Xref: utzoo alt.msdos.programmer:1356 comp.sys.ibm.pc.programmer:266
Path: utzoo!attcan!uunet!mcsun!hp4nl!gufalet!bert
From: bert@gufalet.UUCP (Bert Bos)
Newsgroups: alt.msdos.programmer,comp.sys.ibm.pc.programmer
Subject: Re: idling in the interpreter
Message-ID: <783@gufalet.UUCP>
Date: 6 Mar 90 15:11:54 GMT
Followup-To: alt.msdos.programmer
Organization: Faculty of Arts, Groningen, The Netherlands
Lines: 9

In article <1990Mar2.022448.9490@usenet.ins.cwru.edu> trier@SCL.CWRU.Edu (Stephen Trier) writes:
>The first
>way, which is the most reliable, is to hook into interrupt 28h, sometimes
>known as the "DOS-Idle" interrupt.  MS-DOS calls this whenever it is waiting
>for some event, like a keystroke.  *Almost* all the MS-DOS functions are
>safe to use at this point.  (I'm not sure which ones aren't.)

According to a book I have (Michael Hyman; Memory resident utilities,
interrupts, and disk management with MS & PC DOS; MIS, 1987) it is
save to use DOS function calls with numbers above 12 at this point.