# Eater 8-bit computer

From Christoph's Personal Wiki

The **Eater 8-bit computer** (aka the **SAP-1** {**S**imple **A**s **P**ossible} version 1) is a breadboard computer created by Ben Eater. I have decided to make my own version of the computer and will be providing information on its progress in this article.

## Computer modules

- Clock module
- Registers
- Arithmetic logic unit (ALU)
- Random access memory (RAM) module
- Program counter
- Output register
- Bringing it all together
- CPU control logic

## Complete parts list

- 14 x Breadboard
- 1 x 22 AWG Solid Tinned-Copper Hook-Up Wire
- 10 x 1kΩ resistor
- 9 x 10kΩ resistor
- 1 x 100kΩ resistor
- 24 x 470Ω resistor
- 1 x 1MΩ resistor
- 1 x 1MΩ potentiometer
- 6 x 0.01µF capacitor
- 16 x 0.1µF capacitor
- 1 x 1µF capacitor
- 4 x 555 timer IC
- 2 x 74LS00 (Quad NAND gate)
- 1 x 74LS02 (Quad NOR gate)
- 5 x 74LS04 (Hex inverter)
- 3 x 74LS08 (Quad AND gate)
- 1 x 74LS32 (Quad OR gate)
- 1 x 74LS107 (Dual JK flip-flop) Note: The videos use the 74LS76 which is extremely difficult to find. The 74LS107 is functionally equivalent but be careful, it has a different pinout.
- 2 x 74LS86 (Quad XOR gate)
- 1 x 74LS138 (3-to-8 line decoder)
- 1 x 74LS139 (Dual 2-line to 4-line decoder)
- 4 x 74LS157 (Quad 2-to-1 line data selector)
- 2 x 74LS161 (4-bit synchronous binary counter)
- 8 x 74LS173 (4-bit D-type register)
- 2 x 74189 (64-bit random access memory)
- 6 x 74LS245 (Octal bus transceiver)
- 1 x 74LS273 (Octal D flip-flop)
- 2 x 74LS283 (4-bit binary full adder)
- 3 x 28C16 EEPROM
- 3 x Double-throw toggle switch
- 3 x Momentary 6mm tact switch
- 1 x 8-position DIP switch
- 1 x 4-position DIP switch
- 44 x Red LED
- 8 x Yellow LED
- 12 x Green LED
- 21 x Blue LED
- 4 x Common cathode 7-segment display

## External links

- Build an 8-bit computer from scratch — by Ben Eater