victor HC-95 - V and T versions
MSX screen modes
On the MSX, the documented screen modes are often referred to by their assigned number in MSX-BASIC (see SCREEN and CALL KANJI pages for more info). 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 9 | G5 or G4 used in text mode | Korean 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 |
| Kanji0 | G4 or G6 used in text mode | MSX 2+ and tR |
| Kanji1 | G4 or G6 used in text mode | MSX 2+ and tR |
| Kanji2 | G4 or G6 used in text mode | MSX 2+ and tR |
| Kanji3 | G4 or G6 used in text mode | MSX 2+ and tR |