22 Jan
2008
22 Jan
'08
12:55 a.m.
Hello all,
I have an IBM PC, 5150, 16-64KB motherboard, that appears to be dead. Power
on produces no display or disk activity (even after a while), and no beeps
from the speaker (I tried a couple of speakers, so I
don't think it is a
speaker issue.
From what docs I found on the internet, the switches
are set up properly for
the machine's configuration...
I am pretty sure the motherboard is getting power. I checked at a RAM
socket, and all voltages were there, and well within specifications.
The problem is, I'm not sure where to go from here. I have NO schematics,
and haven't ever troubleshot a 5150 before.
I DO have a good meter, and a scope (and I know how to use it!)
What would be the first things to check?
Thanks for any help!!!
Rich B.
22 Jan
22 Jan
1:10 a.m.
Status of the RESET line and power_good signal? I don't know if the original
power supplies had a "power good" signal but I know that on newer machines,
if the power is out of tolerance, it won't POST.
On 1/21/08 7:55 PM, "Richard Beaudry" <richard.beaudry at gmail.com>
wrote:
Hello all,
I have an IBM PC, 5150, 16-64KB motherboard, that appears to be dead. Power
on produces no display or disk activity (even after a while), and no beeps
from the speaker (I tried a couple of speakers, so I don't think it is a
speaker issue.
Rich
--
Rich Cini
Collector of Classic Computers
Build Master and lead engineer, Altair32 Emulator
http://www.altair32.com
http://www.classiccmp.org/cini
From what docs I found on the internet, the
switches are set up properly for
the machine's configuration...
I am pretty sure the motherboard is getting power. I checked at a RAM
socket, and all voltages were there, and well within specifications.
The problem is, I'm not sure where to go from here. I have NO schematics,
and haven't ever troubleshot a 5150 before.
I DO have a good meter, and a scope (and I know how to use it!)
What would be the first things to check?
Thanks for any help!!!
Rich B. 
7:11 a.m.
Richard A. Cini wrote:
Status of the RESET line and power_good signal? I
don't know if the original
power supplies had a "power good" signal but I know that on newer machines,
if the power is out of tolerance, it won't POST.
<snip>
>
> I DO have a good meter, and a scope (and I know how to use it!)
>
>
Look and see if the processor is being held reset, or if there is
activity on the memory bus control lines. I don't have an 8088 pinout
handy, but there are bus state lines that should be pretty quiet if you
hold the processor reset. If they are rattleing then you got a lost
processor somewhere if the bios isn't posting.
Best would be a post card to decode outputs to port 80, but ... not on
your list.
The state lines are decoded by various parts of the hardware to
determine if the bus is doing memory operations, I/O or other
activities, so if they are going on a scope you can't infer much other
than enough circuitry is going to make the processor run around.
If the processor is not held reset, then there is not much to do but
probably try to find a post card. There isn't much what you have will
tell you as lots of things get signals, and you can't sync on much to
tell what is working and what isn't.
On the motherboard, the reset should be a short lived event. If it is
held down, you probably have a bad power supply. There is no reset
switch on an IBM PC, and other than the one applied by the power supply
at power good, and when you do control alt delete, you won't be seeing it.
Hope this gives some ideas.
Best things to find somewhere is the advanced diagnostics set, which has
lots of what you need, and a Post card, assuming the above don't suggest
something.
Jim
7:37 p.m.
Hello all,
I have an IBM PC, 5150, 16-64KB motherboard, that appears to be dead. Power
on produces no display or disk activity (even after a while), and no beeps
from the speaker (I tried a couple of speakers, so I don't think it is a
speaker issue.
The 5150 is a _very_ conventional 8088 design, there's really nothing at
all odd about it.
So, I'd start by checking the power-good line from the PSU. Then the
processor reset line (make sure the thing is not being held in the reset
state). Check the clock signals round the 8284 clock generator. Then
check for activity on the processor address and data pins and the ISA
slot address and data pins. Also check to see if the processor is HALTed,
IIRC some of the early POST tests will execute a HALT instruction if they
fail. I also seem to rememebr that on a 5150 or 5160, you can read out
the POST error code on one of the ports of the 8255, but I would have to
check the details.
You'll need the 8088, etc, data sheets to find those pins, but not the
schemaitcs of the board. I do have scheamtics at least of the 64K-256K
board (which I don't think is _that_ different in areas other than RAM),
but as ever I don't have any way of scanning them.
-tony
From what docs I found on the internet, the
switches are set up properly for
the machine's configuration...
I am pretty sure the motherboard is getting power. I checked at a RAM
socket, and all voltages were there, and well within specifications.
The problem is, I'm not sure where to go from here. I have NO schematics,
and haven't ever troubleshot a 5150 before.
I DO have a good meter, and a scope (and I know how to use it!)
What would be the first things to check? 
10:53 p.m.
--- Tony Duell <ard at p850ug1.demon.co.uk> wrote:
The 5150 is a _very_ conventional 8088 design,
there's really nothing at
all odd about it.
what examples could you give as a not so conventional
8088 board?
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23 Jan
23 Jan
9:04 a.m.
On Tuesday 22 January 2008 22:53:42 Chris M wrote:
--- Tony Duell <ard at p850ug1.demon.co.uk>
wrote:
Casio FZ sampler range?
Gordon
The 5150 is a _very_ conventional 8088 design,
there's really nothing at
all odd about it.
what examples could you give as a not so conventional
8088 board? 
5:09 p.m.
In article <573524.80932.qm at web61024.mail.yahoo.com>,
Chris M <chrism3667 at yahoo.com> writes:
--- Tony Duell <ard at p850ug1.demon.co.uk> wrote:
VT100 terminal? (OK, maybe it used an 8080, but you get the idea.)
--
"The Direct3D Graphics Pipeline" -- DirectX 9 draft available for download
<http://www.xmission.com/~legalize/book/download/index.html>
Legalize Adulthood! <http://blogs.xmission.com/legalize/>
The 5150 is a _very_ conventional 8088 design,
there's really nothing at
all odd about it.
what examples could you give as a not so conventional
8088 board? 
11:13 p.m.
On Tuesday 22 January 2008 17:53, Chris M wrote:
--- Tony Duell <ard at p850ug1.demon.co.uk>
wrote:
Well, my Tek scope has one in there, if I'm remembering right...
(Or was that an 8086? :-)
--
Member of the toughest, meanest, deadliest, most unrelenting -- and
ablest -- form of life in this section of space, ?a critter that can
be killed but can't be tamed. ?--Robert A. Heinlein, "The Puppet Masters"
-
Information is more dangerous than cannon to a society ruled by lies. --James
M Dakin
The 5150 is a _very_ conventional 8088 design,
there's really nothing at
all odd about it.
what examples could you give as a not so conventional 8088 board?
24 Jan
24 Jan
12:31 a.m.
--- "Roy J. Tellason" <rtellason at verizon.net> wrote:
On Tuesday 22 January 2008 17:53, Chris M wrote:
conventional 8088 board?
Well, my Tek scope has one in there, if I'm
remembering right...
(Or was that an 8086? :-)
What model is it Roy? There was a Tek analyzer thing
which in actuality was a peecee with a handle. IINM
model # was TC-2100 or something. Booted plain_jane
DOS too I think.
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--- Tony Duell <ard at p850ug1.demon.co.uk>
wrote:
> The 5150 is a _very_ conventional 8088 design,
there's really nothing at
all odd
about it.
what examples could you give as a not so
25 Jan
25 Jan
9:09 a.m.
On Wednesday 23 January 2008 19:31, Chris M wrote:
--- "Roy J. Tellason" <rtellason at
verizon.net> wrote:
It's a 2246.
On Tuesday 22 January 2008 17:53, Chris M wrote:
What model is it Roy? --- Tony Duell <ard at p850ug1.demon.co.uk>
wrote:
> The 5150 is a _very_ conventional 8088 design,
> there's really nothing at all odd about it.
> what examples could you give as a not so
> conventional 8088 board?
Well, my Tek scope has one in there, if I'm
remembering right...
(Or was that an 8086? :-) There was a Tek analyzer thing which in actuality was
a peecee with a
handle. IINM model # was TC-2100 or something. Booted plain_jane
DOS too I think.
I remember one time thinking that it might be a good idea to clean some of the
dust out of it, so I opened it up, and was rather surprised to find that
chip in there.
--
Member of the toughest, meanest, deadliest, most unrelenting -- and
ablest -- form of life in this section of space, ?a critter that can
be killed but can't be tamed. ?--Robert A. Heinlein, "The Puppet Masters"
-
Information is more dangerous than cannon to a society ruled by lies. --James
M Dakin
24 Jan
24 Jan
12:21 a.m.
--- Tony Duell <ard at p850ug1.demon.co.uk> wrote:
Depends on what I/you mean by 'unconventional'. But considerably less
conventional than the IBM 5150 are the Sirius/Victor 9000 (It uses 6522s
for I/O and has an 'interesting' video circuit), DEC Rainbow
(dual-processor with a Z80 and 8088, and the video chips from a VT100),
HP150-II (it has a CPU configured in minimum mode. But you can add an
8087 add-on card. Since the minimum mode doesn't support coprocessors,
the add-on card has an 8088 on it in maximum mode along with logic to
provide the minimum-mode signals to the rest of the machine. When that
card is fitted, the 8088 on the mainboard is disabled).
Not a computer, but somewhere I haev a 1200 baud modem that uses an 8088
as a DSP (A very odd choice...)
-tony
The 5150 is a _very_ conventional 8088 design,
there's really nothing at
all odd about it.
what examples could you give as a not so conventional
8088 board?
4:49 a.m.
On Wednesday 23 January 2008 19:21, Tony Duell wrote:
Not a computer, but somewhere I haev a 1200 baud modem
that uses an 8088
as a DSP (A very odd choice...)
Maybe not so odd when you consider what development tools used to cost for
some of the more uncommon processor chips compared with what was out there
for the 8088...
--
Member of the toughest, meanest, deadliest, most unrelenting -- and
ablest -- form of life in this section of space, ?a critter that can
be killed but can't be tamed. ?--Robert A. Heinlein, "The Puppet Masters"
-
Information is more dangerous than cannon to a society ruled by lies. --James
M Dakin
5:22 a.m.
IIRC, the 8086 is used as the brains in the Megatek graphics terminal.
--
"The Direct3D Graphics Pipeline" -- DirectX 9 draft available for download
<http://www.xmission.com/~legalize/book/download/index.html>
Legalize Adulthood! <http://blogs.xmission.com/legalize/>
6:33 a.m.
On Wed, Jan 23, 2008 at 11:49:21PM -0500, Roy J. Tellason wrote:
Maybe not so odd when you consider what development
tools used to cost for
some of the more uncommon processor chips compared with what was out there
for the 8088...
I have some of the hardware development tools that Software Results used
for making COMBOARDs - on the order of $10K and $20K new. We were able
to cheap-out on the software by writing our own 68K assembler for the VAX,
or that would have been several thousand more $$$ (this is in the same
timeframe as the 5150, BTW, 1981-1983 or so).
-ethan
--
Ethan Dicks, A-333-S Current South Pole Weather at 24-Jan-2008 at 06:29 Z
South Pole Station
PSC 468 Box 400 Temp -29.7 F (-34.3 C) Windchill -48.2 F (-44.6 C)
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Ethan.Dicks at usap.gov http://penguincentral.com/penguincentral.html
4:03 p.m.
--- "Roy J. Tellason" <rtellason at verizon.net> wrote:
On Wednesday 23 January 2008 19:21, Tony Duell
wrote:
Valid point, but I think he was just pointing out
that there were a number of better choices for that
job.
Tony, if you can dig out the make and model, I'd be
interested to hear.
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Not a computer, but somewhere I haev a 1200 baud
modem that uses an 8088
as a DSP (A very odd choice...)
Maybe not so odd when you consider what development
tools used to cost for
some of the more uncommon processor chips compared
with what was out there
for the 8088...
25 Jan
25 Jan
11:18 p.m.
wrote:
> > Not a computer, but somewhere I haev a 1200 baud
> modem that uses an 8088
> > as a DSP (A very odd choice...)
[...]
Tony, if you can dig out the make and model, I'd
be
interested to hear.
Better than that, I've found the modem (although not the PSU brick for it
yet...)
The front panel had a label stuck on it saying CASE 460/22. Under that
was the real maker's name, Concord Data Systems. I can't, alas, find any
Concord Data Systems model numebr on it.
Inside are 2 PCBs. The top one has the RS232 connector (DB25-S, of
course) and 4 8-way DIP switches on it. It contains an 8031, an OTP 2732
alongside it, lots of TTL, RS232 buffers, etc. I assume that processor
handles the command decoding, etc. The lower PCB contains the line
interface trasnformer and relay, lots of Op-amps and analogue bits,, an
8088, 8155, 8259, 8253, a 24 pin EPROM (I don't want to pull the label
off it), an ADC0804, etc. I am pretty sure that 8088 is doing some
DSP-like task.
-tony
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24 Jan
24 Jan
3:44 p.m.
--- Tony Duell <ard at p850ug1.demon.co.uk> wrote:
HP150-II (it has a CPU configured in minimum mode.
But you can add an
8087 add-on card. Since the minimum mode doesn't
support coprocessors,
the add-on card has an 8088 on it in maximum mode
along with logic to
provide the minimum-mode signals to the rest of the
machine. When that
card is fitted, the 8088 on the mainboard is
disabled).
Hmm just how is it disabled? Someone wanted to add an
8087 to a Peanut, and it made the most sense to plug a
board (w/a *new* 8088) into the old 8088 socket.
The 8088 can go into *offload mode* when it
encounters instructions intended for the 8087, but
that's probably not what you're talking about (at best
that would be considered intermittent *disabling*).
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25 Jan
25 Jan
11:12 p.m.
[HP150-II 8087 upgrade]
Hmm just how is it disabled? Someone wanted to add an
According to the Techref....
There's a D-type filp-flop ('74) driving the HOLD input on the mainboard
8088. When you plug the coprocessor card into its special connector, the
SET input of that flip-flop is grounded by the corprocessor board, thus
forcing the processor into the hold mode (normally used for DMA, of
course). There's also a link on the mainoard in series with the ALE
signal which you cut when you install the coprocessor board, since that
is one singal not tri-stated in hold mode.
8087 to a Peanut, and it made the most sense to plug
a
board (w/a *new* 8088) into the old 8088 socket.
If you're going to remove the original 8088, then there's no problem,
surely? As I menntioned, in the HP150-II, the cprocesor board plugs into
a special connecotor on the mainboard, not one of hte normal expanison
slots or anything like that.
-tony
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17 comments
9 participants
participants (9)
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ard＠p850ug1.demon.co.uk -
chrism3667＠yahoo.com -
ethan.dicks＠usap.gov -
gordonjcp＠gjcp.net -
jwstephens＠msm.umr.edu -
legalize＠xmission.com -
rcini＠optonline.net -
richard.beaudry＠gmail.com -
rtellason＠verizon.net