MorseBoard 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 make

Go to the folder and run make

cd src/uartboard
make

Flash 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