2 layers229.9 × 93.3 mm
2 layers229.9 × 83.8 mm
Smaller card
ethanjamesauto/modular_8bit_computer2- Size
- 229.9 × 83.8 mm
- Copper layers
- 2
- Thickness
- 1.6 mm
- Parts
- 33
- Nets
- 63
- Pads
- 132
- Tracks, vias
- 0, 0
- Pours
- 1
- Routed
- Not yet
- KiCad
- KiCad 8.0 (file 20240108)
- Created
- 18 Aug 2024
- Updated
- 8 Nov 2025
Overview
Smaller card is an open-source printed circuit board by ethanjamesauto, from the ethanjamesauto/modular_8bit_computer repository on GitHub. It is a 2-layer board of 229.9 × 83.8 mm with 33 parts on 63 nets.
It is built around the 74LS245SC. Its parts include 12 resistors, 12 diodes, 5 connectors, 2 capacitors and 1 IC.
Main components
1README
README.mdModular 8-bit Computer
This is the repository for an 8-bit computer system that is built using cards with a standardized interface.
- CPU card
- Protoboard card
- This card contains an onboard clock generator, address and data registers/buffers, and a protoboard area for testing designs.
- Bus interface modeling
Here's an example of a card:
Current Bus Specification
// The main bus wires (32+8=40 wires total)
// On the bus connector, all buses have LSBs closer to the power pins and MSBs farther away
wire VCC_5V;
wire GND;
wire clk; // generated by motherboard clock generator
wire rst_n; // probably a button on the motherboard
wire VCC_3V3;
wire we_n; // active LOW
wire oe_n; // active LOW
wire int_n; // pulled up by motherboard; driven down by any peripheral (could be used for interrupts)
wire [7:0] data;
wire [15:0] addr; // 64k address space is suppored by default. More address bits may be added later
wire [7:0] aux_bus;Parts
33| Qty | Value | Footprint | References |
|---|---|---|---|
| 12 | 470 | Resistor_SMD:R_0603_1608Metric_Pad0.98x0.95mm_HandSolder | r0, r1, r3, r4, r45, r46, r47, r48, r49, r50, r51, r52 |
| 2 | C | Capacitor_SMD:C_1206_3216Metric | C1, C2 |
| 2 | Conn_01x01_Pin | Connector_PinHeader_2.54mm:PinHeader_1x01_P2.54mm_Vertical | J33, J34 |
| 2 | Conn_01x08_Pin | Connector_PinHeader_2.54mm:PinHeader_1x08_P2.54mm_Vertical | J5, J15 |
| 1 | 1 | Resistor_SMD:R_1206_3216Metric | 5V_rsns1 |
| 1 | 3V3_RAW | LED_SMD:LED_0603_1608Metric_Pad1.05x0.95mm_HandSolder | D5 |
| 1 | 5V | LED_SMD:LED_0603_1608Metric_Pad1.05x0.95mm_HandSolder | D2 |
| 1 | 5V_RAW | LED_SMD:LED_0603_1608Metric_Pad1.05x0.95mm_HandSolder | D1 |
| 1 | 74LS245 | Package_DIP:DIP-20_W7.62mm_Socket | U1 |
| 1 | Conn_01x40_Pin | Connector_PinHeader_2.54mm:PinHeader_1x40_P2.54mm_Horizontal | J1 |
| 1 | Do0 | LED_SMD:LED_0603_1608Metric_Pad1.05x0.95mm_HandSolder | D30 |
| 1 | Do1 | LED_SMD:LED_0603_1608Metric_Pad1.05x0.95mm_HandSolder | D31 |
| 1 | Do2 | LED_SMD:LED_0603_1608Metric_Pad1.05x0.95mm_HandSolder | D32 |
| 1 | Do3 | LED_SMD:LED_0603_1608Metric_Pad1.05x0.95mm_HandSolder | D33 |
| 1 | Do4 | LED_SMD:LED_0603_1608Metric_Pad1.05x0.95mm_HandSolder | D34 |
| 1 | Do5 | LED_SMD:LED_0603_1608Metric_Pad1.05x0.95mm_HandSolder | D35 |
| 1 | Do6 | LED_SMD:LED_0603_1608Metric_Pad1.05x0.95mm_HandSolder | D36 |
| 1 | Do7 | LED_SMD:LED_0603_1608Metric_Pad1.05x0.95mm_HandSolder | D37 |
| 1 | RESET | LED_SMD:LED_0603_1608Metric_Pad1.05x0.95mm_HandSolder | D4 |
More from ethanjamesauto/modular_8bit_computer
12- 2 layers229.9 × 83.8 mm
- 2 layers229.9 × 93.3 mm
- 2 layers229.9 × 83.8 mm
- 2 layers222.3 × 127 mm
- 2 layers86.4 × 53.8 mm
- 2 layers229.9 × 86.4 mm
- 2 layers2.8 × 6.6 mm
- 2 layers111.8 × 77.2 mm
- 2 layers48.3 × 48.3 mm
- 2 layers119.4 × 45.7 mm
- 2 layers104.1 × 50.8 mm
Similar boards
- 2 layers231.1 × 106.7 mm
- 2 layers365.8 × 254 mm
Raemixx500
SukkoPera/Raemixx500
Open Hardware Remake of the Commodore Amiga 500+ Mainboard
372 parts316 - 2 layers125 × 98 mm
3-in-1
mudmin/AnotherMaker
This is where I will store code snippets for AnotherMaker Videos
44 parts258 - 2 layers182.9 × 172.7 mm
- 2 layers365.1 × 203.2 mm
DIAG
Nakazoto/CenturionComputer
This is just a simple backup of all the files related to the Centurion that I have stored on my HD. The Wiki itself has far more in-depth information about the Centurion and it's individual cards.
150 parts172 - 2 layers135.3 × 106.7 mm
- 2 layers370.8 × 298.5 mm
8 Bit Computer
The-Invent0r/8-bit-Computer-PCB
These are the KiCAD files for my 8-Bit Computer.
323 parts142 - 2 layers89.5 × 77.5 mm
Apple2-IO RPi
tjboldt/Apple2-IO-RPi
Apple II expansion card using a Raspberry Pi for I/O
24 parts140MIT
Questions
How big is the Smaller card PCB?
It measures 229.9 × 83.8 mm and has 2 copper layers, 1.6 mm thick.
What parts does the Smaller card use?
33 parts, built around the 74LS245SC. 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 Smaller card KiCad files?
From the ethanjamesauto/modular_8bit_computer repository on GitHub, at the commit this page was made from: the board is base_card_for_verilog_kicad/smaller_card/smaller_card.kicad_pcb. PCBKit opens the board in the browser, with nothing to install.
Can I use the Smaller card design in my own project?
Its repository states no licence, so its author keeps all rights: ask ethanjamesauto before reusing the design.