Discrete6502
About the Discrete6502 PCB
Discrete6502 is an open source Raspberry Pi PCB design by epatel, published on GitHub under the CC-BY-NC-4.0 license. It is a board, with 5421 components from 47 distinct parts.
Its main chip is the Pico2_W_site, from the Raspberry Pi family. By type, the board carries 4051 transistors, 1110 resistors, 156 capacitors, 67 diodes, 36 test points and 1 IC.
It belongs with the retro computing designs in this gallery.
From the project
A MOS 6502 CPU rebuilt from 4,051 discrete transistors on a 291x322mm six-layer board that reproduces the original die layout
A complete, verified design for a MOS 6502 CPU built from 4,051 discrete surface-mount transistors (3,996 logic + 55 LED drivers), laid out as a 291 × 322 mm six-layer PCB that visually reproduces the original 6502 die — every FET sits at its transistor's die-true position, 55 LEDs blink the register bits in place, and a ring of die-scaled bond pads around the edge takes crocodile clips.
Main components on the Discrete6502
Discrete6502 bill of materials (BOM)
5421 components, 47 distinct parts — part numbers from the project's BOM.
| Qty | Part | Footprint | Refs |
|---|---|---|---|
| 1 | Pico2_W_site | RaspberryPi_Pico_W_SMD | U1 |
| 4051 | BSS138K | SOT-323_SC-70 | Q1, Q2, Q3, Q4, Q5, Q6, Q7, Q8 +4043 |
| 1 | AB0 | TestPoint_THTPad_4.0x4.0mm_Drill2.0mm | TP1 |
| 1 | AB1 | TestPoint_THTPad_4.0x4.0mm_Drill2.0mm | TP2 |
| 1 | AB2 | TestPoint_THTPad_4.0x4.0mm_Drill2.0mm | TP3 |
| 1 | AB3 | TestPoint_THTPad_4.0x4.0mm_Drill2.0mm | TP4 |
| 1 | AB4 | TestPoint_THTPad_4.0x4.0mm_Drill2.0mm | TP5 |
| 1 | AB5 | TestPoint_THTPad_4.0x4.0mm_Drill2.0mm | TP6 |
| 1 | AB6 | TestPoint_THTPad_4.0x4.0mm_Drill2.0mm | TP7 |
| 1 | AB7 | TestPoint_THTPad_4.0x4.0mm_Drill2.0mm | TP8 |
| 1 | AB8 | TestPoint_THTPad_4.0x4.0mm_Drill2.0mm | TP9 |
| 1 | AB9 | TestPoint_THTPad_4.0x4.0mm_Drill2.0mm | TP10 |
| 1 | AB10 | TestPoint_THTPad_4.0x4.0mm_Drill2.0mm | TP11 |
| 1 | AB11 | TestPoint_THTPad_4.0x4.0mm_Drill2.0mm | TP12 |
| 1 | AB12 | TestPoint_THTPad_4.0x4.0mm_Drill2.0mm | TP13 |
| 1 | AB13 | TestPoint_THTPad_4.0x4.0mm_Drill2.0mm | TP14 |
| 1 | AB14 | TestPoint_THTPad_4.0x4.0mm_Drill2.0mm | TP15 |
| 1 | AB15 | TestPoint_THTPad_4.0x4.0mm_Drill2.0mm | TP16 |
| 1 | DB0 | TestPoint_THTPad_4.0x4.0mm_Drill2.0mm | TP17 |
| 1 | DB1 | TestPoint_THTPad_4.0x4.0mm_Drill2.0mm | TP18 |
Show 27 more
| Qty | Part | Footprint | Refs |
|---|---|---|---|
| 1 | DB2 | TestPoint_THTPad_4.0x4.0mm_Drill2.0mm | TP19 |
| 1 | DB3 | TestPoint_THTPad_4.0x4.0mm_Drill2.0mm | TP20 |
| 1 | DB4 | TestPoint_THTPad_4.0x4.0mm_Drill2.0mm | TP21 |
| 1 | DB5 | TestPoint_THTPad_4.0x4.0mm_Drill2.0mm | TP22 |
| 1 | DB6 | TestPoint_THTPad_4.0x4.0mm_Drill2.0mm | TP23 |
| 1 | DB7 | TestPoint_THTPad_4.0x4.0mm_Drill2.0mm | TP24 |
| 1 | CLK0 | TestPoint_THTPad_4.0x4.0mm_Drill2.0mm | TP25 |
| 1 | CLK1OUT | TestPoint_THTPad_4.0x4.0mm_Drill2.0mm | TP26 |
| 1 | CLK2OUT | TestPoint_THTPad_4.0x4.0mm_Drill2.0mm | TP27 |
| 1 | RES | TestPoint_THTPad_4.0x4.0mm_Drill2.0mm | TP28 |
| 1 | RDY | TestPoint_THTPad_4.0x4.0mm_Drill2.0mm | TP29 |
| 1 | IRQ | TestPoint_THTPad_4.0x4.0mm_Drill2.0mm | TP30 |
| 1 | NMI | TestPoint_THTPad_4.0x4.0mm_Drill2.0mm | TP31 |
| 1 | RW | TestPoint_THTPad_4.0x4.0mm_Drill2.0mm | TP32 |
| 1 | SYNC | TestPoint_THTPad_4.0x4.0mm_Drill2.0mm | TP33 |
| 1 | SO | TestPoint_THTPad_4.0x4.0mm_Drill2.0mm | TP34 |
| 1 | VSS | TestPoint_THTPad_4.0x4.0mm_Drill2.0mm | TP35 |
| 1 | VCC | TestPoint_THTPad_4.0x4.0mm_Drill2.0mm | TP36 |
| 55 | C2286 LED_RED | LED_0603_1608Metric | D1, D2, D3, D4, D5, D6, D7, D8 +47 |
| 12 | 1N4148WS | D_SOD-323 | D56, D57, D58, D59, D60, D61, D62, D63 +4 |
| 96 | 100NF 100nF | C_0402_1005Metric | C1, C2, C3, C4, C5, C6, C7, C8 +88 |
| 4 | 10UF 10uF | C_0805_2012Metric | C97, C98, C99, C100 |
| 56 | 100pF-DNP | C_0402_1005Metric | C101, C102, C103, C104, C105, C106, C107, C108 +48 |
| 1023 | 10K 10k | R_0402_1005Metric | R1, R2, R3, R4, R5, R6, R7, R8 +1015 |
| 55 | 2.2K 2.2k | R_0402_1005Metric | R1019, R1020, R1021, R1022, R1023, R1024, R1025, R1026 +47 |
| 6 | 100R | R_0402_1005Metric | R1074, R1075, R1076, R1077, R1078, R1079 |
| 26 | 1k | R_0402_1005Metric | R1085, R1086, R1087, R1088, R1089, R1090, R1091, R1092 +18 |
Discrete6502 design files
The KiCad project lives in the epatel/discrete6502 repository on GitHub; these links point at the commit this page was built from.
Discrete6502: common questions
What microcontroller does the Discrete6502 use?
The Discrete6502 is built around the Pico2_W_site, from the Raspberry Pi family.
How many components are on the Discrete6502?
5421 components, from 47 distinct parts, with part numbers taken from the project's own BOM. The full bill of materials is listed on this page.
Where can I download the Discrete6502 design files?
From the epatel/discrete6502 repository on GitHub, which has a netlist and the BOM; the links under Design files point to each one.
Can I use the Discrete6502 design in my own project?
It is published under CC-BY-NC-4.0, which limits how it may be reused; read the license before building on it.
Can I test firmware for the Discrete6502 without the hardware?
Yes. HardLabs builds a simulation of the board from its netlist and BOM, so you can run and debug Raspberry Pi firmware against it before you order a PCB.
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