FPGA Implementation of the Gigatron TTL Computer

IFPGA implementation of the Gigatron TTL microcomputer. The Gigatron is an 8-bit computer entirely made from classic 74-series logic ICs.The system can be connected to a VGA monitor, where it supports a resolution of 160 by 120 pixels at 64 colors. Furthermore, it features a four channel four bit audio synthesizer and is controlled by an NES-compatible game controller. Thus, the Gigatron functions as a full-blown 80s microcomputer that can be used to play video games.But instead of soldering all 38 chips and several diodes and resistors, I built one on a tiny piece of Silicon, an FPGA.The implementation was made for the Tang Nano 9K FPGA board. It includes an adapter board with voltage level converters that convert the 3.3 and 1.8V from the IO pins to the 5V TTL levels of the game controller and VGA monitor. It also includes the resistors for D/A conversion of sound and video as well as the connectors. A TV or monitor with HDMI can be directly plugged into the HDMI connector on the Tang Nano board.

The embedded flash of the Gowin GW1NR-9 FPGA on the Tang Nano board has only room for 38K command words, while the EPOROM of the TTL Gigatron has 64K. So I had to reduce the number of preinstalled programs from 12 to 8.

Here is a video about the Gigatron and its FPGA clone, if you want to know more.