This file describes the program Ssaver which is an event-driven screen saver for the 8 bit BBC micros using a 6845 cathode ray tube controller.

Instructions

If not accessing the utility via the Utilities Menu, type *RUN U.SSAVER at the BASIC prompt.

The program will at first not appear to have done anything. This is because the screen saver is simply loaded, and not configured yet!

You can configure the screen saver to restore the screen on the occurrence of any event (see your User Guide under *FX14 and *FX13 for details of event numbers).

Next, at the prompt, type CHAIN"U.SSTEST"

This will run a really simple program demonstrating the use of a new OSWord call which sets up the screen saver to your requirements. In this particular case, it sets a delay of about ten seconds, restoring the screen with a keypress.

The technical details of the OSWord have been defined as follows:

Entry A=&E0
      X and Y point to a 12 byte parameter block in memory
      XY+00 = 10
      XY+01 = 0
      XY+02 = Two byte delay in 50ths of a second
      XY+04 = 1st event number to unblank the screen
        :
      XY+0B = 8th event number that will unblank the screen
Exit  Parameter block unchanged

Note that if you don't want eight different events to restore the screen, simply pad the other values with a duplicate of one you've used already:

      XY+00 = 10
      XY+01 = 0
      XY+02 = 5000 (about 100 seconds)
      XY+04 = 2 (screen comes back when a key is pressed)
      XY+05 = 7 (screen comes back when a serial port error occurs)
      XY+05 = 7 (padding)
      XY+05 = 7 (padding)
      XY+05 = 7 (padding)
      XY+05 = 7 (padding)
      XY+05 = 7 (padding)
      XY+05 = 7 (padding)

Known Problems/Future Enhancements

No known problems.

History