INMC 80 News


October–December 1981 · Issue 5

Page 62 of 71


Automatic entry of several Machine Code programs

By A.J.Fry

The Generate command in Nas-Sys 1 automatically loads and starts a program. However if the ‘Execute’ address which is given to start the program is merely the address of the DF 5B monitor return instruction in that program (There is not a DF 5B?!! – go and read the manual on how to end a program) then the only action will be to return to monitor control.

A second program may now be entered automatically by using the same process. The second program need not contain a DF 5B provided the address of the DF 5B in the first program is given as the ‘Execute’ address when recording the second program using the Generate command. Subsequent programs may be similarly entered. Thus a cassette tape may be prepared which will load any number of programs (or a main program and several subroutines) without the need to enter a single command via the keyboard. No program will be executed until the command is given either manually or as the execute address of the final program/​subroutine which is loaded.

The individual programs or subroutines need not occupy adjacent blocks of memory and no ‘unoccupied’ memory need be recorded on the tape as would be necessary if the whole group were widespread through memory and were then saved as a single program.

Page 62 of 71