4 layers406.4 × 50.8 mm
4 layers406.4 × 254 mm
Extmemory
mrieker/pdp8i- Size
- 406.4 × 254 mm
- Copper layers
- 4
- Thickness
- 1.6 mm
- Parts
- 113
- Nets
- 368
- Pads
- 1,160
- Tracks, vias
- 1,459, 210
- Pours
- 2
- Routed
- Yes
- KiCad
- KiCad 7 (file 20221018)
- Created
- 12 Oct 2026
- Updated
- 1 Nov 2026
Overview
Extmemory is an open-source printed circuit board by mrieker, from the mrieker/pdp8i repository on GitHub. It is a 4-layer board of 406.4 × 254 mm with 113 parts on 368 nets, routed with 1,459 tracks and 210 vias.
It is built around the 74AHC541D, 74AC153PC and 74HC30S, with the 74AHC04D, 74AHC00D and 74HC175D among its other parts. Its parts include 54 capacitors and 4 connectors.
Main components
12
74AHC541D
SO-20-300mil-40℃~+125℃ 1 2V~5.5V 74AHC 8 80uA 8mA 8mA 9ns@5.5V,50pF Schmitt trigger Tri-State Unidirectional SO-20-300mil Buffers, Drivers, Receivers, Transceivers ROHSNexperiaBuffer/Driver/Transceiver
74AC153PC
PDIP-16-40℃~+85℃ 24mA 24mA 2V~6V 4uA 6.5ns@5V,50pF 74AC Single Supply PDIP-16 Signal Switches, Multiplexers, Decoders ROHSonsemiSignal Switches, Multiplexers, Decoders
74HC30S
SOP-140℃~+60℃ 1 1.5V~4.2V 1.9V~5.9V 100mV 25ns@5.0V,15pF 2V~6V 5.2mA 5.2mA 5.5uA 500mV~1.8V 74HC Series 8 NAND Gate Push-pull SOP-14 Logic Gates ROHSGRLogic Gates74AHC04D
SOIC-14-40℃~+125℃ 1 1.5V~3.85V 1.9V、2.9V、4.4V 2V~5.5V 2uA 500mV~1.65V 6 7.5ns@5V,50pF 74AHC 8mA 8mA SOIC-14 Inverters ROHSNexperiaInverters74AHC00D
SOIC-14-40℃~+125℃ 1.5V~3.85V 2V~5.5V 2uA 4 500mV~1.65V 7.5ns@5V,50pF 74AHC Series 8mA 8mA NAND Gate SOIC-14 Logic Gates ROHSNexperiaLogic Gates
74HC175D
SOIC-16-40℃~+125℃ 0ns 1 13ns 24ns@6V,50pF 2V~6V 3pF 4 4uA 5.2mA 5.2mA 63MHz 74HC Series Asynchronous Complementary type D-Type Reset Rising Edge SOIC-16 Flip Flops ROHSToshibaFlip Flops74AHC74D
SOP-14-40℃~+125℃ 1 115MHz 2 2V~5.5V 2uA 3pF 500ps 5ns 74AHC Series 8mA 8mA 9.3ns@5V,50pF Asynchronous Complementary D-Type Rising Edge Set and Reset SOP-14 Flip Flops ROHSNexperiaFlip Flops
74AC10PC
DIP-14-40℃~+85℃ 1mV、1mV、2mV 2.1V~3.85V 2.99V、4.49V、5.49V 24mA 24mA 2V~6V 2uA 3 3 74AC Series 7ns@5V,50pF 900mV~1.65V NAND Gate DIP-14 Logic Gates ROHSonsemiLogic Gates74AC109PC
PDIP-16-40℃~+85℃ 1 10ns@5V,50pF 175MHz 2 24mA 24mA 2V~6V 2uA 4.5pF 74AC Series Complementary JK-Type Set and Reset PDIP-16 Flip Flops ROHSonsemiFlip Flops74AC11PC
DIP-14-40℃~+85℃ 100mV、440mV 2.1V~3.85V 2.46V、2.9V、3.76V、4.4V、4.76V、5.4V 24mA 24mA 2V~6V 2uA 3 3 74AC Series 8ns@5V,50pF 900mV~1.65V AND Gate DIP-14 Logic Gates ROHSonsemiLogic Gates74AC20M
SOIC-14SOIC-14 Inverters ROHSSTMicroelectronicsInverters74AHC08D
SOIC-14-40℃~+125℃ 1.5V~3.85V 1.9V、2.9V、4.4V 2 2V~5.5V 2uA 4 500mV~1.65V 550mV 7.9ns@5V,50pF 74AHC Series 8mA 8mA AND Gate SOIC-14 Logic Gates ROHSNexperiaLogic Gates
Parts
113| Qty | Value | Footprint | References |
|---|---|---|---|
| 54 | C | Resistor_THT:R_Axial_DIN0207_L6.3mm_D2.5mm_P7.62mm_Horizontal | C11, C12, C13, C14, C15, C21, C22, C23, C24, C25, C26, C27, C31, C32, C33, C34 +38 |
| 13 | 74AHC540 | Package_DIP:DIP-20_W7.62mm | E11, E14, E15, E21, E31, E41, E51, E53, E61, E64, E65, E71, E81 |
| 9 | 74AC153 | Package_DIP:DIP-16_W7.62mm | E43, E44, E54, E66, E75, E76, E77, E86, E87 |
| 5 | 74HC30 | Package_DIP:DIP-14_W7.62mm | E26, E33, E36, E46, E82 |
| 4 | 74AHC04 | Package_DIP:DIP-14_W7.62mm | E24, E27, E52, E56 |
| 4 | Conn_01x36 | Connector_PinHeader_2.54mm:PinHeader_1x36_P2.54mm_Vertical | J1, J2, J3, J4 |
| 3 | 74AHC00 | Package_DIP:DIP-14_W7.62mm | E34, E45, E63 |
| 3 | 74HC175 | Package_DIP:DIP-16_W7.62mm | E73, E84, E85 |
| 2 | 74AHC541 | Package_DIP:DIP-20_W7.62mm | E13, E32 |
| 2 | 74AHC74 | Package_DIP:DIP-14_W7.62mm | E37, E72 |
| 2 | CY7C199 | Package_DIP:DIP-28_W7.62mm | E12, E22 |
| 1 | 74AC10 | Package_DIP:DIP-14_W7.62mm | E83 |
| 1 | 74AC109 | Package_DIP:DIP-16_W7.62mm | E55 |
| 1 | 74AC11 | Package_DIP:DIP-14_W7.62mm | E23 |
| 1 | 74AC20 | Package_DIP:DIP-14_W7.62mm | E57 |
| 1 | 74AHC08 | Package_DIP:DIP-14_W7.62mm | E62 |
| 1 | 74AHC157 | Package_DIP:DIP-16_W7.62mm | E74 |
| 1 | 74AHC174 | Package_DIP:DIP-16_W7.62mm | E67 |
| 1 | 74HC21 | Package_DIP:DIP-14_W7.62mm | E25 |
| 1 | 74HC27 | Package_DIP:DIP-14_W7.62mm | E35 |
| 1 | 74HC42 | Package_DIP:DIP-16_W7.62mm | E47 |
| 1 | 74HC75 | Package_DIP:DIP-16_W7.62mm | E42 |
| 1 | LOGO | myfoots:bwlogo15 | G*** |
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Questions
How big is the Extmemory PCB?
It measures 406.4 × 254 mm and has 4 copper layers, 1.6 mm thick.
What parts does the Extmemory use?
113 parts, built around the 74AHC541D, 74AC153PC, 74HC30S and 74AHC04D. 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 Extmemory KiCad files?
From the mrieker/pdp8i repository on GitHub, at the commit this page was made from: the board is kicads/extmemory/extmemory.kicad_pcb and its schematic kicads/backplane/backplane.kicad_sch. PCBKit opens the board in the browser, with nothing to install.
Can I use the Extmemory design in my own project?
Its repository states no licence, so its author keeps all rights: ask mrieker before reusing the design.