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 layers160 × 35.6 mm
ZX Spectrum Issue 1 32K RAM PCB
- Size
- 160 × 35.6 mm
- Copper layers
- 2
- Thickness
- 1.6 mm
- Parts
- 27
- Nets
- 50
- Pads
- 247
- Tracks, vias
- 966, 28
- Pours
- 12
- Routed
- Yes
- KiCad
- KiCad 10.0 (file 20260206)
- Created
- 23 Oct 2026
- Updated
- 26 Oct 2026
Overview
Issue1 is an open-source printed circuit board by liveboxandy, from the liveboxandy/ZX-Spectrum-Issue-1-32K-RAM-PCB repository on GitHub, published under the CC0-1.0 licence. It is a 2-layer board of 160 × 35.6 mm with 27 parts on 50 nets, routed with 966 tracks and 28 vias.
It is built around the 74LS157PC, 74LS00SC and 74LS32SC. Its parts include 12 ICs, 10 capacitors and 2 resistors.
Main components
3
74LS157PC
PDIP-160℃~+70℃ 4.75V~5.25V Single Supply PDIP-16 Signal Switches, Multiplexers, Decoders ROHSTexas InstrumentsSignal Switches, Multiplexers, Decoders
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
74LS32SC
-- Logic Gates ROHSTexas InstrumentsLogic Gates
README
README.mdThis is a Kicad 10 project and was only used to create an ibom to assist in the debugging of faulty boards. Use at your own risk.
Kicad does not like handrawn tracks, it only like straight lines so I have followed the route for each track but it does not track exactly but close enough for the user to find the track when debugging.
If a track originally went between two pins on the front side, it still does. If it went between two traces it still goes between the same two traces.
The ZX Spectrum Issue 1 32K RAM PCB used has an MFG date of 1982 and has a silkscreen FAB revision of SRC091, a topside FAB revision of SRC080 A and a solder side FAB revision of SRC097 B.
The created schematic was based on the physical layout of a raw PCB with known components. The resistor values were taken from a image of a populated PCB but it was impossible to determine the values of the capacitors used so I used the values from a ZX Spectrum Issue 2 schematic 32K Expansion for the smoothing caps (C3-C10). The values of C1 and C2 are also the values used in the Issue 2 schematic.
Note that the address lines A0 to A14 through the LS157 to the RAM chips do not appear to route as expected but agree with the PCB tracking.
I would not use these gerbers to manufacture a PCB without a lot more checking.
Have fun.
Parts
27| Qty | Value | Footprint | References |
|---|---|---|---|
| 8 | 4532 | Package_DIP:DIP-16_W7.62mm | IC3, IC4, IC5, IC6, IC7, IC8, IC9, IC10 |
| 8 | 47nF | Capacitor_THT:C_Disc_D4.7mm_W2.5mm_P5.00mm | C1, C2, C3, C4, C5, C6, C7, C8 |
| 2 | 220R | MOD:R_Axial_L7.8mm_D2.4mm_P12.7mm_Horizontal | R1, R2 |
| 2 | 74LS157 | Package_DIP:DIP-16_W7.62mm | IC1, IC2 |
| 1 | 100pF | MOD:C_Axial_L7.8mm_D2.4mm_P12.70mm_Horizontal | C9 |
| 1 | 3 4 | Connector_PinSocket_2.54mm:PinSocket_1x03_P2.54mm_Vertical | 3-4 |
| 1 | 47pF | MOD:C_Axial_L7.8mm_D2.4mm_P12.70mm_Horizontal | C10 |
| 1 | 74LS00 | Package_DIP:DIP-14_W7.62mm | IC12 |
| 1 | 74LS32 | Package_DIP:DIP-14_W7.62mm | IC11 |
| 1 | LHS | MOD:DIP-16_W7.62mm_Socket | EXT1 |
| 1 | RHS | MOD:DIP-16_W7.62mm_Socket | EXT2 |
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Questions
How big is the Issue1 PCB?
It measures 160 × 35.6 mm and has 2 copper layers, 1.6 mm thick.
What parts does the Issue1 use?
27 parts, built around the 74LS157PC, 74LS00SC and 74LS32SC. 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 Issue1 KiCad files?
From the liveboxandy/ZX-Spectrum-Issue-1-32K-RAM-PCB repository on GitHub, at the commit this page was made from: the board is Issue1.kicad_pcb and its schematic Issue1.kicad_sch. PCBKit opens the board in the browser, with nothing to install.
Can I use the Issue1 design in my own project?
Its repository publishes it under the CC0-1.0 licence: you may reuse it on that licence's terms (keep the author's notice, and for a copyleft licence share your changes alike).