VGA stands for Video Graphics Array. It is a display hardware developed by IBM in 1987. It was first introduced with IBM PS/2 line of computers. It provides a resolution of 640×480 pixels and a refresh rate of 60 Hz.

VGA is referred as an array instead of an adopter because it was implemented from the start as a single chip (ASIC). It uses analog signals rather than digital signals.

Technical Specifications

The original VGA has the following specification:

  • 256 kB Video RAM
  • 16-color and 256-color paletted display modes.
  • 262,144-color global palette (6 bits, and therefore 64 possible levels, for each of the red, green, and blue channels via the RAMDAC)
  • Selectable 25.175 MHz or 28.322 MHz master pixel clock
  • Usual line rate fixed at 31.469 kHz
  • Maximum of 800 horizontal pixels
  • Maximum of 600 lines
  • Refresh rates at up to 70 Hz
  • Vertical blank interrupt
  • Planar mode: up to 16 colors (4-bit planes)
  • Packed-pixel mode: 256 colors (Mode 13h)
  • Hardware smooth scrolling support
  • No hardware sprites,
  • No Blitter, but supports very fast data transfers via “VGA latch” registers.
  • Barrel shifter
  • Split screen support
  • 0.7 V peak-to-peak
  • 75 ohm double-terminated impedance (18.7 mA, 13 mW)

Shape and Size

A VGA connector is shaped like a trapezoid and it has 15 pins. If you have a old monitor designed for the older standards may not be able to work with Video Graphics Array standards.

Compatibility

The older VGAs provide a resolution of 640×480 pixels. After that version, many revisions have been introduced. The most common version of VGA is Super VGA (SVGA). It allows for resolutions greater than 640×480, such as 800×600 or 1024×768.

VGA is referred as an array instead of an adopter because it was implemented from the start as a single chip (ASIC). It uses analog signals rather than digital signals.

Technical Specifications

The original VGA has the following specification:

  • 256 kB Video RAM
  • 16-color and 256-color paletted display modes.
  • 262,144-color global palette (6 bits, and therefore 64 possible levels, for each of the red, green, and blue channels via the RAMDAC)
  • Selectable 25.175 MHz or 28.322 MHz master pixel clock
  • Usual line rate fixed at 31.469 kHz
  • Maximum of 800 horizontal pixels
  • Maximum of 600 lines
  • Refresh rates at up to 70 Hz
  • Vertical blank interrupt
  • Planar mode: up to 16 colors (4-bit planes)
  • Packed-pixel mode: 256 colors (Mode 13h)
  • Hardware smooth scrolling support
  • No hardware sprites,
  • No Blitter, but supports very fast data transfers via “VGA latch” registers.
  • Barrel shifter
  • Split screen support
  • 0.7 V peak-to-peak
  • 75 ohm double-terminated impedance (18.7 mA, 13 mW)

Shape and Size

A VGA connector is shaped like a trapezoid and it has 15 pins. If you have a old monitor designed for the older standards may not be able to work with Video Graphics Array standards.

Compatibility

The older VGAs provide a resolution of 640×480 pixels. After that version, many revisions have been introduced. The most common version of VGA is Super VGA (SVGA). It allows for resolutions greater than 640×480, such as 800×600 or 1024×768.

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