ALU
About the ALU PCB
ALU is an open source PCB design by AJain9199, published on GitHub. It is a 4-layer board measuring 100 × 100 mm, with 70 components from 21 distinct parts.
Other key parts include the SN74AHCT16245DGGR, 74AHC1G08, 74FCT16374CTPVG, 74AHC1G04DBVR and 74LS181. By type, the board carries 36 capacitors, 22 ICs, 9 connectors, 2 resistors and 1 diode.
From the project
Since each 74LS181 chip only handles 4 bits, 4 of these chips need to be used together. Instead of cascading them using the built-in carry outputs, I used full look-ahead carry generation which is more than 2x faster (sn54s181) (realistically both are fine at the speeds this work
Since each 74LS181 chip only handles 4 bits, 4 of these chips need to be used together. Instead of cascading them using the built-in carry outputs, I used full look-ahead carry generation which is more than 2x faster (sn54s181) (realistically both are fine at the speeds this works at, this is simply future/idiot proofing) But I couldn't find the carry generation chip, the 182, so I replicated the internal circuit using discrete (A)HCT gates (sn54s182).
Main components on the ALU
ALU bill of materials (BOM)
70 components, 21 distinct parts.
| Qty | Part | Footprint | Refs |
|---|---|---|---|
| 1 | SN74AHCT16245DGGR | TSSOP-48_6.1x12.5mm_P0.5mm | IC1 |
| 2 | 74AHC1G08 | SOT-23-5 | U1, U17 |
| 2 | 74FCT16374CTPVG SN74AHCT16374DGGR | TSSOP-48_6.1x12.5mm_P0.5mm | U2, U18 |
| 1 | 74AHC1G04DBVR | SOT-23-5 | U3 |
| 3 | 74LS181 | DIP-24_W15.24mm_Socket | U4, U5, U9 |
| 4 | 74AHCT1G08DBVR | SOT-23-5 | U6, U13, U14, U19 |
| 1 | 74HCT11 | SOIC-14_3.9x8.7mm_P1.27mm | U7 |
| 1 | 74FCT16374CTPVG 74LS181 | DIP-24_W15.24mm_Socket | U8 |
| 1 | 74FCT16374CTPVG 74HCT21 | SOIC-14_3.9x8.7mm_P1.27mm | U10 |
| 3 | 74AHC1G32DBVR | SOT-23-5 | U11, U15, U16 |
| 3 | 74AHCT1G02DBVR | SOT-23-5 | U12, U20, U21 |
| 1 | Conn_01x06_Pin | PinHeader_1x06_P2.54mm_Vertical | J1 |
| 3 | Conn_02x15_Odd_Even | IDC-Header_2x15_P2.54mm_Vertical | J2, J3, J4 |
| 4 | Conn_01x01_Pin | PinHeader_1x01_P2.54mm_Vertical | J5, J6, J7, J8 |
| 1 | Conn_01x02 | PinHeader_1x02_P2.54mm_Vertical | J9 |
| 1 | LED | LED_0603_1608Metric | D1 |
| 23 | 0.1uF | C_0603_1608Metric | C1, C6, C7, C8, C9, C10, C11, C12 +15 |
| 12 | 0.01uF | C_0603_1608Metric | C2, C3, C4, C5, C25, C26, C27, C28 +4 |
| 1 | 100uF | CP_Elec_5x5.3 | C36 |
| 1 | 1k | R_0603_1608Metric | R1 |
Show 1 more
| Qty | Part | Footprint | Refs |
|---|---|---|---|
| 1 | 100 | R_0603_1608Metric | R2 |
ALU design files
The KiCad project lives in the AJain9199/AOS16 repository on GitHub; these links point at the commit this page was built from.
- LayoutALU/ALU.kicad_pcb
- SchematicALU/ALU.kicad_sch
ALU: common questions
How big is the ALU PCB?
The ALU measures 100 × 100 mm, has 4 copper layers and is 1.6 mm thick.
How many components are on the ALU?
70 components, from 21 distinct parts. The full bill of materials is listed on this page.
Where can I download the ALU design files?
From the AJain9199/AOS16 repository on GitHub, which has the KiCad layout and the schematic; the links under Design files point to each one.
Can I use the ALU design in my own project?
The repository has no license, so all rights stay with AJain9199. Use it as a reference, and ask the author before reusing the design.
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