Nibbler – Home Made CPU

 

Steve from the Big Mess o’ Wires blog has built a Home Made CPU called the Nibbler. Why the name? Because it is a 4 bit CPU (half of a byte is a nibble). Other than a creative name the project is quite an undertaking, it is built using 7400 logic all wire wrapped up for easy debugging. 🙂

“Some specs:

• 4 bit custom-made CPU
• 12 bit addressing, 4K address space size
• Harvard architecture – separate program and data memory spaces
• 2 MHz clock speed, 2 clocks per instruction = 1 million instructions/sec
• Thirteen 7400-series chips in the CPU data and control paths
• Two 28C16 EEPROMs store microcode for generating internal control signals
• 4K x 4 SRAM (CY7C168A)
• 28C64 EEPROM stores programs
• Four pushbutton inputs
• 16 x 2 character LCD
• Audio speaker
• About 100 mA current draw at 5V”