2 layers229.9 × 93.3 mm
2 layers229.9 × 83.8 mm
Processor attempt 4
ethanjamesauto/modular_8bit_computer2- Size
- 229.9 × 83.8 mm
- Copper layers
- 2
- Thickness
- 1.6 mm
- Parts
- 352
- Nets
- 516
- Pads
- 1,681
- Tracks, vias
- 3,123, 169
- Routed
- Yes
- KiCad
- KiCad 7 (file 20221018)
- Created
- 18 Aug 2024
- Updated
- 8 Nov 2025
Overview
Processor attempt 4 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 352 parts on 516 nets, routed with 3,123 tracks and 169 vias.
It is built around the A13, 74LS245SC and 74LS367PC, with the 74LS273PC, 74LS161DC and 74LS00SC among its other parts. Its parts include 121 resistors, 114 diodes, 61 connectors, 51 ICs and 2 capacitors.
Main components
12A13
TQFP-176(20x20)TQFP-176(20x20) Microcontrollers (MCU/MPU/SOC) ROHSAllwinner TechMicrocontroller Units (MCUs/MPUs/SOCs)74LS245SC
-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
74LS367PC
PDIP-16Buffers, Drivers, Receivers, TransceiversTexas Instruments
74LS273PC
PDIP-201 15ns 27mA 27ns@5V,15pF 30MHz 5ns 74LS Series 8 D-Type Reset Rising Edge PDIP-20 Flip Flops ROHSonsemiFlip Flops
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
74LS00SC
-0℃~+70℃ 15ns@5V,50pF 2 2.7V 2V 4 4.75V~5.25V 400uA 500mV 74LS 800mV 8mA NAND Gate - Logic Gates ROHSTexas InstrumentsLogic Gates
74LS04PC
PDIP-140℃~+70℃ 4.75V~5.25V 6 6.6mA 74LS PDIP-14 InvertersonsemiInverters74LS30PC
PDIP-140℃~+70℃ 1 1.1mA 18ns@5V,50pF、20ns@5V,50pF 2.7V 2V 4.75V~5.25V 400uA 500mV 74LS Series 8 800mV 8mA NAND Gate PDIP-14 Logic GatesTexas InstrumentsLogic Gates
74LS32SC
-- Logic Gates ROHSTexas InstrumentsLogic Gates74LS574N
-0ns 0℃~+70℃ 1 2.6mA 20ns 24mA 28ns@5V,45pF 35MHz 4.75V~5.25V 74LS Series 8 D-Type Rising Edge Tri-State - Flip Flops ROHSRochester Electronics, LLCFlip Flops
74HC688D
SOIC-20-300mil-40℃~+125℃ 0.1V 0.5V、1.35V、1.8V 1.2V、2.4V、3.2V 1.9V、4.4V、5.9V 160uA 16ns@6.0V,50pF 2V~5V SOIC-20-300mil Digital Comparators ROHSNexperiaDigital Comparators
74LVC1G08Z
SOT-553-5-40℃~+125℃ 1 1.65V~5.5V 1.7V、2V 2 2.4V、3.8V 32mA 32mA 4ns@5V,50pF 550mV、800mV 700mV、800mV 74LVC Series AND Gate SOT-553-5 Logic Gates ROHSDiodes IncorporatedLogic Gates
README
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
352| Qty | Value | Footprint | References |
|---|---|---|---|
| 106 | 470 | Resistor_SMD:R_0603_1608Metric_Pad0.98x0.95mm_HandSolder | r107, r108, r109, r110, r110, r111, r111, r112, r112, r113, r113, r114, r114, r115, r115, r116 +90 |
| 69 | A0 | LED_SMD:LED_0603_1608Metric_Pad1.05x0.95mm_HandSolder | D1, D17, D25, D33, D41, D49, D49, D50, D50, D51, D51, D52, D52, D53, D53, D54 +53 |
| 23 | J | Connector_PinHeader_2.54mm:PinHeader_1x01_P2.54mm_Vertical | J36, J37, J41, J43, J44, J46, J47, J48, J49, J50, J51, J52, J57, J60, J62, J64 +7 |
| 17 | Conn_01x08_Pin | Connector_PinHeader_2.54mm:PinHeader_1x08_P2.54mm_Vertical | J4, J20, J22, J22, J23, J24, J24, J25, J25, J26, J26, J27, J28, J28, J29, J29 +1 |
| 12 | 0 | Resistor_SMD:R_0603_1608Metric_Pad0.98x0.95mm_HandSolder | R107, R108, R109, R118, R119, R120, R129, R130, R141, R142, R145, R146 |
| 9 | 74LS273 | Package_DIP:DIP-20_W7.62mm_Socket | U6, U7, U24, U27, U37, U40, U41, U44, U45 |
| 7 | 74LS138 | Package_DIP:DIP-16_W7.62mm_Socket | U36, U57, U58, U58, U59, U59, U60 |
| 7 | 74LS245 | Package_DIP:DIP-20_W7.62mm_Socket | U21, U23, U29, U30, U31, U49, U50 |
| 6 | A4 | LED_SMD:LED_0603_1608Metric_Pad1.05x0.95mm_HandSolder | D5, D21, D29, D37, D45, D82 |
| 6 | Conn_01x03_Pin | Connector_PinHeader_2.54mm:PinHeader_1x03_P2.54mm_Vertical | J1, J31, J32, J33, J34, J69 |
| 5 | A1 | LED_SMD:LED_0603_1608Metric_Pad1.05x0.95mm_HandSolder | D2, D18, D26, D34, D42 |
| 5 | A2 | LED_SMD:LED_0603_1608Metric_Pad1.05x0.95mm_HandSolder | D3, D19, D27, D35, D43 |
| 5 | A3 | LED_SMD:LED_0603_1608Metric_Pad1.05x0.95mm_HandSolder | D4, D20, D28, D36, D44 |
| 5 | A5 | LED_SMD:LED_0603_1608Metric_Pad1.05x0.95mm_HandSolder | D6, D22, D30, D38, D46 |
| 5 | A6 | LED_SMD:LED_0603_1608Metric_Pad1.05x0.95mm_HandSolder | D7, D23, D31, D39, D47 |
| 5 | A7 | LED_SMD:LED_0603_1608Metric_Pad1.05x0.95mm_HandSolder | D8, D24, D32, D40, D48 |
| 4 | 74LS161 | Package_DIP:DIP-16_W7.62mm_Socket | U2, U3, U4, U5 |
| 4 | 74LS367 | Package_DIP:DIP-16_W7.62mm_Socket | U38, U47, U48, U51 |
| 4 | Conn_01x01_Pin | Connector_PinHeader_2.54mm:PinHeader_1x01_P2.54mm_Vertical | J30, J35, J40, J42 |
| 4 | Conn_01x06_Pin | Connector_PinHeader_2.54mm:PinHeader_1x06_P2.54mm_Vertical | J14, J15, J16, J17 |
| 4 | Conn_01x10_Pin | Connector_PinHeader_2.54mm:PinHeader_1x10_P2.54mm_Vertical | J8, J18, J19, J19 |
| 3 | R | Resistor_SMD:R_0603_1608Metric_Pad0.98x0.95mm_HandSolder | R1, R2, R142 |
| 2 | 28C256 | Package_DIP:DIP-28_W15.24mm_Socket | U18, U19 |
| 2 | 74LS00 | Package_DIP:DIP-14_W7.62mm_Socket | U52, U53 |
| 2 | 74LS04 | Package_DIP:DIP-14_W7.62mm_Socket | U42, U56 |
| 2 | 74LS283 | Package_DIP:DIP-16_W7.62mm_Socket | U32, U39 |
| 2 | 74LS30 | Package_DIP:DIP-14_W7.62mm_Socket | U35, U55 |
| 2 | 74LS32 | Package_DIP:DIP-14_W7.62mm_Socket | U33, U34 |
| 2 | 74LS574 | Package_DIP:DIP-20_W7.62mm_Socket | U25, U26 |
| 2 | C | Capacitor_SMD:C_1206_3216Metric | C1, C2 |
| 1 | 1 | Resistor_SMD:R_1206_3216Metric | 5V_rsns1 |
| 1 | 10k | Resistor_SMD:R_1206_3216Metric | 5V_rsns2 |
| 1 | 5V_RAW | LED_SMD:LED_0603_1608Metric_Pad1.05x0.95mm_HandSolder | D81 |
| 1 | 74HC688 | Package_DIP:DIP-20_W7.62mm_Socket | U43 |
| 1 | 74LVC1G08 | Package_TO_SOT_SMD:SOT-23-6_Handsoldering | U61 |
| 1 | A10 | LED_SMD:LED_0603_1608Metric_Pad1.05x0.95mm_HandSolder | D11 |
| 1 | A11 | LED_SMD:LED_0603_1608Metric_Pad1.05x0.95mm_HandSolder | D12 |
| 1 | A12 | LED_SMD:LED_0603_1608Metric_Pad1.05x0.95mm_HandSolder | D13 |
| 1 | A13 | LED_SMD:LED_0603_1608Metric_Pad1.05x0.95mm_HandSolder | D14 |
| 1 | A14 | LED_SMD:LED_0603_1608Metric_Pad1.05x0.95mm_HandSolder | D15 |
| 1 | A15 | LED_SMD:LED_0603_1608Metric_Pad1.05x0.95mm_HandSolder | D16 |
| 1 | A8 | LED_SMD:LED_0603_1608Metric_Pad1.05x0.95mm_HandSolder | D9 |
| 1 | A9 | LED_SMD:LED_0603_1608Metric_Pad1.05x0.95mm_HandSolder | D10 |
| 1 | Clock_Aux_Latch_0 | Connector_PinHeader_2.54mm:PinHeader_1x01_P2.54mm_Vertical | J39 |
| 1 | Conn_01x40_Pin | Connector_PinHeader_2.54mm:PinHeader_1x40_P2.54mm_Horizontal | J3 |
| 1 | DB9_Female_MountingHoles | Connector_Dsub:DSUB-9_Female_Horizontal_P2.77x2.84mm_EdgePinOffset4.94mm_Housed_MountingHolesOffset7.48mm | J21 |
| 1 | HM62256BLP | Package_DIP:DIP-28_W15.24mm | U28 |
| 1 | HM62256BLP | Package_SO:SOIC-28W_7.5x18.7mm_P1.27mm | U46 |
| 1 | LOGO | AudioJacks:plant | G*** |
| 1 | NE555D | Package_SO:SOIC-8_3.9x4.9mm_P1.27mm | U1 |
| 1 | ~ | Package_DIP:DIP-16_W7.62mm_Socket | U62 |
Questions
How big is the Processor attempt 4 PCB?
It measures 229.9 × 83.8 mm and has 2 copper layers, 1.6 mm thick.
What parts does the Processor attempt 4 use?
352 parts, built around the A13, 74LS245SC, 74LS367PC and 74LS273PC. 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 Processor attempt 4 KiCad files?
From the ethanjamesauto/modular_8bit_computer repository on GitHub, at the commit this page was made from: the board is processor_attempt_4/processor_attempt_4.kicad_pcb. PCBKit opens the board in the browser, with nothing to install.
Can I use the Processor attempt 4 design in my own project?
Its repository states no licence, so its author keeps all rights: ask ethanjamesauto before reusing the design.
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