Actually .... I disassembled the print.exe of dos 6.0 today, just to satisfy my curiosity (there is nothing much on the net about old technologie) and print seems to use one of the oldest multitasking mechanisms around (in dos and windows) the msdos multitask interrupt. and this is timer driven peter -----Original Message----- From: Dr. Imre Bartfai To: PICLIST@MITVMA.MIT.EDU Date: Wednesday, May 19, 1999 10:34 AM Subject: Re: Multitasking without interrupt ? >Hi, >I must retire. I checked and it seems really so, that PRINT itself does >not use the IRQ of the printer. The following statement has deceived me: >"IRQ 7 [ ... means] data request on LPT1" from Helppc. It seemed logical >for me... >Sorry again. >Imre > >> >> On Tue, 18 May 1999, Peter van Hoof wrote: >> >> > The dos print spooler polls the parallel port on the timer interrupt, no >> > interrupt from the printer is needed >> > >> > -timer interrupt jumps to hooked service routine (about 18 times a second) >> > -printer status check >> > -if printer buffer empty send new characters >> > -if printing done unhook timer interrupt >> > -jump to original timer service routine >> > -original timer service routine returns controll to dos till next timer >> > interrupt >> > >> > Peter pvh@vertonet.com >> > >> > >> > -----Original Message----- >> > From: Sean Breheny >> > To: PICLIST@MITVMA.MIT.EDU >> > Date: Tuesday, May 18, 1999 8:42 PM >> > Subject: Re: Multitasking without interrupt ? >> > >> > >> > >Hi Imre, >> > > >> > >How does it work on PC's without a printer IRQ? I thought I had used it on >> > >ones that probably didn't have a printer interrupt. >> > > >> > >Sean >> > > >> > >At 11:32 AM 5/17/99 +0200, you wrote: >> > >>Hi, >> > >>only as a small remark: the DOS print spooler (I do not know whether >> > >>another ones...) is working on an interrupt basis, as the printer tells >> > >>with an IT if the data has been printed, so asks for new data. There is no >> > >>time slicing. >> > >>Imre >> > >> >> > >> >> > > >> > >| >> > >| Sean Breheny >> > >| Amateur Radio Callsign: KA3YXM >> > >| Electrical Engineering Student >> > >\--------------=---------------- >> > >Save lives, please look at http://www.all.org >> > >Personal page: http://www.people.cornell.edu/pages/shb7 >> > >mailto:shb7@cornell.edu ICQ #: 3329174 >> > >> > >> >>