VGA3 successor to the CVDU

The VGA3 ,as the name suggests, is an alphanumeric board which operates at VGA frequencies, making it usable on a far larger number of monitors that the CVDU, which it replaces. The core of the board is the HD6445CP4 (PLCC) CRTC, which is capable of operating at character frequencies up to 4.5mhz. The VGA3 uses 9-bit wide characters with a dot frequency of 28.322mhz (VGA standard), or a character rate of about 3.15mhz. A standard VGA screen 80 character columns wide and 25 character lines refreshes at a rate of 70hz. An alternate format, 80 character

The board uses a single memory chip to hold both the display memory