• Please review our updated Terms and Rules here

Osborne 1 keyboard interface?

Yeehaa - found it! Champollion would have been proud of you for the deciphering!

There are letters, but no numbers, on the board edges. So I eyeballed the E row, and found DM81LS95N.

There are ten pins on each side of that IC. I don't know which ones to test, so I'll report on all 20.

Stay tuned ....

TM
 
Well done.

Further education...

If there is a round indentation on the IC this is pin 1 - the pins are then numbered anticlockwise around the IC.

If there is a cut-out on the narrows edge of one side of the IC - the left-hand pin (with the cut-out facing uppermost) is pin 1.

Dave
 
daver2 said:
Well done.

Further education...

If there is a round indentation on the IC this is pin 1 - the pins are then numbered anticlockwise around the IC.

If there is a cut-out on the narrows edge of one side of the IC - the left-hand pin (with the cut-out facing uppermost) is pin 1.

Dave
Click to expand...

Thanks. There is a raised bump at one corner, so I presume that marks pin 1. So the eight pins I should test are the sequential pins 1 through 8 all on that side - in other words, the first eight pins on the side beginning with the pin marked with the raised bump.
 
Here we go - voltages on the first eight pins down the side of the IC starting with pin 1 marked with the dimple:

Empty keyboard terminal:

Pin 1 - 3v
Pin 2 - 5v
Pin 3 - 2v
Pin 4 - 5v
Pin 5 - 2v
Pin 6 - 5v
Pin 7 - 3v
Pin 8 - 5v

Cable inserted, but no keyboard attached:

Pin 1 - 3v
Pin 2 - 5v
Pin 3 - 2v
Pin 4 - 5v
Pin 5 - 2v
Pin 6 - 5v
Pin 7 - 3v
Pin 8 - 5v


Cable and keyboard attached:

Pin 1 - 3v
Pin 2 - 5v
Pin 3 - 2v
Pin 4 - 5v
Pin 5 - 2v
Pin 6 - 5v
Pin 7 - 3v *but screen goes to garbage and A drive spins*
Pin 8 - 5v *result same as pin 7*

Edit: as earlier, when both the cable and keyboard are connected, the screen begins to flicker. When I checked all the pin voltages and got to pins 7 and 8, that's when the "nervous breakdown" began.
 
Last edited:
It's interesting about pin 8 - it shouldn't do that!

Can you re-read my last post please, you have only done half the work!

Can I suggest repeating the same 3 tests, but with the pins on the other side of the IC. In fact, can you measure the voltages on all 10 pins of the other side for completeness please?

I will checkout the schematics when I have recovered from my afternoon walk!

I have just checked the schematics. Pin 9 could be significant as well. Can you measure that as well?

Cheers,

Dave
 
Last edited:
So, I am trying to definitively understand which way round this cable is supposed to be fitted between the Osborne 1 computer and the keyboard itself.

I have found a website with a description http://old.pinouts.ru/Inputs/osborne_keyboard_pinout.shtml.

This quite clearly shows the connector pinout in the upper-left of the webpage and a description of each pin in the body of the webpage. Notice the little cut-out in the connector shroud in the upper-left image.

Looking at the picture here https://www.techrepublic.com/pictures/cracking-open-the-osborne-1-the-original-portable-computer/27/ you can quite clearly see the cut-out on the image - leading me to the conclusion that on your machine (if you look into it from the front) the cut-out is uppermost leading me to suspect that pin 1 is on the upper-right of the connector. This agrees with the text on http://old.pinouts.ru/Inputs/osborne_keyboard_pinout.shtml.

I have checked the schematic and it agrees with these pages (as far as I can tell).

There are some further photographs (especially https://www.techrepublic.com/pictures/cracking-open-the-osborne-1-the-original-portable-computer/4/ and https://www.techrepublic.com/pictures/cracking-open-the-osborne-1-the-original-portable-computer/12/) showing how the ribbon cable is attached to the keyboard and computer respectively. Notice the stripe on the ribbon cable on the connection to the keyboard.

Do these photographs agree with how your keyboard is connected to your computer?

It looks from the photographs that the keyboard is a 'naked' male connector (and therefore the ribbon cable can be put on upside down) and (even though the computer IDC connector has a polarising cut-out) the corresponding connector on the ribbon cable may not have a corresponding polarising 'bump' (i.e. it can also be connected the wrong way round).

Dave
 
I am suspecting a fault within UE12 (81LS95) - but before we jump to that conclusion I want to rule out a few things. I want to first checkout that a resistor pack (RN10 - 1k) is OK. Then I want to checkout that the keyboard and cable is OK. Then I want to test out UE12 to confirm my suspicions.

Firstly. Switch off your Osborne and disconnect it from the mains. Secondly, disconnect the keyboard and ribbon cable.

Set your multimeter to read resistance. We want to measure approximately 1 kOhm. Don't forget to 'zero' your multimeter by shorting the two probes together and adjusting the meter reading to read 0 Ohms.

With the keyboard and ribbon cable disconnected - and the Osborne switched off and disconnected from the mains; use your multimeter to measure the resistance of UE12 pins 2, 4, 6, 8, 12, 14, 16 and 18 to +5V (UE12 pin 20). Connect your multimeter probe to UE12 pin 20 and UE12 pin 2 and measure the resistance. It should be round about 1 kOhm. Move your multimeter probe to read between pins 20 and 4 and take another reading. repeat for all identified pins to UE12 pin 20. All of the resistance readings should be similar and round about 1 kOhm.

If you want the pinout of UE12 (81LS95) checkout http://www.elektropage.com/default.asp?tid=637.

Next, connect up the keyboard and ribbon cable to the Osborne 1 - but leave it switched off and disconnected from the mains. All of the following readings are UNPOWERED.

Look up the key matrix again in your technical manual. I will use the one I found at http://old.pinouts.ru/Inputs/osborne_keyboard_pinout.shtml.

You will notice the key matrix has A0 to A7 down the side and D0 to D7 across the page. Each key sits at the intersection between an 'A' and a 'D' line.

A0 is connected to UE14 pin 10.
A1 is connected to UE13 pin 10.
A2 is connected to UE13 pin 12.
A3 is connected to UE14 pin 6.
A4 is connected to UE14 pin 8.
A5 is connected to UE13 pin 8.
A6 is connected to UE14 pin 4.
A7 is connected to UE13 pin 6.

D0 is connected to UE12 pin 4.
D1 is connected to UE12 pin 8.
D2 is connected to UE12 pin 14.
D3 is connected to UE12 pin 18.
D4 is connected to UE12 pin 16.
D5 is connected to UE12 pin 12.
D6 is connected to UE12 pin 6.
D7 is connected to UE12 pin 2.

UE12 is an 81LS95 (see http://www.elektropage.com/default.asp?tid=637 for the pinout).
UE13 and UE14 are 74LS05 (see http://www.datasheetdir.com/SN74LS05N+Inverters-Gates for the pinout).

Obviously, from your new-found training, you know that UE13 and UE14 are on the same row (E) and are next to our (now familiar) UE12!

So, if you look at the key matrix, the 'RETURN' key is connected between A0 and D5. From my table above you should be able to read the resistance from A0 (UE14 pin 10) to D5 (UE12 pin 12). With the key not pressed - this should be a fairly high resistance. With the key pressed - this resistance should drop to a virtual short circuit.

Let's do one more for you - try the 'A' key. This lies at the intersection of A3 and D0. A3 is UE14 pin 6 and D0 is UE12 pin 4.

Print out the key matrix page from the Osborne technical manual and test ALL of the keys as above. Tick them off as you go.

We are only performing positive tests here (making sure that the keys are connected to where they should be). Once you get into a rhythm it shouldn't take you that long. Going across the rows or down the columns should be the easiest. Obviously, if there is no key there (e.g. A0 - D3) there is nothing you can do about this.

Before I come up with the next test - can you clarify one thing? You say that the new keyboard you bought does the same thing. Are you using a new ribbon cable or not?

See what results you get from this test. If everything checks out OK - there must be a problem with UE12 (but my next test should confirm this).

Dave
 
If you look at the image here https://www.techrepublic.com/pictures/cracking-open-the-osborne-1-the-original-portable-computer/34/, UE12 is just to the right of the blue resistor pack marked RN10. You can just see the device identification on the IC as "DM81LS95" with the 'N' just disappearing off the edge of the photograph.

It is also just to the left of the text "C78".

For interest (!) the IC UE12 was made in week 28 of 1982... And the marking DMP is most likely the manufacturing facility that made the device.

Dave
 
"Before I come up with the next test - can you clarify one thing? You say that the new keyboard you bought does the same thing. Are you using a new ribbon cable or not?"

I tried both the original and the replacement keyboard, and three cables. The replacement keyboard worked correctly on the O1 it came from. I've also tried each of the cables with the ends turned "upside down" one at a time. None of the orientations change the problem: the CRT flickers and the keys don't do what they're supposed to.

As I said earlier, the keyboard (either one) will do its job - each key works correctly - and the three cables appear to work correctly, if I hold down a key and lightly touch the female connector to the pins, then left it back up. But if I push the connector solidly down onto the pins, the CRT flickers and the keys cease working properly.
 
daver2 said:
If you look at the image here https://www.techrepublic.com/pictures/cracking-open-the-osborne-1-the-original-portable-computer/34/, UE12 is just to the right of the blue resistor pack marked RN10. You can just see the device identification on the IC as "DM81LS95" with the 'N' just disappearing off the edge of the photograph.

It is also just to the left of the text "C78".

For interest (!) the IC UE12 was made in week 28 of 1982... And the marking DMP is most likely the manufacturing facility that made the device.

Dave
Click to expand...

As I said in post #21, I already found that IC and did the pin voltage checks. Not sure why you're just now pointing out where the IC is.
 
Thanks - so you have tried multiple cables (3 off) and 2 keyboards - so we should be able to rule out a cable fault.

What I am trying to do here is to rule out that one of the resistors within the RN10 resistor pack has gone faulty. This is (however) quite unlikely based on my knowledge of failure rates for a component of this type. If one was to go faulty, then connecting a long pies of wire (the keyboard cable) to the input of an IC (UE12) with the input floating (faulty resistor) - and then to place that piece of wire in close proximity to other signals that are varying (the keyboard) would mean that stray electrical noise would be picked up by the lead and will confuse the firmware (i.e. the wire will act like a radio antenna).

This would fit your symptoms... However, as I have explained, it is an unlikely (but not 0) probability.

Dave
 
>>> As I said in post #21, I already found that IC and did the pin voltage checks. Not sure why you're just now pointing out where the IC is.

VERAULT was asking - so I pointed them to a photograph of the IC in question on the internet and was pointing out to them where it was within the photograph. That's all.

Dave
 
Gentlemen - I'm getting really overwhelmed with the details and sometimes unclear to me instructions. Sometimes I can't even keep following the posts, as the system sends email updates about ten minutes after the posts are made, and I've already read a post and/or replied. Verault asked me to post the IC photo; I was looking for a photo for him, not expecting you to answer him.

Two questions not answered so far: 1. to boot with system disk in the B (right) drive, what key combination is used?

2. as there's no indication on the cable terminals of "faces up" or "faces down", there's certainly the possibility that at one time I attached the cable upside down to the m/board terminal. Would that cause permanent damage when the system powered up?
 
OK, so let's take things a bit more slowly...

The answer to your booting from Drive 'B' can be found with google over at http://www.vintagecomputer.net/browse_thread.cfm?id=172 or http://www.vcfed.org/forum/showthread.php?41497-osborne-1-boot-error as the key combination:

SHIFT "

I am led to believe.

EDIT: The technical manual http://www.bitsavers.org/pdf/osborne/osborne1/2F00153-01_Osborne1TechnicalManual_1982.pdf page 64 section 10.2 states RETURN to boot from drive A and " to boot from drive B. To get a " you have to use the SHIFT key simultaneously.

The answer to your second question is it depends upon which revision of the Osborne 1 printed circuit board you have. Depending upon your revision (and this can be found on the main board PCB as follows https://www.techrepublic.com/pictures/cracking-open-the-osborne-1-the-original-portable-computer/36/) there may be +12V on pin 19 of the keyboard connector (depending upon whether a link is inserted by default or not). You have one pin missing on your keyboard connector that I believe is pin 1 (0V) which may mean that +12V is present on pin 19. If this is the case - and you have inserted the keyboard connector incorrectly - then you may have inadvertently caused some damage to either UE12, UE13 or UE14 if you press some keys on the keyboard (you will have connected +12V to some logic ICs that will only tolerate +7V at most).

I propose we proceed by you asking a question and me answering it. How does that sound?

Dave
 
Last edited:
OK - my m/board does indeed show Rev. F.

As you remember from my previous photo, the upper right pin is missing on that m/board keyboard (male) terminal.

So - as two UE12 pins are causing CRT/display and drive problems when tested with the volt meter, wouldn't that indicate the problem is the IC (or other m/board parts)?

In other words, if the problem is on the m/board, I'd be better off replacing the m/board I'd think.
 
That's one way of looking at it.

However, touching your voltmeter on pins 7 and 8 of UE12 - and the machine going 'screwy' in both cases is not registering as a valid condition in my mind. Pin 7 is an output of one internal gate within UE12 and pin 8 is an input of a separate gate within UE12. To get a similar behaviour from the output of one gate and the input of another is an unlikely scenario (but not impossible).

One possibility (when you have taken the readings with your voltmeter) is that you have inadvertently made connection with the probe (in both cases) to something else. This would produce the symptoms you state - but this is not a fault of the board...

If you have done some damage by accidentally reversing one end or the other of the keyboard cable - then it would be better to know this for sure. If this was the root cause of the main board failure - and you purchase a new main board and incorrectly fitted the keyboard cable again - you may damage that.

Thoughts?

Dave
 
That's one way of looking at it.

However, touching your voltmeter on pins 7 and 8 of UE12 - and the machine going 'screwy' in both cases is not registering as a valid condition in my mind. Pin 7 is an output of one internal gate within UE12 and pin 8 is an input of a separate gate within UE12. To get a similar behaviour from the output of one gate and the input of another is an unlikely scenario (but not impossible).

One possibility (when you have taken the readings with your voltmeter) is that you have inadvertently made connection with the probe (in both cases) to something else. This would produce the symptoms you state - but this is not a fault of the board...

* * * I did get the CRT/drives misbehavior on pins 7 and 8 with three separate tests with the cable and keyboard attached. Didn't get the misbehavior with just cable or no cable/no keyboard. That would seem to indicate I was doing the test properly.

If you have done some damage by accidentally reversing one end or the other of the keyboard cable - then it would be better to know this for sure. If this was the root cause of the main board failure - and you purchase a new main board and incorrectly fitted the keyboard cable again - you may damage that.

* * * Good point. But on one cable, there's only one way the m/board female can fit, and one way the keyboard female can fit. Problem is the same with that cable, as well as the two "unpolarized" cables. It's the coiled cable, similar to: https://www.richardloxley.com/wp-content/uploads/2018/04/IMG_9500-600x450.jpeg
That's probably another reason to think the m/board is the culprit, not the cables or keyboards.

Thoughts?

Dave
 
You must log in or register to reply here.
Back
Top