We help IT Professionals succeed at work.

Compaq Parallel Ports, Contura 4/25

RoadWarrior
RoadWarrior asked
on
Hi All,

I've been doing battle with an old Compaq Contura 4/25 recently. The parallel port behaves oddly. No diagnostic can pick it up, however I got it working with Laplink 5 after some experimenting.

In CMOS setup I have the options
Disable
LPT1 IRQ7
LPT2 IRQ7
LPT3 IRQ5

Now the only way I have got it working is to set it to LPT2 IRQ7 in CMOS and then in Laplink tell it it is LPT1 at address 378h, using polling, and although it can't self test and resetting the port sometimes locks up the computer, quitting out of the setup and attempting a connection works fine. I have a suspicion that when set to LPT1 in CMOS the port address will be 3BC, but laplink didn't seem to like that.

To all other diagnostics and system information programs I run, the port appears completely absent.

So, I am wondering if this is a "feature" of this computer, or the port is broken somehow. Compaq seems to provide some parallel port utilities and a BIOS flash for later conturas,  however, nothing seems to be specifically for the 4/25. In fact it worries me that some of their BIOSes seem to indicate compatibility at the bottom of the info page with more models than they could possibly work with. If anyone knows of a ROMpaq for this sytem I'd appreciate it greatly if it fixes this parallel port prob or adds a user definable HDD type.

Also at the moment I am particularly wondering if this is a "feature" whether Linux is known to have problems with it. As I would much like to network under Slackware with a PLIP cable.

thanks much in advance for your responses,

Road Warrior
Comment
Watch Question

rid

Commented:
rid

Commented:
rid

Commented:

Author

Commented:
rid

Commented:
Very inspiring and thought-provoking thread, this... I tried to say something about the old graphics adapter/parallel port interface of the IBM PC; I think they used the 3BC address. Compaq, unhelpful as usual, doesn't want to disclose the real I/O addresses but calls the options "LPT1", "LPT2" instead. If that is the case, I think the "LPT2" variety corresponds to the modern concept of the first parallel port at 378 (or whatever) and IRQ7. There may be a problem adjusting some software to this situation.
Regards
/RID

Author

Commented:
Thanks for the comment rid, I had heard that the original PC par ports used 3BC and Compaq held onto using that address through the AT and beyond, I don't think the software has particular problems with the address, it was just a bit hard to confirm on this machine with the port refusing to detect at all. I have a Zenith laptop with 3BC as the port address for LPT1 and that seem to detect and work fine.

I swapped the HDD out before I fully investigated the parallel port problem, replacing it with one that has MSDOS 6.22 on instead of the one that had IBMDOS on. I'm wondering if in those system files IBMBIOS.SYS etc, whether there was any kludges for the compaq par port, but I recall not seeing the par port in the diag I ran before I changed out the drive, so I think the problem still existed then.

Road Warrior
Commented:
According to one source, BIOS will scan four places for a parallel port register: 3BC, 378, 278 and 2BC in that order. Ports will be designated LPT1, -2 etc in the order they are found. One of the system files, msdos.sys in the case of DOS 6 (I think) is responsible for translating software calls to BIOS calls (like accepting PRN for output to LPT1). I suppose some confusion may result if this original plan isn't adhered to, like using "LPT1" label for 378 even if it happens to be the second parallel port on the system...
/RID

Author

Commented:
Didn't get anywhere with this, now a dead issue, other fish to fry and such,  points to rid for moral support
rid

Commented:
Thanks :)

I think I'll put that on my "office" door...
"General Helpdesk and Moral Support"

Cheers
/RID

Explore More ContentExplore courses, solutions, and other research materials related to this topic.