GEOS KERNAL v2.0 - commented source code for GEOS 2.0 C128 with cleanups and optimizations
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README.md

GEOS KERNAL v2.0 - commented source code of GEOS 128

by Maciej 'YTM/Elysium' Witkowiak ytm@elysium.pl 2002-2014

#DESCRIPTION This archive contains FULL source code of GEOS KERNAL v2.0, english version. It is identical to original in critical points but the code is revised, optimized, reorganized and first steps towards modularizing are made.

#DISCLAIMER This package comes from full disassembling of GEOS KERNAL. I did it for my own pleasure and purposes in my spare time. It is meant for customizing the code and not for making big bucks on it. If you want to use GEOS KERNAL generated from these sources you need to have an original copy of GEOS, because you can do nothing without DeskTop, applications and so.

Although I have throughly tested it I cannot guarantee that it will work on any hardware configuration and with any applications.

#REQUIREMENTS The only tool required is ACME (version at least 0.07). It may be obtained from: http://sourceforge.net/projects/acme-crossass/

#ASSEMBLY Just issue command:

acme geos.tas

#CUSTOMIZATION

Look into inc/equ.inc file - there are many true/false defines, you are free to change them. But read the comments. You can compile-in input and disk drivers so right after boot you will have your drivers (and you can boot from 1571/81 without any problems). In case that input driver is compiled into KERNAL you have to delete all input driver files from boot disk, because DeskTop will try to load the first one overriding compiled driver.

#THE SOURCES

Source code is organized in a specific way. You can browse through it easier by using some keypoints:

##1) Labels All global labels are identical to those from geosSym and geosMac files. All OS_JUMPTAB functions are preceded with '_'. For example EnterDeskTop is placed in jumptab as:

EnterDeskTop		JMP _EnterDeskTop
(...)
_EnterDeskTOp		; code for handling this function

All other labels are meant to descript the purpose of a subroutine. It was not always possible, so you may find some UNK_xxx, xxxHelp_xx and lots of procedures with the same name but different number e.g. Font11, Font12 etc. In current version all labels are global and these which should be local are made by abbreviation of the subroutine with a number on its end. In future releases it will be fixed and named ACME !zone(s) will be used.

##2) Indentation This goes like that:

		[tab2]				[tab6]
Label		LDA #0				;$xxxx

CPU opcodes are always on 1st or 2nd tab. If it is 1st tab position, it means that the purpose of current/called subroutine/memory location is unknown. Comments are always on 6th tab position. The source is full of ;$xxxx comments. It is relict from disassembling the KERNAL - those marks helped me a lot when debugging. Currently the values there are wrong because code is optimized and reorganized. They will be removed in future releases.