Relocating Loader (RLC) Format

What is RLC

The Model 100 use an 8085 CPU. This CPU does not support position independent machine code, at least in any traditional sense.

Also, the Model 100 has no built-in support for transferring binary machine language files over the serial port.

Presumably for these reasons, the authors of programs residing in the M100SIG on Compuserve created the RLC format. RLC is a representation of an 8085 machine language program that is relocatable and 7-bit clean.

Format

Overview

RLC is an ASCII base-16 representation of an 8085 machine language program. Unlike traditional hexadecimal, however, it uses the ASCII characters

0123456789:;<=>?

It starts with a header, followed by the body, and ending with a checksum. Whitespace is permitted, and most RLC files seem to keep the data less than 128 bytes per line.

Header

The first line starts with (in ASCII format) the number of bytes in the RLC file, followed by the offset within the image to the entry point.

The numeric values are space separated. For example, here is the first line of an RLC file coding for a 7387 byte image, whose entry point is the first byte of the image.

7387  0

It is not clear whether the header needs to be on its own line. It is also unclear whether the first line needs to start with a space.