Assembly example programs for the 5500FP, a 24-trit balanced-ternary RISC processor.

These programs are intended to be assembled with the CrossASM macro-assembler (see https://github.com/MOS5500/CrossASM_5500FP) and executed on the 5500FP development board.

• *.asm — example programs at the top level
• include/ — header files with constant definitions, brought into the source via the .INCLUDE directive
• COMMON/ — accessory code shared by most of the examples

The repository contains a collection of example programs, each exercising a different aspect of the processor. The filenames are descriptive of what is tested. Further examples may be added over time.

Suggested starting points for a first contact with the system:

• Test_OutSingleChar.asm — output of a single character on the serial line
• Test_OutString_2.asm — output of a null-terminated string on the serial line

These two examples are minimal, produce immediately visible output on the host terminal, and are the recommended way to verify a correct bring-up of the board before exploring the other examples.

The CrossASM cross-assembler is distributed as a Windows executable in the CrossASM_5500FP repository. It runs natively under Windows.

Copy the .asm source file you want to assemble, together with any required files from include/ and COMMON/, into the same directory as CrossASM.exe.

Run CrossASM.exe. The program takes no command-line arguments; it opens an interactive menu.

From the menu:

1. Option 1 — Set the source file. Type the name of the .asm file to assemble, without the extension (for example: Test_OutSingleChar).

2. Option 3 — Assemble the program.

3. Option 4 — Write the assembled program to an SD card. CrossASM will prompt for:

   • the drive letter of the SD card on the host PC;
   • the storage mode: Raw (1) or FileSystem (2).

   Select FileSystem (2). This is the format expected by the FirstBootLoader stored in the GargantuRAM ROM. The Raw mode is reserved for low-level use cases and is not needed during normal operation.

A successful write produces the confirmation message:

The program was written correctly to the SDCard <letter>:

Warning — Writing to the SD card is a destructive operation that erases all existing data on the card. CrossASM displays an explicit confirmation prompt before proceeding.

Once CrossASM has written the program to the SD card:

1. Eject the SD card from the host PC.
2. Insert the SD card into the SD slot of the GargantuRAM board, accessible on the rear of the 5500FP development unit.
3. Power-cycle (or reset) the board.

On boot, the FirstBootLoader resident in the GargantuRAM ROM reads the program from the SD card and starts execution.

The 5500FP development board exposes two USB-UART adaptors based on the CP2102 chip. To observe the output of an example, connect the host PC to serial port 2 (the default output channel) and open a terminal emulator (PuTTY, minicom, or equivalent) with the following parameters:

The CP2102 chip is natively recognised on Windows, Linux, and macOS without additional driver installation.

The 5500FP processor and its system documentation are archived on Zenodo: doi:10.5281/zenodo.18881738.