2 layers127 × 127 mm
Morseboard-8088
ifilot/morseboard-8088
Single board computer designed around the 8088 processor
61 parts
2 layers172.1 × 108 mm
Mb88-testboard
ifilot/morseboard-8088Single board computer designed around the 8088 processor
- Size
- 172.1 × 108 mm
- Copper layers
- 2
- Thickness
- 1.6 mm
- Parts
- 81
- Nets
- 129
- Pads
- 414
- Tracks, vias
- 1,369, 66
- Pours
- 2
- Routed
- Yes
- KiCad
- KiCad 9.0 (file 20241229)
- Created
- 7 May 2025
- Updated
- 11 Jul 2026
Overview
Mb88-testboard is an open-source printed circuit board by ifilot, from the ifilot/morseboard-8088 repository on GitHub. It is a 2-layer board of 172.1 × 108 mm with 81 parts on 129 nets, routed with 1,369 tracks and 66 vias.
It is built around the 74HCT245, 74HCT573D and 74HCT00D, with the 74HCT02D, 74HCT138D and 74HCT273D among its other parts. Its parts include 41 diodes, 15 capacitors, 10 ICs, 4 resistors and 3 switches. It belongs with the computers and single-board computers boards of this library.
Main components
7
74HCT245
DIP-20-40℃~+85℃ 28ns@4.5V 4.5V~5.5V 6mA 6mA 74HCT 8 8uA Bidirectional TTL-compatible CMOS Tri-State DIP-20 Buffers, Drivers, Receivers, Transceivers ROHSWuxi I-core Elec74 Series
74HCT573D
SO-20-300mil-40℃~+125℃ 13ns 20ns 4.5V~5.5V 74HCT 8 8uA 9ns D Latch Tri-State SOIC-20 Latches ROHSNexperiaLatches
74HCT00D
SO-14-40℃~+125℃ 100mV、400mV 12ns@4.5V,50pF 2 2V 3.7V、4.4V 4 4.5V~5.5V 40uA 4mA 4mA 74HCT Series 800mV NAND Gate Overvoltage-tolerant input TTL Compatible CMOS SO-14 Logic Gates ROHSNexperiaLogic Gates74HCT02D
SO-14-40℃~+125℃ 19ns@4.5V,50pF 2 2V 2uA 3.7V 4 4.5V~5.5V 400mV 4mA 4mA 74HCT Series 800mV NOR Gate Overvoltage-tolerant input SOIC-14 Logic Gates ROHSNexperiaGates
74HCT138D
SO-16-40℃~+125℃ 160uA 20ns@4.5V,50pF 3/8 4.5V~5.5V 4mA 4mA 74HCT Decoder Single Supply SOIC-16 Signal Switches, Multiplexers, Decoders ROHSNexperiaSignal Switches / Encoders & Decoders / Multiplexers74HCT273D
SOIC-20-300mil-40℃~+125℃ 12ns 3.5pF 30ns@4.5V,50pF 36MHz 3ns 4.5V~5.5V 4mA 5.2mA 74HCT Series 8 8uA D-Type Reset Rising Edge SOIC-20-300mil Flip Flops ROHSNexperiaFlip Flops
AS6C4008-55PCN
PDIP-320℃~+70℃ 2.7V~5.5V 30mA 4Mbit 4uA 55ns Parallel Port (Parallel) PDIP-32 SRAM ROHSAlliance MemorySRAM
README
README.mdMorseBoard 8088
A single-board computer built around the Intel 8088 microprocessor.
The name MorseBoard is a tribute to Stephen P. Morse, the lead architect of the Intel 8086 microprocessor — the foundational design on which the 8088 is based. His work played a pivotal role in shaping early x86 computing.
Board Layout
The 8088’s 20-bit address bus allows access to 1 MiB of addressable memory, divided into:
- 512 KiB of RAM in the lower memory segment
- 512 KiB of ROM in the upper memory segment
Address/data multiplexing is handled using 74HCT573 latches.
Serial communication is enabled via a TL16C550 UART and a MAX232 level
shifter.
Eight LEDs are connected to I/O port 0x00 using a 74HCT273 register,
providing simple visual output.
A 7.3728 MHz CAN oscillator is used to drive both the 8088 and the serial interface. Because of this frequency, you must use the 8088-2 variant, which supports higher clock rates.
Design Files
- PCB layout:
pcb/morseboard-8088 - Firmware source:
src/uartboard
Assembly is done using the NASM assembler, available via
common Linux package managers (e.g., Ubuntu). A Makefile is provided for
convenience.
To flash the ROM, the recommended tool is the PICO-SST39SF0x0 programmer.
Assembly instructions
To assemble the source code of the ROM, follow the instructions below. Make sure you have installed the proper toolchain.
sudo apt install nasm makeGo to the folder and run make
cd src/uartboard
makeFlash the resulting rom.bin onto the SST39SF040 chip.
Test Board
In addition to the full-featured board with UART support, a CPU test board
is available under pcb/cpu-testboard. This board is designed to validate 8088
chips — particularly useful given the unreliability of some second-hand CPUs,
since they are no longer in production.
License
Hardware
The hardware design files for the MorseBoard 8088 are licensed under the
CERN Open Hardware License v2 - Strongly Reciprocal (CERN-OHL-S-2.0).
You are free to use, modify, and distribute the hardware under the terms of this
license.
More info: CERN-OHL-S-2.0
Software
The firmware and software source code is licensed under the
GNU General Public License v3.0 (GPLv3).
You are free to use, share, and modify the code as long as derivative works
remain under the same license.
More info: GPLv3 License
Parts
81| Qty | Value | Footprint | References |
|---|---|---|---|
| 40 | LED | LED_THT:LED_D5.0mm | D1, D2, D10, D11, D12, D13, D14, D15, D16, D17, D18, D19, D20, D21, D22, D23 +24 |
| 13 | 100nF | Capacitor_THT:C_Disc_D5.0mm_W2.5mm_P5.00mm | C3, C4, C5, C6, C7, C8, C9, C10, C11, C12, C13, C14, C15 |
| 5 | 510 | Resistor_THT:R_Array_SIP9 | RN1, RN2, RN3, RN4, RN5 |
| 2 | 10k | Resistor_THT:R_Axial_DIN0207_L6.3mm_D2.5mm_P7.62mm_Horizontal | R7, R8 |
| 2 | 74HCT573 | Package_DIP:DIP-20_W7.62mm_Socket | U2, U3 |
| 1 | 100k | Resistor_THT:R_Axial_DIN0207_L6.3mm_D2.5mm_P7.62mm_Horizontal | R1 |
| 1 | 10uF | Capacitor_THT:CP_Radial_D5.0mm_P2.50mm | C2 |
| 1 | 220uF | Capacitor_THT:CP_Radial_D6.3mm_P2.50mm | C1 |
| 1 | 560 | Resistor_THT:R_Axial_DIN0207_L6.3mm_D2.5mm_P7.62mm_Horizontal | R2 |
| 1 | 74HCT00 | Package_DIP:DIP-14_W7.62mm_Socket | U8 |
| 1 | 74HCT02 | Package_DIP:DIP-14_W7.62mm_Socket | U7 |
| 1 | 74HCT138 | Package_DIP:DIP-16_W7.62mm_Socket | U6 |
| 1 | 74HCT245 | Package_DIP:DIP-20_W7.62mm_Socket | U4 |
| 1 | 74HCT273 | Package_DIP:DIP-20_W7.62mm_Socket | U10 |
| 1 | 8088 | Package_DIP:DIP-40_W15.24mm_Socket | U1 |
| 1 | AS6C4008-55PCN | Package_DIP:DIP-32_W15.24mm_Socket | U9 |
| 1 | LOGO | components:morseboard-logo | G*** |
| 1 | NMI | Button_Switch_THT:SW_PUSH_6mm | SW4 |
| 1 | POWER | LED_THT:LED_D5.0mm | D9 |
| 1 | RES | Button_Switch_THT:SW_PUSH_6mm | SW3 |
| 1 | SST39SF040 | Socket:DIP_Socket-32_W11.9_W12.7_W15.24_W17.78_W18.5_3M_232-1285-00-0602J | U5 |
| 1 | SW_SPDT | components:power_switch | SW1 |
| 1 | TCXO-14 | Oscillator:Oscillator_DIP-14 | X1 |
| 1 | USB_B | Connector_USB:USB_B_OST_USB-B1HSxx_Horizontal | J1 |
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Questions
How big is the Mb88-testboard PCB?
It measures 172.1 × 108 mm and has 2 copper layers, 1.6 mm thick.
What parts does the Mb88-testboard use?
81 parts, built around the 74HCT245, 74HCT573D, 74HCT00D and 74HCT02D. 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 Mb88-testboard KiCad files?
From the ifilot/morseboard-8088 repository on GitHub, at the commit this page was made from: the board is pcb/cpu-testboard/mb88-testboard.kicad_pcb and its schematic pcb/cpu-testboard/mb88-testboard.kicad_sch. PCBKit opens the board in the browser, with nothing to install.
Can I use the Mb88-testboard design in my own project?
Its repository states no licence, so its author keeps all rights: ask ifilot before reusing the design.