Text-based VGA Display for RC2014

VGARC is a text-based VGA display for RC2014. It is based on 8K of dual port RAM to communicate between RC2014 and video display.

Note: This page describes VGARC rev0.1 and prior prototype version. VGARC rev0.1 is now obsolete, replaced with VGARC rev1

• 8K bytes of dual port RAM to simplify communication between Z80 and video display logic
• State machine in Altera EPM7128S CPLD generates the video timings
• 8×8 pixel font
• Font lookup table resides in the dual port RAM and is user programmable
• Display 56 lines, 80 characters per line

Schematic

PC board gerber photoplots

EPM7128SQC100 CPLD equations

TinyType Font, 8×8 font table

Conway Game of Life demonstration, Glider Gun on 56 x 80 screen

56 lines and 80 column text explaining the features of VGARC

This section describes the modification to VGARC rev0.1 to add a PS2 keyboard.

CPLD equation for VGARC with PS2 keyboard

Engineering change for adding PS2 keyboard

Test software

This prototype is based on RC2014 Rev 2 Prototype board which already has a EPM7128SQC100 connected to RC2014 bus with a number of user programmable test points. A 4Kx8 dual port RAM, IDT 71342, is breadboarded in the prototype area and connected to the EPM7128S. The CPLD outputs drive a HD15 connector's red and blue signals as well as the horizontal and vertical syncs.

• 4K x 8 dual port RAM, IDT71342
• State machine in EPM7128SQC100 generates video timing
• 640 x 480 display area, only 640 X 192 contains data due to RAM size limitation
• 8×8 pixel font
• 1K x 8 font table resides in the dual port RAM, user programmable

Schematic

EPM7128SQC100 CPLD equations

Conway's game of life