jrasm - Assembler for JR-200 Download View on GitHub

An assembler of Motorola 6800 MPU with features useful to program for JR-200.

What’s This?

This is an assembler of Motorola 6800 MPU, an 8bit CPU designed by Motorola in 1974. And it has some features that I expect are useful to program for JR-200, a micro computer made by Panasonic in 1983.

This project has been inspired by JR-200 emulator VJR-200 developed by FIND, which is available here.

Installation

A Windows executable is available here. Expand its content in a directory that is included in PATH environment variable.

It has been tested in Windows 10 64bit.

Let’s Try It

Consider the following source file named helloworld.asm:

        .ORG    0x1000
loop:
        LDX     [ptr_src]
        LDAA    [X]
        BEQ     done
        INX
        STX     [ptr_src]
        LDX     [ptr_dst]
        STAA    [X]
        INX
        STX     [ptr_dst]
        BRA     loop
done:
        RTS
ptr_src:
        .DW     hello_world
ptr_dst:
        .DW     0xc100 + 9 + 20 * 0x20
hello_world:
        .DB     "Hello, world!", 0

To assemble it, just launch jrasm with the source file name.

> jrasm helloworld.asm

This creates a CJR file named helloworld.cjr. You can load the CJR file to a JR-200 emulator or convert it into a WAV file that is fed to a real machine through a cassette recorder interface.

After loading it, you can call the program using JR-200 BASIC like follows:

U=USR($1000)

You see “Hello, world!” on the screen? Congratulations!

Specifying -D options prints the produced binary data with corresponding assembler codes to the standard output.

> jrasm -D helloworld.asm

The result is:

                   .ORG 0x1000
loop:
    1000 FE 10 17  LDX  [ptr_src]
    1003 A6 00     LDAA [X]
    1005 27 0F     BEQ  done
    1007 08        INX 
    1008 FF 10 17  STX  [ptr_src]
    100B FE 10 19  LDX  [ptr_dst]
    100E A7 00     STAA [X]
    1010 08        INX 
    1011 FF 10 19  STX  [ptr_dst]
    1014 20 EA     BRA  loop
done:
    1016 39        RTS 
ptr_src:
    1017 10 1B     .DW  hello_world
ptr_dst:
    1019 C3 89     .DW  0xc100+9+20*0x20
hello_world:
    101B 48 65     .DB  "Hello, world!",0
    101D 6C 6C   
    101F 6F 2C   
    1021 20 77   
    1023 6F 72   
    1025 6C 64   
    1027 21 00   