DOS ain't dead - How many parallel and serial port can I use in DOS ?

Damien

06.01.2013, 16:05

How many parallel and serial port can I use in DOS ? (Developers)

Hello,

I've been wondering how many parallel ports I can use in my Dos programs. I mean, considering the fact that I have many PCI slots with many "add parallel port card".

I have seen several times the number of 3 or 4 ports, but I'm not sure of this.
And What is the nature of this limitation? Is the the same for all x86-based PCs? Does it depend on the hardware, the bios, the operating system ?

In other way, have you ever managed to use 4 parallel ports at the same time ?

And of course, same question about serial ports... is there a limitation of 4 ports? Or can we go further with more serial PCI cards ?

Thanks

RayeR

CZ,
06.01.2013, 21:32

@ Damien

How many parallel and serial port can I use in DOS ?

Post reply

DOS/BIOS mostly covers support up to 2 LPT and 4 COM ports. I think that you may have as many ports you want/fit in the PC but you must be able to assign them different IO address. If you use a PCI card PnP will do it for you. Then you have to write your own handling of such card by your own.
Most of DOS programs rely on fixed legacy IO address like e.g. LPT1 have always base at 378h. But If you have some PCI card you will probably got assigned some high IO base like E000h. At work I have one PCI-E arapter from Axago with 2*COM + 1 LPT and it do like that. Even there was a DOS utility that should set IO bases on legacy addresses it doesn't work (it needs some PCI-PCI bridge reconfiguration for proper IO forwardion which probably the utility cannot do). So I gave up port under DOS. Under windows XP COM ports works fine, LPT for mostly too but for some stupid apps (greeting for ST micro code monkeys) looking directly at legacy address it didn't work too.

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DOS gives me freedom to unlimited HW access.

marcov

07.01.2013, 18:29

@ RayeR

How many parallel and serial port can I use in DOS ?

Post reply

> So I gave up port under DOS. Under windows
> XP COM ports works fine, LPT for mostly too but for some stupid apps
> (greeting for ST micro code monkeys) looking directly at legacy address it
> didn't work too.

XP is no problem. I have a system with 10 comports under Windows XP. (one card with 6 comports, one with 4)

Easiest is if you buy cards with moschip (MCS) 9845/65 (PCI) or 9922 (pciex).

Many companies like Sweex and trust have cards with these chips, and they are generally very well supported by various windows versions (including 64-bit Windows including win8) and *nix.

IIRC the PCI chips (98x5) came with dos setup utils. The only pciex brand that I have (MCS9922 based) doesn't seem to come with them though.

RayeR

CZ,
08.01.2013, 03:49

@ marcov

How many parallel and serial port can I use in DOS ?

Post reply

> Easiest is if you buy cards with moschip (MCS) 9845/65 (PCI) or 9922
> (pciex).

I have one with Moschip 9901, here's some info (sry only CZ)
http://rayer.g6.cz/hardware/mbisa.htm#AXAGO-COM-LPT

BTW I was also thinking about one special kind of HW port extension - lot of new mobo has TPM slot for trusted shit but in fact it's LPC. It may be possible to connect some full featured SpuerIO chip and bring back COM, LPT and FDC. It would need also some initialization code but not impossible. I saw similar solution from Shuttle.

---
DOS gives me freedom to unlimited HW access.

Damien

09.01.2013, 12:58

@ marcov

How many parallel and serial port can I use in DOS ?

Post reply

>
> XP is no problem. I have a system with 10 comports under Windows XP. (one
> card with 6 comports, one with 4)
>
> Easiest is if you buy cards with moschip (MCS) 9845/65 (PCI) or 9922
> (pciex).
>

OK so if I understand, there is no precise rule of how many serial and parallel ports I can get under DOS, the best thing to do is to try!?

At the present time I already use a PCI card with moschip which gives serial and parallel ports at adresses like E000 or E400. It seems to work well so I will just try to put more PCI-cards!

I'll try to give a feedback if I find something interesting.

RayeR

CZ,
09.01.2013, 13:40

@ Damien

How many parallel and serial port can I use in DOS ?

Post reply

> At the present time I already use a PCI card with moschip which gives
> serial and parallel ports at adresses like E000 or E400. It seems to work
> well so I will just try to put more PCI-cards!
>
> I'll try to give a feedback if I find something interesting.

You can write a driver, that will probe PCI bus (directly or via PCI bios) for such UART chips, then read theirs IO base and then handle as normal serial port. Also you need to solve shared interrupts some way. But you cannot learn old apps to use this ports.

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DOS gives me freedom to unlimited HW access.