Nascom News­let­ter

When all that is required is for the program to wait until Enter or Newline is pressed, you only need the following line&nsbp:

10 IF INP(0) AND 2 THEN 10

This will loop until Enter is pressed.

… and a naughty way.

The Basic interpreter must be modified if a genuine INKEY function is required. The Microsoft Basic that the Nascom uses was adapted from a program written in 8080 machine code. The 8080 doesn’t have an ‘IN r,(C)’ instruction, so a small skeleton subroutine is used instead. The subroutine looks like this:

This resides in RAM, as can be seen from the addresses. If DBH is changed to DFH, a Nas-Sys RST SCAL will be executed. The monitor subroutine called being dependent on the number passed by the INP() function. Any subroutine that doesn’t require an argument can be used. The useful routines and their numbers are:

Example

Line 30 is required when using SCAL IN as this routine returns values greater than 128 when no key is pressed.

Well, you now have no excuse for ever being a USR again! The two ways of detecting a key press from Basic are so incredibly obvious, I can’t imagine why no one else has ever thought of then before!