Very Computer

by **Gary Hennig** » Tue, 11 Feb 1992 02:02:00

First I guess I should ask if anyone knows for sure that the PS/2 Model 55sx
has a 16550 UART in it's serial port. My understanding was that all PS/2's
including and above the Model 50 had a 16550 built in. If this is true why
doesn't OS/2 recognize it? I do:
MODE COM1:BUFFER=ON
or
MODE COM1:ENHANCED=ON
and OS/2 tells me that both BUFFER= and ENHANCED= are invalid for my serial
device! I think I remember reading that the first 16550's had some
problems, is there a way to distinguish the bad 16550's from the good ones?
Has anyone else gotten their m55sx to use the 16550? If it is indeed a bad
16550 will IBM replace it? I've had the machine for about 1.5 years so the
warranty is no longer there.

Any info greatly appreciated,
--
Gary Hennigan
+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=++=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=
+= PhD Student, Computational Electromagnetics | Member: Utilitarian +=
+= New Mexico State University | .signature club +=
+= Phone: (505)646-4808 ----------------------+=

by **Jeff Altm** » Thu, 13 Feb 1992 05:37:48

>First I guess I should ask if anyone knows for sure that the PS/2 Model 55sx
>has a 16550 UART in it's serial port. My understanding was that all PS/2's
>including and above the Model 50 had a 16550 built in.

The first 4 months or so of 55sx's have original 16550 not 16550A[NF]
implementations. The 16550 contained a defective buffer and would not
switch into FIFO mode.

Quote:>I think I remember reading that the first 16550's had some
>problems, is there a way to distinguish the bad 16550's from the good ones?
>Has anyone else gotten their m55sx to use the 16550?

HAven't been able to try because 1.167f will not work with my SCSI drive.

Quote:>If it is indeed a bad
>16550 will IBM replace it? I've had the machine for about 1.5 years so the
>warranty is no longer there.

I am an IBM Technical Advisor. As such I am supposed to be provided with
direct service info from IBM. When I inquired about this with IBM National
Dealer Support I was told that IBM did not consider the use of a 16550 instead
of the 16550ANF a defect, even though the FIFO did not work. Therefore,
IBM would not replace the planar board for FREE. The cost was somewhere over
$400 if I wanted to send mine in for a swap. Two to three weeks with shipping
time.

And no, it is not possible to replace the chip yourself.

>Any info greatly appreciated,
>--
>Gary Hennigan
>+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=++=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=
>+= PhD Student, Computational Electromagnetics | Member: Utilitarian +=
>+= New Mexico State University | .signature club +=
>+= Phone: (505)646-4808 ----------------------+=

--
- Jeff | Altmania Productions |================================|

by **Jason Campbe** » Thu, 13 Feb 1992 11:16:12

>>First I guess I should ask if anyone knows for sure that the PS/2 Model 55sx
>>has a 16550 UART in it's serial port. My understanding was that all PS/2's
>>including and above the Model 50 had a 16550 built in.

>The first 4 months or so of 55sx's have original 16550 not 16550A[NF]
>implementations. The 16550 contained a defective buffer and would not
>switch into FIFO mode.

>HAven't been able to try because 1.167f will not work with my SCSI drive.

It seems to work on my 55sx. I get a status of "buffer=on" from the mode
display, but I have no real way to confirm it, as that machine has only
a 2400 baud modem.

Anyone know a way to check for sure?

Jason
--
Jason Campbell | Stanford University | "Loose _wait_ now, ask me how!"

:-):-):-):-):-):-):-):-):-):-):-):-):-):-):-) just in case I forgot a few.

Very Computer

16550, PS/2 m55sx and OS/2 6.167f?

16550, PS/2 m55sx and OS/2 6.167f?

16550, PS/2 m55sx and OS/2 6.167f?

16550, PS/2 m55sx and OS/2 6.167f?