

Project GP8B
G_Processor8Bits a homemade without any microcontroller 8bits processor
- Size
- 133 × 93 mm
- Copper layers
- 4
- Thickness
- 1.6 mm
- Parts
- 110
- Nets
- 266
- Pads
- 1,036
- Tracks, vias
- 4,781, 457
- Pours
- 4
- Routed
- Yes
- KiCad
- KiCad 5 (file 20171130)
- Created
- 9 Jan 2020
- Updated
- 25 Jul 2024
Overview
Project GP8B is an open-source printed circuit board by JonathSpirit, from the JonathSpirit/GP8B repository on GitHub. It is a 4-layer board of 133 × 93 mm with 110 parts on 266 nets, routed with 4,781 tracks and 457 vias.
It is built around the 74AHCT244D, 74LVC1G34Z and 74AHC273D, with the 74AHC1G04SE, CD74AC238PW and 74AHC05T14 among its other parts. Its parts include 49 capacitors, 40 ICs, 7 resistors, 5 connectors and 2 diodes. It belongs with the retro computing and games boards and the FPGA and CPLD boards of this library.
Main components
1274AHCT244D
SOIC-20-300mil-40℃~+125℃ 2 4 4.5V~5.5V 5ns@5V,50pF 74AHCT 80uA 8mA 8mA Schmitt trigger Tri-State Unidirectional SOIC-20-300mil Buffers, Drivers, Receivers, Transceivers ROHSNexperiaBuffers, Drivers, Receivers, Transceivers74LVC1G34Z
SOT-553-5-40℃~+125℃ 1 1 1.65V~5.5V 1.6ns@5V,50pF 10uA 32mA 32mA 74LVC Power-off isolation Push-pull Unidirectional SOT-553-5 Buffers, Drivers, Receivers, Transceivers ROHSDiodes IncorporatedBuffers, Drivers, Receivers, Transceivers74AHC273D
SO-20-300mil-40℃~+125℃ 1 11ns@4.5V,50pF 165MHz 1ns 2V~5.5V 3ns 3pF 4uA 74AHC Series 8 8mA 8mA D-Type Reset Rising Edge SO-20-300mil Flip Flops ROHSNexperiaFlip Flops74AHC1G04SE
SOT-353-40℃~+125℃ 1 1 1.5V~3.85V 1.9V、2.9V、4.4V 1uA 2V~5.5V 500mV~1.65V 7.5ns@5V,50pF 74AHC 8mA 8mA Noise suppression function Schmitt trigger SOT-353 Inverters ROHSDiodes IncorporatedInvertersCD74AC238PW
TSSOP-16TSSOP-16 Analog Switches, Multiplexers ROHSTexas InstrumentsAnalog Switches, Multiplexers74AHC05T14
TSSOP-14-40℃~+125℃ 1 1.5V~3.85V 20uA 2V~5.5V 440mV 500mV~1.65V 6 7.5ns@5V,50pF 74AHC 8mA Schmitt trigger TSSOP-14 Inverters ROHSDiodes IncorporatedInverters74AHC08D
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 Gates74AHC138D
SO-16-40℃~+125℃ 2V~5.5V 4uA 6.3ns@5V,50pF 74AHC 8mA 8mA Decoder Single Supply SO-16 Signal Switches, Multiplexers, Decoders ROHSNexperiaSignal Switches / Encoders & Decoders / Multiplexers74AHC1G02GW
SOT-353-5-40℃~+125℃ 1 1.5V、2.1V、3.85V 1.9V、2.9V、3.94V、4.4V 100mV、360mV、550mV 2 2V~5.5V 40uA 500mV、900mV、1.65V 74AHC NOR Gate SOT-353-5 Logic Gates ROHSNexperiaLogic Gates74AHC1G08GW
SOT-353-40℃~+125℃ 1 1.5V~3.85V 1.9V~2V、2.9V~3V、3.7V~3.94V、4.4V~4.5V 100mV、360mV~550mV 10nA 2 2V~5.5V 500mV~1.65V 74AHC Series 9.5ns@3.3V,15pF AND Gate Overvoltage-tolerant input StandardCMOS SOT-353 Logic Gates ROHSMDDLogic Gates74AHC374D
SO-20-300mil-40℃~+125℃ 10.1ns@4.5V,50pF 185MHz 2V~5.5V 2ns 3ns 3pF 3uA 74AHC Series 8mA 8mA D-Type Rising Edge Tri-State SO-20-300mil Flip Flops ROHSNexperiaFlip Flops74AHCT273D
SO-20-300mil3pF 4.5V~5.5V 4uA 74AHCT Series 75MHz 8mA 8mA 9.2ns@5V,50pF D-Type Reset Rising Edge SO-20-300mil Flip Flops ROHSNexperiaFlip Flops
README
README.mdGP8B - GProcessor8Bits
Copyright (C) 2021 Guillaume Guillet
Licensed under CERN-OHL-W v2 or later
| This source describes Open Hardware and is licensed under the CERN-OHL-W v2 or later. |
| You may redistribute and modify this documentation and make products using it under the terms of the CERN-OHL-W v2 (https:/cern.ch/cern-ohl). This documentation is distributed WITHOUT ANY EXPRESS OR IMPLIED WARRANTY, INCLUDING OF MERCHANTABILITY, SATISFACTORY QUALITY AND FITNESS FOR A PARTICULAR PURPOSE. Please see the CERN-OHL-W v2 for applicable conditions. |
Made with Kicad
Description
G_Processor8Bits is a homemade, without any microcontroller, 8bits processor.

Stats
Block diagram
Instruction sets
GP8B follow CodeG_binary (revision 1)
8bits instuction is separated in 2 category :
-------------- Argument selection
|||
||| ---------- Opcode
||| |||||
000 000005bits for opcode :
OPCODE HEX NAME DESCRIPTION
xxx0’0000 0x00 BWRITE1_CLK Apply value to bus “write 1”.
xxx0’0001 0x01 BWRITE2_CLK Apply value to bus “write 2”.
xxx0’0010 0x02 BPCS_CLK Apply value to bus “peripheral CS”.
xxx0’0011 0x03 OPLEFT_CLK Apply value to the left operation.
xxx0’0100 0x04 OPRIGHT_CLK Apply value to the right operation.
xxx0’0101 0x05 OPCHOOSE_CLK Apply value for choosing the operation.
xxx0’0110 0x06 PERIPHERAL_CLK Send a clock pulse to the peripheral.
xxx0’0111 0x07 BJMPSRC1_CLK Apply value to bus “jump source 1”.
xxx0’1000 0x08 BJMPSRC2_CLK Apply value to bus “jump source 2”.
xxx0’1001 0x09 BJMPSRC3_CLK Apply value to bus “jump source 3”.
xxx0’1010 0x0A JMPSRC_CLK Jump to the address of “jump source”.
xxx0’1011 0x0B BRAMADD1_CLK Apply value to bus “RAM address 1”.
xxx0’1100 0x0C BRAMADD2_CLK Apply value to bus “RAM address 2”.
xxx0’1101 0x0D SPI_CLK Send a clock pulse for the SPI.
xxx0’1110 0x0E BCFG_SPI_CLK Apply value to the config bus SPI.
xxx0’1111 0x0F STICK Simple tick, do nothing (delay).
xxx1’0000 0x10 IF Conditional instruction.
xxx1’0001 0x11 IFNOT Conditional instruction inverted.
xxx1’0010 0x12 RAMW Write value to the actual address of the memory.
xxx1’0011 0x13 UOP Undefined operation.
xxx1’0100 0x14 UOP Undefined operation.
xxx1’0101 0x15 UOP Undefined operation.
xxx1’0110 0x16 UOP Undefined operation.
xxx1’0111 0x17 LTICK Long tick, do nothing (delay).3bits for argument selection :
OPCODE HEX NAME DESCRIPTION
000x’xxxx 0x00 SRCVALUE The value stored to the source.
001x’xxxx 0x20 BREAD1 The value of the read bus 1.
010x’xxxx 0x40 BREAD2 The value of the read bus 2.
011x’xxxx 0x60 OPRESULT The value of the operation result (ALU).
100x’xxxx 0x80 RAMVALUE The value of the processor memory.
101x’xxxx 0xA0 SPI The value of the SPI.
110x’xxxx 0xC0 EXT_1 External value 1.
111x’xxxx 0xE0 EXT_2 External value 2.Processor standard
This processor, follow the SPS1 standard
Compatibility
Compatible with all motherboard following the MOM1_SPS1 standard
Documents
Contributing / Questions
Please see Contributing file
Parts
110| Qty | Value | Footprint | References |
|---|---|---|---|
| 33 | 10nF | Capacitor_SMD:C_0805_2012Metric | C1, C2, C10, C11, C12, C13, C14, C15, C16, C17, C18, C19, C21, C22, C23, C25 +17 |
| 12 | 100nF | Capacitor_SMD:C_0805_2012Metric | C7, C9, C20, C24, C26, C28, C30, C31, C32, C36, C38, C39 |
| 9 | 74AHC273 | Package_SO:SOIC-20W_7.5x12.8mm_P1.27mm | U6, U24, U26, U27, U29, U31, U33, U35, U37 |
| 5 | 10k | Resistor_SMD:R_0805_2012Metric | R1, R2, R3, R6, R7 |
| 5 | 74AHCT244 | Package_SO:SOIC-20W_7.5x12.8mm_P1.27mm | U19, U20, U21, U22, U23 |
| 4 | 1uF | Capacitor_SMD:C_0805_2012Metric | C33, C40, C48, C49 |
| 4 | 74AHC1G04 | Package_TO_SOT_SMD:SOT-23-5 | U10, U12, U36, U39 |
| 4 | CD74AC238 | Package_SO:SOIC-16_3.9x9.9mm_P1.27mm | U9, U11, U13, U15 |
| 4 | MountingHole_3mm | MountingHole:MountingHole_3mm | H1, H2, H3, H4 |
| 3 | 74AHC05 | Package_SO:SOIC-14_3.9x8.7mm_P1.27mm | U1, U2, U5 |
| 2 | 74AHC08 | Package_SO:SOIC-14_3.9x8.7mm_P1.27mm | U14, U16 |
| 2 | 8x10k | Resistor_THT:R_Array_SIP9 | RN1, RN2 |
| 2 | GREEN_2.65V_2mA | LED_SMD:LED_1206_3216Metric | D1, D2 |
| 1 | 1k5 | Resistor_SMD:R_0805_2012Metric | R4 |
| 1 | 470E | Resistor_SMD:R_0805_2012Metric | R5 |
| 1 | 74AHC138 | Package_SO:SOIC-16W_5.3x10.2mm_P1.27mm | U17 |
| 1 | 74AHC1G02 | Package_TO_SOT_SMD:SOT-23-5 | U3 |
| 1 | 74AHC1G08 | Package_TO_SOT_SMD:SOT-23-5 | U4 |
| 1 | 74AHC374 | Package_SO:SOIC-20W_7.5x12.8mm_P1.27mm | U38 |
| 1 | 74AHCT273 | Package_SO:SOIC-20W_7.5x12.8mm_P1.27mm | U7 |
| 1 | 74AHCT595 | Package_SO:SOIC-16_3.9x9.9mm_P1.27mm | U25 |
| 1 | 74HC163 | Package_SO:SOIC-16_3.9x9.9mm_P1.27mm | U8 |
| 1 | 74HC166 | Package_SO:SOIC-16_3.9x9.9mm_P1.27mm | U18 |
| 1 | 74LVC1G34 | Package_TO_SOT_SMD:SOT-23-5 | U34 |
| 1 | ALU_JTAG | Connector_PinHeader_2.54mm:PinHeader_1x06_P2.54mm_Vertical | J1 |
| 1 | ALU_PINS | Connector_PinHeader_1.27mm:PinHeader_2x19_P1.27mm_Vertical | J5 |
| 1 | LOGO | QRCode:QRCode | G*** |
| 1 | MM1_5530843-2 | TE5530843-2:TE_5530843-2 | J3 |
| 1 | SN74AVC4T245D | Package_SO:SOIC-16_3.9x9.9mm_P1.27mm | U32 |
| 1 | SN74LVC8T245DW | Package_SO:SOIC-24W_7.5x15.4mm_P1.27mm | U30 |
| 1 | TE_Eurocard_96pole | Eurocard_5536475-1:Eurocard_5536475-1 | J2 |
| 1 | TPS7A0518PDBZR | Package_TO_SOT_SMD:SOT-23 | U28 |
| 1 | UnusedPins_Connector | Connector_PinHeader_1.27mm:PinHeader_2x15_P1.27mm_Vertical | J4 |
| 1 | XC2C256-VQ100 | Package_QFP:VQFP-100_14x14mm_P0.5mm | IC1 |
Questions
How big is the Project GP8B PCB?
It measures 133 × 93 mm and has 4 copper layers, 1.6 mm thick.
What parts does the Project GP8B use?
110 parts, built around the 74AHCT244D, 74LVC1G34Z, 74AHC273D and 74AHC1G04SE. 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 Project GP8B KiCad files?
From the JonathSpirit/GP8B repository on GitHub, at the commit this page was made from: the board is Project_GP8B.kicad_pcb. PCBKit opens the board in the browser, with nothing to install.
Can I use the Project GP8B design in my own project?
Its repository states no licence, so its author keeps all rights: ask JonathSpirit before reusing the design.
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