6502 For The Beginner

BBC Micro Utilities - a tape-based package - consists of a monitor and several example routines from a fairly good book on 6502 assembler programming on the BBC by Bruce Smith (Shira). This cassette is probably intended as an extra teaching guide to accompany it.

The package as a whole certainly does not come into the all-singing all-dancing bracket, although the initial loading screen did play a bar from Close Encounters with Lord Shiva kicking away out of time in the background.

A major problem with Beemon - the monitor utility - is it is written in Basic, and as such occupies a large chunk of memory which may be needed for other purposes such as your own machine code program.

Still, it features a disassembler, memory modifier, single-stepper, dump routine, memory move and fill routine. and a cassette interface which is primarily a method of loading and saving your machine code programs.

The monitor runs in Mode 7 only, and is wholly menu-driven. Most of the features functioned adequately, though not to a level which 1 would have thought necessary to be a proper training tool. For example, the stepper is not capable of displaying the instructions as it steps along a piece of code.

Also any errors in your machine code program will usually mean that you will have to come out of Bcemon. load and correct your program, assemble it again, save the binary code to tape, and then reload Beemon for another try.

Even worse, the instructions do not give any guide to the addresses where you may load your machine without corrupting Becmon itself.

The rest of the tape is padded out with example routines, such as word and multibyte addition and subtraction, hex and binary conversions, usage of some simple key input routines and so on. Nothing dramatic here except that they may save some typing for people following Bruce's book.

In conclusion, this package is strictly low-cost beginner's application stuff and it is adequate in that respect. People wishing to take up 6502 programming further will still need to get a proper ROM-based monitor eventually.

Chris Chan