GENS3 is a powerful and easy-to-use Z80 assembler which is very close to the standard Zilog assembler in definition. Unlike many other assemblers available for microcomputers, GENS3 is an extensive, professional piece of software and you are urged to study the following sections, together with the example in Appendix 3, very carefully before attempting to use the assembler. If you are a complete novice, work through Appendix 3 first.
GENS3 is roughly 9K bytes in length, once relocated, and uses its own internal stack so that it is a self-contained piece of software. It contains its own integral line editor which places the text file immediately after the GENS3 code while the assembler’s symbol table is created after the textfile. Thus when loading GENS3 you must allow enough room to include the assembler itself and the maximum symbol table and text size that you are likely to use in the current session. It will often be convenient, therefore, to load GENS3 into low memory.
To load GENS3 proceed as follows:
Place the supplied tape in your cassette recorder, type:
LOAD "" CODE xxxxxand press PLAY on the recorder – where xxxxx is the decimal address at which you want GENS3 to run.
Once you have loade the GENS3 code into the computer you may enter the assembler by RANDOMIZE USR xxxxx where xxxxx is the address at which you loaded the assembler code. If at any subsequent time you wish to re-enter the assembler then you should execute the address xxxxx + 56 for a cold start (destroying any text) or address xxxxx for a warm start (preserving any previously created textfile).
For example, say you want to load GENS3 so that it executes from address 26000 decimal – proceed as follows:
LOAD "" CODE 26000
RANDOMIZE USR 26000To re-enter the assembler use RANDOMIZE USR 26056 for a cold start and RANDOMIZE USR 26000 for a warm start.
Once you have entered GENS3, you will be prompted with a ‘>’ sign, the editor’s command prompt – consult Section 3 for how to enter and edit text and Section 2 for what to enter.