Hello, Charles.  Thanks for your response as we were trying to help
Wayne C. by giving our best advice.

 JH> You say your 486 had a fast UART and the Pentium only has
 JH> an 8250? I'm surprised. I think before I tried doing a UART
 JH> chip-swap (if I could even _find_ a separate UART chip),
 JH> I'd consider looking for a serial card with 16550 UART(s),
 JH> and disabling the mainboard Serial ports.

 CA> If the machine had an internal modem orginally I can imagine
 CA> how they decided the serial ports did not need a true 16550A. I
 CA> would go with an internal modem myself even though it is nice
 CA> to have an external around for testing etc. of other systems.

Possible.  Wayne's 486 was a Packard Bell, and I worked with one of
those which had some sort of a modem-on-a-daughterboard 14.4 modem.  A
PITA it was, as removing the card and jumpering the board to disable
still wouldn't free up that COM port so that a modem card could use it.
This one was a 486SX, and I wouldn't be surprised if it had 16450
equivalent UARTS incorporated into the I/O part of the onboard chipset
in lieu of a separate UART chip.

 JH> In any event, if what the Pentium board has is only 8250 or
 JH> compatible/emulated, I think no need to hurry to buy an
 JH> external 56K serial modem, as TBOMK the 8250 won't support
 JH> that speed. Corrections welcomed, if I'm wrong.

BTW, I didn't really suspect his pentium board had an 8250. Turns out
Wayne says the 8250 is on one of his 486 boards, per his subsequent
post.

 CA> Seems like 'baiting' here to me but ...

You?  Baiting?  Noooooooooooo!

 CA> At the speed of that CPU I would guess at the very least the
 CA> UARTs are 16450s or even 16550s (no 'A')? This would be shabby
 CA> business practices IMO but I can imagine some manuf did try to
 CA> sneak the plain 16550s through to save that 'nickel' they
 CA> squeeze so very tightly. :-\

If so, probably for price competition in the consumer market.

 CA> AFAIK the 8250, 16450, and 16550 (no 'A') are more or less the
 CA> same in terms of performance.
 CA> MSD.EXE from Wayne's W31 OS should tell him what they are?
 CA> I've tested both the 8250 and 16450 and they will support 57600
 CA> using a null modem cable between the serial ports and GSZ as
 CA> the application software doing the transfers with zero resends.

Well, a direct connection via null modem cable is one thing, but as you
say - -

 CA> If, as is the prevailing wisdom, a locked 115200 was attempted
 CA> then all bets are off as these UARTs might error out frequently
 CA> which means any compression to achieve random speed 'bursts'
 CA> wouldn't happen for the 56k modem which is never really at 56k
 CA> anyhow. We all know that the FCC has limited us to 53k at most
 CA> and typical connects are 40-44k to the ISP using POTS lines?

 CA> When using a browser these speed bursts are handy for the HTML
 CA> (text) portion of the webpages, for downloading files not so.
 CA> Most application software files are compressed into an archive
 CA> and maintain a certain average speed thoughout the entire
 CA> download.

 CA> This slight variation when browsing may not be significant?

Unclear to me- are you saying that my advice to Wayne that 8250 UART
chip won't support 56K external modem (knowing he intends to use Windows
and/or Linux and surf the web) wasn't good advice, and you think the 56K
external modem would work OK for him in that application?

But all of our advice on this is pretty much moot now, since Wayne is so
tickled with the Celeron 433 and Pentium machines he now has.  My guess
is that he'll never make it back to working with the Packard Bell 486
mainboards.

 CA> Judging by server stats from my music webpage almost 50% of all
 CA> who frequent that webpage are on DSL connects which is another
 CA> excuse for neglecting to put in 16550As? Serial ports are
 CA> dropping in significance lately.

Your music webpage caters to the carriage trade? (aka the rich)? :-).

Both my kids have DSL now, and it sure is _fast_ compared to my setup.
I keep waiting for the price of the DSL service to come down, but it
doesn't seem to be coming down much.

Yep, with so many peripherals going to USB now, and with mouse on a PS/2
port, and I suspect a very small % of users wanting an external modem,
it may not be long before onboard serial ports are eliminated, and
those who want them would have to put in an expansion card, as we
did for so many years.  Heck, they could do away with parallel port too,
and use USB for the printer.  Seems to me the way the industry is going,
with USB moving to standard printer interface, and parallel port maybe
moving to an "option" which might be eliminated before much longer.

- - - JimH.
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