The Yamaha V9938 is a Video Display Controller

Video Display Controller

A Video Display Controller or VDC is an integrated circuit which is the main component in a video signal generator, a device responsible for the production of a TV video signal in a computing or game system...

 (VDC) used in the Geneve 9640

Geneve 9640

-Geneve 9640:The Geneve 9640 is an enhanced TI-99/4A clone which was built by Myarc as a card to fit into the TI Peripheral Expansion System and used an IBM PC XT detached keyboard as well as a mouse. Released in 1987, it was in many ways similar to the earlier TI-99/8 which was in prototype form...

 enhanced TI-99/4A clone, as well as MSX

MSX

MSX was the name of a standardized home computer architecture in the 1980s conceived by Kazuhiko Nishi, then Vice-president at Microsoft Japan and Director at ASCII Corporation...

 80s

1980s

File:1980s decade montage.png|thumb|400px|From left, clockwise: The first Space Shuttle, Columbia, lifted off in 1981; American President Ronald Reagan and Soviet leader Mikhail Gorbachev eased tensions between the two superpowers, leading to the end of the Cold War; The Fall of the Berlin Wall in...

 home computers (more specifically, the MSX 2).

The Yamaha V9938, also known as MSX-Video or VDP (Video Display Processor), is the successor of the Texas Instruments TMS9918

Texas Instruments TMS9918

thumb|VDP TMS9918Athumb|VDP TMS9918Athumb|VDP TMS9928AThe TMS9918 is a Video Display Controller manufactured by Texas Instruments.-General information:...

 (used in the MSX1

MSX

MSX was the name of a standardized home computer architecture in the 1980s conceived by Kazuhiko Nishi, then Vice-president at Microsoft Japan and Director at ASCII Corporation...

 and various other systems). The V9938 was in turn succeeded by the Yamaha V9958

Yamaha V9958

The Yamaha V9958 is a Video Display Controller used in MSX 80s home computers. More specifically, the "TIM" upgrade to the TI-99/4A, MSX 2+ and MSX turbo R....

.

Specifications

• Video RAM: 64-128 KB
• Text modes: 80 x 24, 40 x 24 and 32 x 24
• Resolution
  Display resolution
  The display resolution of a digital television or display device is the number of distinct pixels in each dimension that can be displayed. It can be an ambiguous term especially as the displayed resolution is controlled by all different factors in cathode ray tube , flat panel or projection...
  
  : 512 x 212 (16 colours from 512), 256 x 212 (16 colours from 512) and 256 x 212 (256 colours)
• Sprite
  Sprite (computer graphics)
  In computer graphics, a sprite is a two-dimensional image or animation that is integrated into a larger scene...
  
  s: 32, 16 colours, max 8 per horizontal line
• Hardware acceleration
  Hardware acceleration
  In computing, Hardware acceleration is the use of computer hardware to perform some function faster than is possible in software running on the general-purpose CPU...
  
   for copy, line, fill, etc. Logical operations available
• Interlacing to double vertical resolution
• Vertical scroll register

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
  Clock rate
  The clock rate typically refers to the frequency that a CPU is running at.For example, a crystal oscillator frequency reference typically is synonymous with a fixed sinusoidal waveform, a clock rate is that frequency reference translated by electronic circuitry into a corresponding square wave...
  
  : 21 MHz
• Video output frequency: 15 kHz
• Sprites
  Sprite (computer graphics)
  In computer graphics, a sprite is a two-dimensional image or animation that is integrated into a larger scene...
  
  : 32, 16 colours (1 per line), max 8 per horizontal line
• Hardware acceleration
  Hardware acceleration
  In computing, Hardware acceleration is the use of computer hardware to perform some function faster than is possible in software running on the general-purpose CPU...
  
  , with copy, line, fill etc. With or without logical operations.
• Vertical scroll register
• Capable of superimposition and digitization
  Digitizing
  Digitizing or digitization is the representation of an object, image, sound, document or a signal by a discrete set of its points or samples. The result is called digital representation or, more specifically, a digital image, for the object, and digital form, for the signal...
  
  
• Support for connecting a lightpen and a mouse
  Mouse (computing)
  In computing, a mouse is a pointing device that functions by detecting two-dimensional motion relative to its supporting surface. Physically, a mouse consists of an object held under one of the user's hands, with one or more buttons...
  
  
• Resolution
  Display resolution
  The display resolution of a digital television or display device is the number of distinct pixels in each dimension that can be displayed. It can be an ambiguous term especially as the displayed resolution is controlled by all different factors in cathode ray tube , flat panel or projection...
  
  :
  • Horizontal: 256 or 512
  • Vertical: 192, 212, 384 (interlaced) or 424 (interlaced)
• Colour modes:
  • Paletted
    Palette (computing)
    In computer graphics, a palette is either a given, finite set of colors for the management of digital images , or a small on-screen graphical element for choosing from a limited set of choices, not necessarily colors .Depending on the context In computer graphics, a palette is either a given,...
    
     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 table of 8×8 patterns
    • G2: 256 × 192 with 16 paletted colours and 3 tables 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

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