Cat-644

This is a Simple 8-bit Computer using ATmega-644.

• features of this computer.
• processor: ATmel ATMega-644(20MHz)
• program memory: 64KB Flash
• Data memory: 4KB SRAM and 128KB additional SRAM
• Vedio: 64 color VGA(640×480), Actual resolution 256×240 or 512×240
• Sound: 8-bit PWM
• Storage: 1GB SD card
• Communications: RS-232, Ethernet(W5100)
• Input: PS/2 keyboard

the author wants to build 8-bit computer by himself. so, he makes it like below.

• Port A of Cat-644 is the enable line of another device.
• Port B is used by SPI bus when SD card or Ethernet working.
• Port C is used for JTAG but he doesn’t use. so it is just disabled.
• Port D is to generate analog signal and RS-232.

Schematics

(schematics link: https://github.com/carangil/cat644/blob/master/schematics/fullcomputer.png)

Main Components

• Atmel ATMega-644 20 Mhz 40-pin dip
• Hitachi H628128LP 128Kbyte SRAM 32-pin dip, 100ns or faster
• MAX232 RS-232 level converter
• Ethernet shield(W5100)
• SD card
• PS/2 Keyboard
• VGA monitor

More detailed Components: https://hackaday.io/project/2056/components

Source code

https://github.com/carangil/cat644

Source:  https://hackaday.io/project/2056-cat-644

Tags: 201408, avr, atmega-644, w5100, homebrew 8bit computer