UPD7220 Video Card (Revision 2)

The uPD7220 Video Card revision 2 is a video card with 128KB of VRAM using the uPD7220 GDC or its variants. It operates at a maximum clock speed of 32Mhz. The card is based on the original uPD7220 card I (Dylan Brophy) made, which had half the VRAM and generally was far simpler. This card solves several issues with the older card, at the cost of greater size and complexity.

Detailed Specifications

• 16-color VGA output
• 128KB of RAM
  • 4 RAM chips, 32KB each, 25ns access and write time
  • 16 bit bus (8 bits per chip, two chips per byte)
  • 4 color bits per pixel, 4 pixels per word in RAM
    • Maximum 262144 pixels (hardware double buffering disabled)
      • Suggested resolutions: 544x480, 640x408
    • Maximum 131072 pixels (hardware double buffering enabled)
      • Suggested resolutions: 448x288, 400x300
• uPD7220 at up to 24Mhz, Z7220 at up to 32Mhz
• uPD7220 wide mode supported
  • Allows higher pixel clock frequencies, for higher resolutions and lower visible display times
  • Accesses two VRAM words per uPD7220 clock cycle
• Direct access to VRAM is provided to the host CPU