mos120

This repo contains fixed copies of the annotated BBC MOS 1.20 disassembly from http://mdfs.net/Docs/Comp/BBC/OS1-20/ as well as scripts and additional files that permit automated conversion into ca65 syntax.

Building requires two invocations of ./bin/convert.sh and then one of ./bin/compile.sh.

The two passes of convert.sh are necessary to be able to convert both forward and backwards code references into labels - the first pass finds the addresses that are targets of references, and the second writes those labels into the source.

Fixes to the original disassembly files include:

• convert all files to NL terminated
• split FC00 file at FF00 so I can use the real ROM contents in place of JIM/FRED/SHEILA
• ensured all hex constants are prefixed accordingly
• replaced a few addresses with computed offsets from labelled addresses
• removed some duplicate chunks of code left over from the file split
• inserted a couple of missing instructions
• fixed character case errors in some string constants
• resolved various other minor typos