Yamaha V9938

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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 3 tables of 8×8 patterns
  - G2: 256 × 192 with 16 paletted colours and 1 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

[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