Commodore User

Commodore 16 Exposed
By Melbourne House
Commodore 16

Published in Commodore User #21

Commodore 16 Exposed

The third offering from Melbourne House for the C16, Commodore 16 Exposed, is described on the cover as 'an encyclopaedia of solutions which begins with Basic programming and takes the reader through to machine language'. Well, I don't know about an encyclopaedia of solutions, but they've got the chronology roughly right.

Introductory chapters are devoted to Basic programming taking you right through from elementary one-line programs to more complex stuff involving loops, subroutines and arithmetic expressions. There's also a comprehensive explanation of variables, arrays and arithmetic and Boolean operators.

From there we move on to more advanced Basic techniques, including how to save memory and increase program speed and how to scan the keyboard. This section also contains some useful machine-code subroutines (don't panic fledglings, they're loaded into memory by a simple Basic program) such as OLD, which retrieves a program wiped out by a NEW instruction.

A chapter on graphics and sound deals quite well with the latter, including an interrupt driven program to read and play a table of notes. Graphics, however, get scant attention, the only item of interest being an explanation of the way the screen is organised.

After an unnecessary chatper on peripherals (their workings are much better deal with in the manuals), there follow several chapters on machine-code, some good, others not. All the important stuff is included - binary and hex, addressing techniques, memory maps and so on. Some of the more complicated topics, like indexed addressing, could have done with more coverage. Not only were techniques inadequately explained, but no examples were given as to how they might be used.

This book is a bit of a mixed bag. Whilst it contains a lot of useful reference material like the chapters on TEDMON, the KERNAL, and memory organisations, a good sized chunk of the other material is duplicated in the manual. A bad case of the C16 overexposed. You may, therefore, find it hard to justify the £6.95 price tag.

Ken McMahon