Machine language simplified

The lack of an author’s name on Machine Language Programming Made Simple For Your Sinclair ZX-80 and ZX-81 indicates it may have been prepared by a committee. We decided the author was probably a comic art character used throughout the book to enliven the text. Dressed in a court jester’s outfit, wearing a CPU chip T-shirt, the arty little character is helpful for the reader. The jester frowns, smiles or looks confused to indicate the density of the text,

A disturbing number of typographical errors are sprinkled through the text. This is probably a result of the book being printed in Hong Kong, where proofreaders are not known for their mastery of English. However, these typos are so apparent that their presence should not keep you from purchasing the book.

The authors (or committee) get off to a good start in the first chapter with listings of advantages and disadvantages of machine language programming. The chapter ends with an excellent sentence summarizing machine language programming:

“It’s hard, it’s frustrating, it’s inconvenient, but it’s a wonderful practice and gives you a great insight into the way computers work.”

The book is written for the typical ZX81 or Timex 1000 user — someone with limited experience with a computer system. Next, the function of the CPU is explained, followed by information on computer counting and numbering systems used in machine coding, both binary and hexadecimal (HEX).

One problem with the book is the term “location.” Sometimes this is referred to as a single byte of memory having 8 bits, or as the address (which is two bytes, 16 bits) of the data base.

Next, the court jester shows how data is manipulated, using his hands, feet, fingers and boxes for storage. Then, the ZX80 instruction set is introduced in about a dozen groups containing several short program routines.

The final third of the 160-page book concerns programming in machine code and how it can be loaded into the ZX80, ZX81 and Timex 1000. For short routines hand assembly could be used. However, the longer routines would need an assembler-editor program to do the major coding.

The lengthy program at the end of the book is called “Checkers” in the United States and Canada, and “Draughts” in England.

The utility of the book is diminished by lack of a comprehensive index. Perhaps after a thorough study of the contents, a reader will know where to look for help with a specific program.