Assembly Language Programs

The most convenient way of writing and running assembly language programs on the ZX81 computer is to use an assembler program to carry out the translation from assembly language to machine code. A suitable assembler program is ZXAS. If an assembler is not available, programs can be translated manually; this process is known as hand assembly and is described in detail in Appendix B. After the program has been translated into machine code it can be run by the computer and any errors in the program can be found and corrected. This is a more difficult process with assembly language programs than it is with BASIC programs. The process can be made easier by the use of a program which helps you to examine what is happening inside the computer while your program is running. A program of this type is called a debugger and for the ZX81 the program ZXDB performs this invaluable task.