40 and 80 column boards

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Introduction to 40 and 80 column boards for the VIC-20

The VIC-20 was popular but suffered stigma among "serious" computer users (i.e. programmers & researchers) because of its 22-column display, which they felt was too limiting. To remedy this several third party companies released display boards which plugged into the VIC-20's expansion port, thereby giving it the ability to display 40 or 80 columns of text at once.

VTE-40

  • Vendor: MSD, Inc.
  • Software: 4 KB terminal program (40 column screen)

MR 40/80

MC 6845

Video Pak Data 20

Includes 16K, needs extra power supply.

http://www.nemetzpower.de/Denial/Data20-16k.jpg

Display Manager Data 20 / Protecto 80 Cartridge

A VIC-20 setup equipped with a DATA-20 80-column display board. The VIC is outputting text to the 80-column monitor (right) and POKEing graphics to the 1702 colour monitor (left).

This cartridge takes over the video functions of the VIC, and allows the display of 40 or 80 columns B+W, using its own DIN port.

The VIC chip is still functional, so it is possible to setup a dual monitor system. Regular POKE statements can be used to update the original VIC chip screen.

This cartridge has space for expansion memory (U3-U6), which is populated in the Data-20 8K units.

Protecto80.jpg http://www.mainbyte.com/vic20/display_manager.jpg

Technical

Memory Map:

$9BF8 CRT Controller HD6845 / control register
$9BF9 CRT Controller HD6845 / data register
$9BFC Mode Register
     Bit 0: Character set. 0 - upper case, 1 - lower case
     Bit 5: 40/80 Columns. 0 - 40 Columns, 1 - 80 Columns
$A000-$A7FF BIOS ROM
     sys 40969 - 40 column mode
     sys 40972 - 80 column mode
     sys 40975 - return to vic 22 column screen
     sys 40978 - restart 40 or 80 column mode without clearing screen contents
$B800-$BFFF Video RAM

Function Keys:

F1 shift
F2 unshift
F3 Erase to end of line
F4 Erase to end of screen
F6 Screen dump
F8 Terminal mode

Links