4 layers82.7 × 41.5 mm
4 layers62.6 × 31.6 mm
Program Counter
georgesleen/8-BitComputerRepo to track my 8-bit computer progress
- Size
- 62.6 × 31.6 mm
- Copper layers
- 4
- Thickness
- 1.6 mm
- Parts
- 27
- Nets
- 35
- Pads
- 111
- Tracks, vias
- 238, 4
- Pours
- 2
- Routed
- Yes
- KiCad
- KiCad 8.0 (file 20240108)
- Created
- 14 Jun 2024
- Updated
- 17 Sep 2025
Overview
Program Counter is an open-source printed circuit board by georgesleen, from the georgesleen/8-BitComputer repository on GitHub. It is a 4-layer board of 62.6 × 31.6 mm with 27 parts on 35 nets, routed with 238 tracks and 4 vias.
It is built around the 74LS245SC and 74LS161DC. Its parts include 10 resistors, 8 diodes, 3 ICs, 3 connectors and 2 capacitors. It belongs with the retro computing and games boards of this library.
Main components
274LS245SC
-0℃~+70℃ 12ns@5V,45pF 15mA 24mA 4.75V~5.25V 74LS 8 Bidirectional Output enable Schmitt trigger Tri-State - Buffers, Drivers, Receivers, Transceivers ROHSTexas InstrumentsBuffers, Drivers, Receivers, Transceivers
74LS161DC
-0℃~+70℃ 14ns 32MHz 4 4.75V~5.25V 74LS 93mW Asynchronous Binary Counter Programmable divide ratio、Reset function、Cascade counter、Synchronous counting Rising Edge Synchronous - Counters, DividersTexas InstrumentsCounters, Dividers
README
README.mdCustom 8-Bit Computer
Repository showcasing a simple 8 bit computer built around the 7400 series ICs.
Heavily inspired by Ben Eater's 8-Bit computer series on youtube, with additional support from Digital Computer Electronics by Albert Paul Malvino
Parts
27| Qty | Value | Footprint | References |
|---|---|---|---|
| 8 | 220 | Resistor_SMD:R_1206_3216Metric_Pad1.30x1.75mm_HandSolder | R1, R2, R3, R4, R5, R6, R7, R8 |
| 8 | ~ | LED_SMD:LED_1206_3216Metric_Pad1.42x1.75mm_HandSolder | D1, D2, D3, D4, D5, D6, D7, D8 |
| 2 | 0.1uF | Capacitor_SMD:C_1206_3216Metric_Pad1.33x1.80mm_HandSolder | C1, C2 |
| 2 | 74LS161 | Package_DIP:DIP-16_W7.62mm_Socket_LongPads | U1, U2 |
| 1 | 10k | Resistor_SMD:R_1206_3216Metric_Pad1.30x1.75mm_HandSolder | R10 |
| 1 | 1k | Resistor_SMD:R_1206_3216Metric_Pad1.30x1.75mm_HandSolder | R9 |
| 1 | 2N3904 | Package_TO_SOT_THT:TO-92_Inline | Q1 |
| 1 | 74LS245 | Package_DIP:DIP-20_W7.62mm_Socket_LongPads | U3 |
| 1 | Bus | Connector_Molex:Molex_PicoBlade_53048-0810_1x08_P1.25mm_Horizontal | J1 |
| 1 | Control | Connector_Molex:Molex_PicoBlade_53048-0410_1x04_P1.25mm_Horizontal | J3 |
| 1 | Power | Connector_Molex:Molex_PicoBlade_53048-0410_1x04_P1.25mm_Horizontal | J2 |
Questions
How big is the Program Counter PCB?
It measures 62.6 × 31.6 mm and has 4 copper layers, 1.6 mm thick.
What parts does the Program Counter use?
27 parts, built around the 74LS245SC and 74LS161DC. The full list of its parts is on this page, with links to each part's symbol and footprint where PCBKit's library has them.
Where can I download the Program Counter KiCad files?
From the georgesleen/8-BitComputer repository on GitHub, at the commit this page was made from: the board is Schematics/Program Counter/Program Counter.kicad_pcb and its schematic Schematics/ALU/ALU V1.kicad_sch. PCBKit opens the board in the browser, with nothing to install.
Can I use the Program Counter design in my own project?
Its repository states no licence, so its author keeps all rights: ask georgesleen before reusing the design.
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