From: davidg@aegis.or.jp (Dave McLane)
Newsgroups: comp.dcom.modems
Subject: Re: Can I upgrade a 16450 uart to a 16550a?
Date: 11 Jan 93 09:56:42 GMT

jim@n5ial.mythical.com (Jim Graham) writes:

>In article <3602@aegis.or.jp> davidg@aegis.or.jp writes:

>> [I wrote]:

>>> In article <1993Jan7.152939.28987@wam.umd.edu> joel@wam.umd.edu writes:
>>
>>>> I was almost sure Dell would have put a good uart in the
>>>> machine, but it turns out it's only a 16450.
>>>>
>>>> Is it possible to upgrade the 16450 to a 16550a?
>>
>>> yes.  they are pin-compatible, provided that you replace it with the
>>> same package...e.g., replace DIP (16550AN or 16550AFN) with DIP, etc.

>> But in the case of the Dell 325D, the "16450" isn't a separate chip;
>> it's part of VLSI which is soldered in place. In such cases you have
>> to add a card with the new chips on it.

>if that's the case, you're right.  however, the original post said that
>the chip in question is a 16450, not a 16450 clone on a multi-port card.
>that's what I responded to.

Uhhh, but that's the problem, the original poster said it was a 16450
but this wasn't confirmed by Dell:

  | From: joel@wam.umd.edu (Joel M. Hoffman)
  | Newsgroups: comp.dcom.modems
  | Subject: Can I upgrade a 16450 uart to a 16550a?
  | Message-ID: <1993Jan7.152939.28987@wam.umd.edu>
  | Date: 7 Jan 93 15:29:39 GMT
  | Sender: usenet@wam.umd.edu (USENET News system)
  | Organization: University of Maryland, College Park
  |
  | I just purchased a high speed modem (14.4K from Boca) for my Dell
  | 325D.  I was almost sure Dell would have put a good uart in the
  | machine, but it turns out it's only a 16450.  Naturally, I'm losing
  | char.s with high-speed transfers, especially with a loaded machine
  | (I'm running Linux --- a Unix clone).
  | 
  | Is it possible to upgrade the 16450 to a 16550a?  (I assume that will
  | help the problem; correct me if I'm wrong.)  
  | 
  | [I tried asking the representative a Dell, but, when he answer my
  | question of "What kind of uart is in the machine" with "You have a
  | VLSI chip," I gave up.]
  | 
  | Thanks in advance.
  | 
  | -Joel


>> Sorry, but the ignorance is on your side. The Dell 325D does in fact
>> have a VLSI. I would say the trouble with the person at Dell was they
>> assumed you were computer literate :-)

>computer literate?  let's see, the original poster says that the serial
>port has a 16450 UART in it, and wants to know if it can be replaced
>with a 16550.  notice that he doesn't say the chip is a clone of a
>16450, along with a bunch of other stuff rolled in --- he says it's a
>16450, period.  if you look at a chip that's labelled xx16450 (where
>xx are the vendor's initials), well, it seems pretty straightforward to
>me that it's somebody's 16450....

Well, this is part of the mystery, isn't it. The original poster
says he has a 16450 but he doesn't say how he knows that. When he
talks to Dell they tell him he has a VLSI but he doesn't understand
that so he's stuck with the idea that his Dell 325D has a 16450 UART
in it. But I've already been through this as I have a Dell 325D and
when I looked inside to find the UART all I could see were funny
looking things hidden under the power supply. It turns out they
looked funny because they were VLSI's not UARTS. Live and learn....

>based on that information (which appears to have been incorrect to begin
>with), my statements were correct --- it can be directly replaced with a
>16550.  of course, that assumes that the app-notes and specs from
>National Semiconductor are correct.  :-)  and it also assumes that I
>wasn't dreaming when I replaced a few 16450s with 16550s a while back.

Unfortunately you only responded to part of the original post. The
clue was the part where Dell says it has a VLSI.

>btw, just as a bit of nit-picking, replacing one chip with another
>isn't so much a question of being computer literate as it is a matter
>of being HARDWARE literate.  just so happens that some of us are both
>(after all, when designing and/or interfacing with the hardware, it's
>often hard these days to draw the line between where the hardware stops
>and the software begins).  but this question (``Is it possible to
>upgrade the 16450 to a 16550a?'') is purely a hardware question, not
>a software question.

But we aren't discussing how to replace one chip with another, we're
talking about what kind of UART the Dell 325D has and this boils
down to being computer literate ('computer' including both hardware
and software) enough to know what a "VLSI" is. Or if you don't know,
finding out.

But instead, the original poster gets the idea that it's a 16450
(how, he doesn't say) so he calls Dell and they tell him that a Dell
325D has a VLSI. He doesn't understand (and doesn't ask) but he
gives up and come onto the net asking his original question. 

Maybe I shouldn't have bothered to suggest a solution but just
asked, "How do you know the Dell 325D has a 16450 UART? Have you
taken it apart and physically located the chip? If not, please do
before asking how you can change one...."

Dave

--
Dave McLane 
JUNET: davidg@aegis.or.jp (ONLY within Japan: post otherwise)
Nagaokakyoshi, Kyoto Japan Tel: +81-75-951-1168 Fax: +81-75-957-1087

 

Newsgroups: comp.dcom.modems,comp.dcom.fax