Main logic
About the Main logic PCB
Main logic is an open source PCB design by tmarhguy, published on GitHub under the MIT license. It is a 2-layer board measuring 98.5 × 95.5 mm, with 122 components from 7 distinct parts.
Other key parts include the 74HC157 and 74HC86. By type, the board carries 96 transistors, 20 ICs, 4 capacitors and 2 connectors.
From the project
8-bit combinational ALU built from scratch with 3,488 CMOS transistors (KiCad + SPICE + Logisim + 1.24M tests
Individual PCB boards for the 8-Bit Transistor ALU system
This directory contains KiCad projects for each functional board in the ALU system.
Note: The ALU can be implemented as: - Monolithic: Single 270×270mm board (alu/) - Modular: Separate boards (mainlogic/, addsub/, flags/, main_control/)
Current implementation uses modular approach for easier assembly and debugging.
Main components on the Main logic
Main logic bill of materials (BOM)
122 components, 7 distinct parts.
| Qty | Part | Footprint | Refs |
|---|---|---|---|
| 16 | 74HC157 | SOIC-16_3.9x9.9mm_P1.27mm | U1801, U1802, U1803, U1804, U1805, U1806, U1901, U1902 +8 |
| 4 | 74HC86 | DIP-14_W7.62mm | U2001, U2002, U3801, U3802 |
| 48 | PMOS | TSOT-23 | Q201, Q204, Q1002, Q1003, Q1901, Q2001, Q2101, Q2201 +40 |
| 48 | NMOS | TSOT-23 | Q202, Q203, Q1001, Q1004, Q1902, Q2002, Q2102, Q2203 +40 |
| 1 | Conn_01x12_Pin | Harwin_Gecko-G125-FVX1205L0X_2x06_P1.25mm_Vertical | J101 |
| 1 | Conn_01x34_Pin | Harwin_Gecko-G125-FVX3405L0X_2x17_P1.25mm_Vertical | J102 |
| 4 | 100nF | C_Disc_D5.0mm_W2.5mm_P5.00mm | C2001, C2002, C3801, C3802 |
Main logic design files
The KiCad project lives in the tmarhguy/alu repository on GitHub; these links point at the commit this page was built from.
Main logic: common questions
How big is the Main logic PCB?
The Main logic measures 98.5 × 95.5 mm, has 2 copper layers and is 1.6 mm thick.
How many components are on the Main logic?
122 components, from 7 distinct parts. The full bill of materials is listed on this page.
Where can I download the Main logic design files?
From the tmarhguy/alu repository on GitHub, which has the KiCad layout and the schematic; the links under Design files point to each one.
Can I use the Main logic design in my own project?
Yes, under the terms of its MIT license, which tmarhguy chose for the repository.
More boards in alu
Add sub
110 × 117 mm200 parts2LMIT47
Led panel 1
101 × 68 mm131 parts2LMIT47
Led panel 2
78.5 × 68.5 mm129 parts2LMIT47
Main control
59 × 63 mm42 parts2LMIT47
Led panel 3
43.5 × 50.5 mm35 parts2LMIT47
Flags
41 × 35.5 mm26 parts2LMIT47
Gate xnor 2in
77.5 × 43 mm16 parts2LMIT47
Gate xor 2in
72 × 42.5 mm16 parts2LMIT47
Gate and 4in
5.4 × 18.7 mm10 parts2LMIT47
Gate or 2in
57.5 × 36 mm6 parts2LMIT47
Gate and 2in
42.5 × 32.5 mm6 parts2LMIT47