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Izzit true parallel port always output at windows startup?

 
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leesing2k3



Joined: 08 Nov 2005
Posts: 28

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Izzit true parallel port always output at windows startup?
PostPosted: Wed May 30, 2007 6:24 am     Reply with quote

Izzit true parallel port always output at windows startup?
Does anybody know which pin turn on during bootup? Or actually all of them will randomly output data during bootup?
Can I stop it through the bios or services in windows?

Thanks in advance.
PicFan



Joined: 01 Jan 2004
Posts: 11
Location: Indianapolis (Go Colts!)

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parallel port polling
PostPosted: Wed May 30, 2007 7:37 am     Reply with quote

If you're referring to Windows XP interfering with parallel port devices by occasionally polling the port, then check out the link below. It has worked for me in the past.

Regards,
PicFan

Link:
http://melabs.com/support/patches.htm#xppolling
Ttelmah
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PostPosted: Wed May 30, 2007 7:41 am     Reply with quote

The parallel port, has 12 pins that are outputs, and 5 that are inputs. This doesn't change (they are not programmable like on the PIC). However latter ports (ECP ports, rather than 'standard' parallel ports - SPP), have the ability to reprogram the main 8 pin directions.
EPP ports have the same basic hardware to the outside world, but add the ability to perform interrupt driven transfers.
All ports 'wake up' in 'SPP' mode.
The port direction is reversed, on ECP ports, by driving 'Fault' line low (called PeriphRequest on the ECP port). The host then acknowledges, by drving the 'INIT' pin (called 'ReverseRequest' on a ECP port) low.
Data is only valid on the port, when the 'DSTROBE' line pulses low. Your external hardware should only read or latch the data lines, when this happens.

Best Wishes
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