Messages in this thread |  | | Date | Thu, 8 Aug 1996 13:34:51 -0400 | From | "Theodore Y. Ts'o" <> | Subject | Re: serial ports |
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Date: Thu, 8 Aug 1996 13:05:04 -0400 (EDT) From: "Andrew E. Mileski" <aem@nic.ott.hookup.net>
I was refering to 2 and 4 port cards like the generic ones you can pick up at most computer parts desks. I also carefully chose my words so that what I wrote could be applied to _ANY_ brand.
You said:
>Every 2, 4, and 8 multi-uart card I've ever used or seen has the >extra logic required for electrically correct ISA interrupt sharing.
I have **never** seen a multi-uart card using the COM1/2/3/4 addresses that has **ever** had the extra logic required for doing electrically correct ISA interrupt sharing. And I say this with 10 years of experience in the PC/ISA "architecture" (if you can call it that without abusing the term "architecture" too much).
The reason why I reacted so angrily to you note is because I'm tired of hearing people complain about why they've tried to use COM1 and COM3 on some cheap $10 (in your words) "generic ones that you can pick up at most computer parts desks", AND THEY DON'T WORK. I'm tired of sending the same e-mail messages over and over and over again.
If you use a cheap $20 generic one, in my experience the chances you will get the interrupt sharing to work is zero. If you get a properly designed AST FourPort, or a Usenet serial card, or a Bocaboard card, which are designed to be able to share interrupts, then you will win. But you have to pay more for a card that's designed correctly.
You _CAN_ share any interrupt. It takes extra hardware. A board that supports this _CAN_ share IRQ4 between COM1 and COM3. _BUT_ not all boards have this capability.
Interesting. You said in your original message that *all* boards have this capability, and this is simply not correct. If your message causes novices to have hope that they can actually share COM1 and COM3 using a "generic COM 1/2/3/4 serial port", you will have just increased the amount of work I have to do --- because I feel I have a responsibility to help out newbies who send me e-mail asking for help --- and I don't have the time to deal with this nonsense.
Please don't spew mis-information, while sounding authoratative. Those people who sound like they know what they are talking about really annoy those of us who do. :-)
- Ted
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