2 layers299.7 × 198.1 mm
Cisc-8
nailed-barnacle/Cisc-8-ttl-processor
A cut-down version of the 8080 processor using HCTTL and including a discrete ALU and instruction decoder
319 parts1MIT
2 layers297 × 210 mm
MASIC CPU schematics and PCB
- Size
- 297 × 210 mm
- Copper layers
- 2
- Thickness
- 1.6 mm
- Parts
- 197
- Nets
- 385
- Pads
- 1,880
- Tracks, vias
- 11,611, 585
- Pours
- 2
- Routed
- Yes
- KiCad
- KiCad 7 (file 20221018)
- Created
- 3 Oct 2026
- Updated
- 3 Oct 2026
Overview
Cpu is an open-source printed circuit board by tetrix450, from the tetrix450/masic-cpu repository on GitHub, published under the MIT licence. It is a 2-layer board of 297 × 210 mm with 197 parts on 385 nets, routed with 11,611 tracks and 585 vias.
It is built around the 74HC245D, 74HC163D and 74HC273D, with the 74HC32D, 74HC193D and 74HC04D among its other parts. Its parts include 88 capacitors, 73 ICs, 23 resistors, 7 connectors and 1 switch.
Main components
12
74HC245D
SO-20-300mil-40℃~+125℃ 1 160uA 2V~6V 7.8mA 7.8mA 74HC 8 9ns@4.5V,50pF Bidirectional Tri-State SOIC-20-300mil Buffers, Drivers, Receivers, Transceivers ROHSNexperiaBuffers, Drivers, Receivers, Transceivers
74HC163D
SO-16-40℃~+125℃ 1 16ns@6V,50pF 2V~6V 4 500mW 55MHz 74HC Divide-by-2 Reset function、Cascade counter、Synchronous counting Rising Edge Synchronous Synchronous Up Counter SO-16 Counters, Dividers ROHSNexperiaCounters / Dividers74HC273D
SOIC-20-300mil-40℃~+125℃ 1 12ns 15ns@4.5V,50pF 2V~6V 3.5pF 30MHz 3ns 74HC Series 8 8uA D-Type Reset Rising Edge SO-20-300mil Flip Flops ROHSNexperiaFlip Flops
74HC32D
SOP-14-40℃~+125℃ 1.5V~4.2V 1.9V、4.4V、5.9V 100mV、400mV、400mV 2 2V~6V 2uA 4 5.2mA 5.2mA 500mV~1.8V 6ns@6V,50pF 74HC Series OR Gate SOIC-14 Logic Gates ROHSNexperiaLogic Gates74HC193D
SO-16-40℃~+125℃ 1 18ns@6V 2V~6V 4 49MHz 500mW 74HC Asynchronous Divide-by-2 Reset function、Synchronous counting、Asynchronous parallel load、Multi-mode counting Rising Edge Synchronous Up Counter、Down Counter SO-16 Counters, Dividers ROHSNexperiaCounters / Dividers74HC04D
SOP-14-40℃~+125℃ 1 1.5V~4.2V 1.9V、3.7V、5.2V 100mV、400mV、400mV 14ns@6V,50pF 2V~6V 2uA 5.2mA 5.2mA 500mV~1.8V 6 74HC SOIC-14 Inverters ROHSNexperiaInverters74HC08D
SOP-14-40℃~+125℃ 1.5V~4.2V 1.9V、3.7V、5.2V 100mV、400mV 2 27ns@4.5V,50pF 2V~6V 2uA 4 5.2mA 5.2mA 500mV~1.8V 74HC Series AND Gate SOIC-14 Logic Gates ROHSNexperiaLogic Gates
74HC138
SOP-160℃~+70℃ 24ns@5.0V,16pF 2V~6V 3/8 5.2mA 5.2mA 5uA 74HC Decoder Reverse function Single Supply SOP-16 Signal Switches, Multiplexers, Decoders ROHSGRSignal Switches, Multiplexers, Decoders74HC151D
SOIC-16-40℃~+125℃ 15ns@5V,15pF 2V~6V 40uA 5.2mA 5.2mA 74HC 8/1 Multiplexer Single Supply SOIC-16 Signal Switches, Multiplexers, Decoders ROHSToshibaSignal Switches / Encoders & Decoders / Multiplexers
74HC283P-E
-- Specialty Logic ROHSRenesas ElectronicsSpecialty Logic
74LS157PC
PDIP-160℃~+70℃ 4.75V~5.25V Single Supply PDIP-16 Signal Switches, Multiplexers, Decoders ROHSTexas InstrumentsSignal Switches, Multiplexers, Decoders74HC11D
SOP-14-40℃~+125℃ 1.5V~4.2V 1.9V、4.4V、5.9V 100mV、100mV、100mV 17ns@6V,50pF 2V~6V 2uA 3 3 5.2mA 5.2mA 500mV~1.8V 74HC Series AND Gate SOP-14 Logic Gates ROHSNexperiaLogic Gates
Parts
197| Qty | Value | Footprint | References |
|---|---|---|---|
| 73 | 100n | cpu_pcb:C_Disc_7.62mm | C1, C2, C10, C11, C12, C13, C14, C15, C16, C17, C18, C19, C20, C21, C22, C23 +57 |
| 21 | 10k | Resistor_THT:R_Axial_DIN0207_L6.3mm_D2.5mm_P7.62mm_Horizontal | R1, R2, R3, R4, R10, R11, R12, R13, R16, R17, R18, R19, R20, R21, R22, R23 +5 |
| 21 | 74HC245 | Package_DIP:DIP-20_W7.62mm | U1, U2, U3, U4, U5, U6, U16, U17, U19, U23, U24, U46, U62, U63, U64, U65 +5 |
| 8 | 1u | Capacitor_THT:C_Radial_D5.0mm_H5.0mm_P2.00mm | C38, C71, C72, C73, C74, C80, C81, C85 |
| 8 | 74HC163 | Package_DIP:DIP-16_W7.62mm | U30, U31, U32, U33, U55, U56, U57, U58 |
| 8 | 74HC273 | Package_DIP:DIP-20_W7.62mm | U9, U10, U39, U42, U54, U61, U70, U71 |
| 8 | W29C020 | Package_DIP:DIP-32_W15.24mm | U26, U40, U44, U45, U47, U49, U52, U69 |
| 7 | 10u | Capacitor_THT:C_Radial_D5.0mm_H5.0mm_P2.00mm | C75, C76, C77, C78, C82, C83, C86 |
| 6 | Conn_02x20_Counter_Clockwise | Connector_PinSocket_2.54mm:PinSocket_2x20_P2.54mm_Vertical | J0, J1, J2, J3, J4, J5 |
| 5 | 74HC32 | Package_DIP:DIP-14_W7.62mm | U12, U15, U29, U48, U51 |
| 4 | 74HC193 | Package_DIP:DIP-16_W7.62mm | U34, U35, U36, U37 |
| 4 | MountingHole | MountingHole:MountingHole_3.2mm_M3 | H1, H2, H3, H4 |
| 3 | 74HC04 | Package_DIP:DIP-14_W7.62mm | U21, U27, U41 |
| 2 | 1k | Resistor_THT:R_Axial_DIN0207_L6.3mm_D2.5mm_P7.62mm_Horizontal | R14, R15 |
| 2 | 74HC08 | Package_DIP:DIP-14_W7.62mm | U20, U22 |
| 2 | 74HC138 | Package_DIP:DIP-16_W7.62mm | U50, U53 |
| 2 | 74HC151 | Package_DIP:DIP-16_W7.62mm | U14, U59 |
| 2 | 74HC283 | Package_DIP:DIP-16_W7.62mm | U13, U18 |
| 2 | 74LS157 | Package_DIP:DIP-16_W7.62mm | U72, U73 |
| 1 | 24512AK-15 | Package_DIP:DIP-32_W7.62mm | U38 |
| 1 | 4MHz | Oscillator:Oscillator_DIP-14 | X1 |
| 1 | 74HC11 | Package_DIP:DIP-14_W7.62mm | U25 |
| 1 | 74HC157 | Package_DIP:DIP-16_W7.62mm | U11 |
| 1 | 74HC4075 | Package_DIP:DIP-14_W7.62mm | U28 |
| 1 | 74HC74 | Package_DIP:DIP-14_W7.62mm | U60 |
| 1 | 74LS393 | Package_DIP:DIP-14_W7.62mm | U43 |
| 1 | SW_Push | Button_Switch_THT:SW_PUSH_6mm | SW1 |
| 1 | USB_B | Connector_USB:USB_B_OST_USB-B1HSxx_Horizontal | J9 |
Questions
How big is the Cpu PCB?
It measures 297 × 210 mm and has 2 copper layers, 1.6 mm thick.
What parts does the Cpu use?
197 parts, built around the 74HC245D, 74HC163D, 74HC273D and 74HC32D. 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 Cpu KiCad files?
From the tetrix450/masic-cpu repository on GitHub, at the commit this page was made from: the board is cpu.kicad_pcb and its schematic AC_reg.kicad_sch. PCBKit opens the board in the browser, with nothing to install.
Can I use the Cpu design in my own project?
Its repository publishes it under the MIT licence: you may reuse it on that licence's terms (keep the author's notice, and for a copyleft licence share your changes alike).
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