17 Dec
2016
17 Dec
'16
9:14 p.m.
I was happy to find a IBM XT for a good price at the scrapyard today in
very nice condition. It is missing the hard drive, but i have plenty of
those, the controller was still inside.
I had a little issue getting video working at first, i do not have a 9
pin cga monitor laying around, thankfully i found a 16 bit isa card that
also works in an 8 bit slot.
The machine starts up and runs its memory test, however it gives a 301
error. System halts and says press f1 to continue, but no luck, keyboard
is unresponsive. I have tried about 10 different keyboards on the
machine, including some model M keyboards with a ps2 adapter with no luck.
A quick search does turn up that 301 is a keyboard related error, but i
am not sure what exactly the issue is.
Am i doing something stupid here or am i looking at the possibility of
something being wrong with the machine?
--Devin
17 Dec
17 Dec
9:33 p.m.
On 12/17/16 9:14 PM, Devin wrote:
I was happy to find a IBM XT for a good price at the
scrapyard today
in very nice condition. It is missing the hard drive, but i have
plenty of those, the controller was still inside.
I had a little issue getting video working at first, i do not have a 9
pin cga monitor laying around, thankfully i found a 16 bit isa card
that also works in an 8 bit slot.
The machine starts up and runs its memory test, however it gives a 301
error. System halts and says press f1 to continue, but no luck,
keyboard is unresponsive. I have tried about 10 different keyboards on
the machine, including some model M keyboards with a ps2 adapter with
no luck.
Model M keyboards are AT-style keyboards, they won't work with an XT
(different protocol). You will need to find a PC/XT compatible keyboard
to use.
- Josh
A quick search does turn up that 301 is a keyboard related error, but
i am not sure what exactly the issue is.
Am i doing something stupid here or am i looking at the possibility of
something being wrong with the machine?
--Devin
10:02 p.m.
On Sat, 17 Dec 2016, Josh Dersch wrote:
Model M keyboards are AT-style keyboards, they
won't work with an XT
(different protocol). You will need to find a PC/XT compatible keyboard to
use.
exactly.
The original IBM PC/XT keyboard is a buckling spring.
So, if/when you find one, it will at least feel like a model M.
10:45 p.m.
On Sat, Dec 17, 2016 at 11:02 PM, Fred Cisin <cisin at xenosoft.com> wrote:
On Sat, 17 Dec 2016, Josh Dersch wrote:
IBM PC, PC/XT and original (84-key) PC/AT keyboards were Model F, which was
buckling spring with capacitive sensing.
IBM PC/AT enhanced (101 key) and many PS/2keyboards were Model M, which was
buckling spring with membrane (electrical contact).
Almost all non-IBM PC keyboards, even if they were expensive, were cheap
crap. Northgate was a notable exception, though they did offer some in the
"cheap crap" category also.
Model M keyboards are AT-style keyboards, they
won't work with an XT
(different protocol). You will need to find a PC/XT compatible keyboard to
use.
exactly.
The original IBM PC/XT keyboard is a buckling spring.
So, if/when you find one, it will at least feel like a model M.
10:53 p.m.
Alright, thanks for the info. I think I'll start off with something in
the "cheap crap" category and see if i can find something better down
the line. Now that i know what to look for it probably won't take long
to get one that is of good quality.
--Devin
On 12/18/2016 1:45 AM, Eric Smith wrote:
On Sat, Dec 17, 2016 at 11:02 PM, Fred Cisin <cisin
at xenosoft.com> wrote:
On Sat, 17 Dec 2016, Josh Dersch wrote:
IBM PC, PC/XT and original (84-key) PC/AT keyboards were Model F, which was
buckling spring with capacitive sensing.
IBM PC/AT enhanced (101 key) and many PS/2keyboards were Model M, which was
buckling spring with membrane (electrical contact).
Almost all non-IBM PC keyboards, even if they were expensive, were cheap
crap. Northgate was a notable exception, though they did offer some in the
"cheap crap" category also.
Model M keyboards are AT-style keyboards, they
won't work with an XT
(different protocol). You will need to find a PC/XT compatible keyboard to
use.
exactly.
The original IBM PC/XT keyboard is a buckling spring.
So, if/when you find one, it will at least feel like a model M.
11:51 p.m.
On Sat, Dec 17, 2016 at 11:53 PM, Devin <lyokoboy0 at gmail.com> wrote:
Alright, thanks for the info. I think I'll start
off with something in
the "cheap crap" category and see if i can find something better down the
line. Now that i know what to look for it probably won't take long to get
one that is of good quality.
After that AT (5170) hit the market, most of the clone keyboards that were
introduced either had a switch to select between XT and AT interface, or
did auto-switching. As XTs faded from common use, the clone keyboards
dropped that feature.
18 Dec
18 Dec
12:48 a.m.
> Alright, thanks for the info. I think I'll
start off with something in
> the "cheap crap" category and see if i can find something better down the
> line. Now that i know what to look for it probably won't take long to get
> one that is of good quality.
On Sun, 18 Dec 2016, Eric Smith wrote:
After that AT (5170) hit the market, most of the clone
keyboards that were
introduced either had a switch to select between XT and AT interface, or
did auto-switching. As XTs faded from common use, the clone keyboards
dropped that feature.
Which brings up:
How to tell whether a given keyboard is suitable for XT
It will have a 5 pin DIN (NOT mini-DIN) connector.
It will almost always be 83 key, but there were exceptions.
It will almost never have lights, but there were exceptions.
If it has an XT/AT switch, then it is OK!
If you find an 83 key keyboard, with 5 pin DIN and no lights nor switches,
then it could be XT, or it could be AT, with no external indication.
Which leaves part number, or opening it to check circuitry.
Should be possible to power it, and monitor the signals that it puts out?
You could try to make a microprocessor based adapter, . . .
30 years ago, people were trying to make adapters to use XT keyboards on
AT. Some of that information is still floating around.
Once "everybody" had upgraded to AT, most XT keyboards were dumpstered.
35 years ago, you could buy a keyboard to build a PC for $300.
So, maybe the eBay prices aren't so ridiculous?
7 a.m.
I have AT2XTKBD bare boards available for $5 each that were designed at
vintage-computer.com forums with the help of our very own Chuck Guzis.
https://retrobrewcomputers.org/doku.php?id=boards:other:at2xtkbd:start
Todd
* Fred Cisin <cisin at xenosoft.com> [161218 03:49]:
> Alright,
thanks for the info. I think I'll start off with something in
> the "cheap crap" category and see if i can find something better down the
> line. Now that i know what to look for it probably won't take long to get
> one that is of good quality.
On Sun, 18 Dec 2016, Eric Smith wrote:
After that AT (5170) hit the market, most of the
clone keyboards that were
introduced either had a switch to select between XT and AT interface, or
did auto-switching. As XTs faded from common use, the clone keyboards
dropped that feature.
Which brings up:
How to tell whether a given keyboard is suitable for XT
It will have a 5 pin DIN (NOT mini-DIN) connector.
It will almost always be 83 key, but there were exceptions.
It will almost never have lights, but there were exceptions.
If it has an XT/AT switch, then it is OK!
If you find an 83 key keyboard, with 5 pin DIN and no lights nor switches,
then it could be XT, or it could be AT, with no external indication.
Which leaves part number, or opening it to check circuitry.
Should be possible to power it, and monitor the signals that it puts out?
You could try to make a microprocessor based adapter, . . .
30 years ago, people were trying to make adapters to use XT keyboards on
AT. Some of that information is still floating around.
Once "everybody" had upgraded to AT, most XT keyboards were dumpstered.
35 years ago, you could buy a keyboard to build a PC for $300.
So, maybe the eBay prices aren't so ridiculous?
9:07 a.m.
On Sun, 18 Dec 2016, Todd Goodman wrote:
I have AT2XTKBD bare boards available for $5 each that
were designed at
vintage-computer.com forums with the help of our very own Chuck Guzis.
https://retrobrewcomputers.org/doku.php?id=boards:other:at2xtkbd:start
Wonderful!
THAT is the answer, if you don't already have an 83 key F.
17 Dec
17 Dec
9:59 p.m.
On Sun, 18 Dec 2016, Devin wrote:
I was happy to find a IBM XT for a good price at the
scrapyard today in very
nice condition. It is missing the hard drive, but i have plenty of those, the
controller was still inside.
If it is the real IBM (Xebec) hard disk controller, then it is strapped
for 10M.
Near the center are 8 solder pads. If you want, you can solder a 4
position DIPswitch to them, or just solder jumper wires as needed. It
supports two drives, two jumpers per drive. All open is 10M. (306
cylinders, 4 heads). IIRC, without modification other than those jumpers,
it supports 5M, 10M, 16M, and 26M?
Other configurations of drives can be accomplished by changing the ROM, or
in software.
I had a little issue getting video working at first, i
do not have a 9
pin cga monitor laying around, thankfully i found a 16 bit isa card that
also works in an 8 bit slot.
If it is a CGA card, then it also has an RCA jack and a 4 pin berg for
composite video, along with DE9 for CGA monitor.
If it is MDP, then it has DE9 for video and a DB25 for printer.
Pay close attention, they do NOT have the same frequency!
The machine starts up and runs its memory test,
however it gives a 301 error.
System halts and says press f1 to continue, but no luck, keyboard is
unresponsive. I have tried about 10 different keyboards on the machine,
including some model M keyboards with a ps2 adapter with no luck.
XT (5160, as well as 5150) keyboards are NOT interchangeable with AT
(5170) style keyboards. An AT keyboard will not work on an XT nor
vice-versa. For a brief time, there existed some keyboards with an XT/AT
switch on the under side.
Any keyboard with a PS2 adapter would be an AT keyboard. The XT keyboards
never had any connectors other than the 5 pin DIN.
Am i doing something stupid here or am i looking at
the possibility of
something being wrong with the machine?
You are right that a 301 error is keyboard.
You need to find an PC/XT keyboard; an AT keyboard will NOT work.
(Not even 10 of them :-( )
18 Dec
18 Dec
2:19 p.m.
On 12/17/2016 11:14 PM, Devin wrote:
The machine starts up and runs its memory test,
however it gives a 301
error.
Anything else alongside the 301? If it's a stuck key error then I think the
firmware spits out the scancode of the offending key (although maybe that
was only a 5170 and later thing?). Just a 301 on its own would indicate
something more fundamental.
Check the keyboard cable and connector carefully - I've seen plenty of
problems with DIN-type connectors on things, and I know that at least one
of my XT keyboards had damage where the cable goes into the back of the
keyboard. It may be worth (carefully) taking the keyboard apart to check
for obvious problems inside, and to check continuity on the keyboard cable
wires (I think it's a 4-wire setup - power, ground, clock and data -
although it uses a 5 pin connector with one pin unused)
Check for power at the keyboard socket on the motherboard (I don't have the
pinouts handy, but I'm sure that google does :-) and I believe there's a
PCB-mounted fuse on the system board near to the socket which is worth a look.
cheers
Jules
2710
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