Text-based VGA Display for RC2014

Introduction

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.

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Features

  • 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

Theory of Operation

Design Information

Schematic

PC board gerber photoplots

EPM7128SQC100 CPLD equations

Software

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

Adding PS2 Keyboard

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

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CPLD equation for VGARC with PS2 keyboard

Engineering change for adding PS2 keyboard

Test software



VGARC Prototype

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.

www.retrobrewcomputers.org_lib_plugins_ckgedit_fckeditor_userfiles_image_builderpages_plasmo_vgarc_dsc_47901015.jpg

www.retrobrewcomputers.org_lib_plugins_ckgedit_fckeditor_userfiles_image_builderpages_plasmo_vgarc_dsc_47911015.jpg

Features

  • 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

Theory of Operation

Design Information

Schematic

EPM7128SQC100 CPLD equations

Software

Conway's game of life

builderpages/plasmo/vgarc.txt · Last modified: 2020/11/29 21:19 by plasmo
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