Introduction
============

This repository contains the original source code for Acorn BBC Basic
128 version 1.11.

The structure of the repository is as follows:

    original_sources.zip

              - a copy of the original BBC Basic 128 source files,
                with the original <cr> line endings, and with the
                original (but broken) broken version of Bas10

    dfs/      - disk images in DFS (ssd and dsd) formats;
                these are generated by the make_disk_images.sh script
                which uses SWEH's Perl mmb_utils.

    src/      - the BBC Basic 128 source files (with various build fixes,
                including the reconstruction of Bas10 from a disassembly).

    tools/    - binaries for MASM (both DFS and non-DFS versions)

Assembling the OS Source Code
=============================

An "ordinary" 6502 Co Processor is needed to assemble the BBC Basic
128 sources.

The source code is in Acorn MASM format, and a copy of the "Normal"
version of MASM is included in the disk images.

Using DFS:
==========

(or MMFS)

The disk organization on DFS involves two disk images:
- drive 0: Tools (MASM) and Working files
- drive 2: BBC Basic 128 sources

In the dfs/ directory are following versions:

Two seperate single sided disk images:
    ssd/AcornBas128_disk0.ssd
    ssd/AcornBas128_disk2.ssd

One double-sided disk image:
    dsd/AcornBas128_disk02.dsd

Transfer one of these disk image sets onto your physical hardware.

To assemble the sources, you just need to boot disk 0 (it contains an
appropriate !BOOT file)

The Basic 128 binaries are generated on DRIVE 0 (two files):

$.Bas128
    (this has a MD5SUM of 9e65b6df380914531d574600c0a6ae7d)
$.BasObj
    (this has a MD5SUM of 601f3e505266a3d6eaa7634558c330b9)

Note: This version (1.11) is later than the commonly available version
(1.10); the differences are very minor:

33c33
< 00000200  6f 66 74 20 31 39 38 35  2c 20 56 31 2e 31 30 00  |oft 1985, V1.10.|
---
> 00000200  6f 66 74 20 31 39 38 35  2c 20 56 31 2e 31 31 00  |oft 1985, V1.11.|
866c866
< 00003610  85 2d 20 60 7a a0 00 a6  38 f0 0c 20 9d 7e d9 00  |.- `z...8.. .~..|
---
> 00003610  85 2d 20 60 7a a0 00 a6  38 f0 0c 20 a1 7e d9 00  |.- `z...8.. .~..|

This is a 1-byte change to code in INSTR, presumably fixing a rare bug
as INSTR is not obviously broken in 1.10.

Acknowledgements:
=================

Many thanks to Paul Fellows (ex Acornsoft) for discovering these
long-lost sources and making them available to the Acorn community.