ART100@psuvm.psu.edu (Andy Tefft) (10/08/90)
I've been thinking a screen blanker would be kinda neat for those of us without GS's. It would be rather easy to write as a basic.system command I guess, but what could be done about having it work outside of basic.system? Any ideas?
alfter@uns-helios.nevada.edu (SCOTT ALFTER) (10/08/90)
Re: 8-bit screen blanker.
One possibility would be to take over the code in ProDOS 8 that works with the
/RAM disk and replace it with an interrupt daemon that acts on "heartbeats"
from, say, a clock card. Big problems there are (1) there are a whole bunch of
different clock cards (tho' the Thunderclock is the standard), (2) this does
nothing for the IIc folks who don't have slots, and (3) some programs like to
turn off interrupts.
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Scott Alfter _/_
/ v \ Apple II:
Internet: alfter@uns-helios.nevada.edu ( ( the power to be your best!
GEnie: S.ALFTER \_^_/toddpw@tybalt.caltech.edu (Todd P. Whitesel) (10/08/90)
An even simpler way would be to replace the RDKEY routine so that the screen saver only cuts in when the computer is waiting for a key. Programs which read the keyboard themselves (of which there are lots) would foil this scheme but it is the only one I can think of that doesn't require interrupts. Todd Whitesel toddpw @ tybalt.caltech.edu
flee@gnh-applesauce.cts.com (FRANK LEE) (10/13/90)
I've written a screen blanker for DOS 3.3. It occupies page 3, but I've re-assembled it once to allow it to hide itself right under $9D00. The limitations of my pgm are as follows: o Will work only when the computer is expecting user input. o Best environment would be when programming in BASIC or when in the Monitor. This is mainly due to the fact that Apples don't have features like a clock-tick interrupt, like they do on IBMs. Also, the machine must be in text mode when it runs. If you have an Apple IIe or II+, a hardware solution may be better. Connect some type of relay to the annunciator outputs to turn the video signal on and off. Some custom circuitry will be needed. My routine doesn't really blank the screen, but it provides an animated display of a block cursor bouncing around a blank screen. INET: flee@gnh-applesauce.cts.com UUCP: crash!pnet01!gnh-applesauce!flee ARPA: crash!pnet01!gnh-applesauce!flee@nosc.mil