Low DOS duty cycle in Windows XP

[Guest]

Using the freeware program DIRECTIO.EXE (www.direct-io.com) I got my Quatech
SPP-100 PCMCIA to parallel port (IEEE-1284) card to write from the DOS
version of Quick Basic V4.5 running in the DOS emulation window of Windows XP
Home edition. The output was supposed to be continuous writes but was
actually only writing for 0.15 mS every 12 mS for a duty cycle of only
1.25%. Also, the output showed a lot of time jitter in the 12 mS repetition
rate. Is there any way for my QB program to obtain 100% duty cycle and
suppress the background activity of WinXP while the QB program is running?

 

[Bob I]

Maybe TameDOS. you can find the site on the net.

 

[V Green]

Using the freeware program DIRECTIO.EXE (www.direct-io.com) I got my Quatech
SPP-100 PCMCIA to parallel port (IEEE-1284) card to write from the DOS
version of Quick Basic V4.5 running in the DOS emulation window of Windows XP
Home edition. The output was supposed to be continuous writes but was
actually only writing for 0.15 mS every 12 mS for a duty cycle of only
1.25%. Also, the output showed a lot of time jitter in the 12 mS repetition
rate. Is there any way for my QB program to obtain 100% duty cycle and
suppress the background activity of WinXP while the QB program is running?

Depending on what you're trying to do, your solution may
be an analog one...not a software one.

Filter the outputs with small ceramic caps, trying different values
until you get what you want.

Don't know if this will work for you without specifics on what the logic
is driving.

A possible digital solution would be to use latching logic with
a settable time delay longer than the crap you're seeing.

 

[Guest]

The D0-D7 outputs along with SI\, AF\ and STRB\ (D25 pins 2-9, 17, 14, 1)
drive a Siemens SLO-2016 four digit 5x7 LED display with decoder. I am using
TAME-DOS to reduce the uP (Celeron M) useage. The duty cycle measurement was
made with an oscilloscope looking at D0-D7 with the SLO-2016 removed in a
continuous toggle mode QB V4.5 program. The several QB programs and SLO-2016
work OK together.