World’s Worst Video Card

July 17, 2022

This is my second Ben Eater project. In this video series, Ben talks about how VGA signals work and walks us through building a circuit that provides the correct timing of sync signals so that a monitor recognizes the signal and displays an image stored on an EEPROM.

completed_build
Here is the completed build in all its glory!

Parts List

 
Description Quantity
Breadboard 5
22 AWG Solid Tinned-Copper Hook-Up Wire
10MHz full can crystal oscillator 1
680Ω resistor 3
1.5kΩ resistor 3
74LS00 (Quad NAND gate) 3
74LS04 (Hex inverter) 4
74LS30 (8-input NAND gate) 8
74LS161 (4-bit synchronous binary counter) 6
28C256-15 EEPROM 1
DE15 Female VGA breakout connector 1

You will also need a monitor with VGA input, an EEPROM programmer like the  XGecu TL866II Plus, an oscilloscope and a function generator.

This video card displays an image of 100 x 75 pixels with 64 (indexed) colors. 

Schematics

HSync Circuit, Image Credit: Ben Eater
VSync Circuit, Image Credit: Ben Eater
HSync and VSync circuits are connected to an EEPROM which drives a simple resistor DAC (digital-to-analog converter) to generate an image. Image Credit: Ben Eater
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