2 layers229.9 × 93.3 mm
2 layers48.3 × 73.7 mm
25aa1024 static
ethanjamesauto/modular_8bit_computer2- Size
- 48.3 × 73.7 mm
- Copper layers
- 2
- Thickness
- 1.6 mm
- Parts
- 13
- Nets
- 210
- Pads
- 210
- Tracks, vias
- 0, 0
- Routed
- Not yet
- KiCad
- KiCad 7 (file 20221018)
- Created
- 18 Aug 2024
- Updated
- 8 Nov 2025
Overview
25aa1024 static 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 48.3 × 73.7 mm with 13 parts on 210 nets.
It is built around the 74HC595, 74LS00SC and 74LS153DC, with the 74LS393P-E and NE555D among its other parts. Its parts include 11 ICs and 2 connectors.
Main components
5
74HC595
SOP-16-40℃~+85℃ 1 100ns@5V,50pF 10MHz 2V~6V 74HC 8 Serial-to-Serial or Parallel Tri-State SOP-16 Shift Registers ROHSGRShift Registers
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
74LS153DC
PDIP-160℃~+70℃ 14ns 4.75V~5.25V 400uA 400uA 6.2mA 74LS Single Supply Tri-state output PDIP-16 Signal Switches, Multiplexers, Decoders ROHSTexas InstrumentsSignal Switches, Multiplexers, Decoders
74LS393P-E
DIP-14-20℃~+75℃ 2 35MHz 4 4.75V~5.25V 400mW 40ns@5V,15pF 74LS Binary Counter Reset function DIP-14 Counters, Dividers ROHSRenesas ElectronicsCounters, Dividers
NE555D
SOIC-80℃~+70℃ 10mA 4.5V~16V SOIC-8 555 Timers / Counters ROHSTexas InstrumentsTimers / Counters
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
13| Qty | Value | Footprint | References |
|---|---|---|---|
| 4 | 74HC595 | Package_SO:SOIC-16_3.9x9.9mm_P1.27mm | U2, U7, U8, U9 |
| 2 | 74LS00 | Package_DIP:DIP-14_W7.62mm | U4, U10 |
| 2 | 74LS153 | Package_DIP:DIP-16_W7.62mm | U3, U6 |
| 2 | Conn_01x28_Pin | Connector_PinHeader_2.54mm:PinHeader_1x28_P2.54mm_Vertical | J1, J2 |
| 1 | 74LS393 | Package_DIP:DIP-14_W7.62mm | U5 |
| 1 | NE555D | Package_DIP:DIP-8_W7.62mm | U11 |
| 1 | ~ | Package_DIP:DIP-8_W7.62mm | U1 |
Questions
How big is the 25aa1024 static PCB?
It measures 48.3 × 73.7 mm and has 2 copper layers, 1.6 mm thick.
What parts does the 25aa1024 static use?
13 parts, built around the 74HC595, 74LS00SC, 74LS153DC and 74LS393P-E. 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 25aa1024 static KiCad files?
From the ethanjamesauto/modular_8bit_computer repository on GitHub, at the commit this page was made from: the board is 93c46a_type/25aa1024/25aa1024_static/25aa1024_static.kicad_pcb. PCBKit opens the board in the browser, with nothing to install.
Can I use the 25aa1024 static 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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