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IBM Displaywriter 6580 Monitor Compatibility

I

Invisius

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May 18, 2016
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Hi folks, I recently picked up an IBM 6580 system in great shape, with the dual-disk drive (anvil) and 84-key keyboard. My only issue is that it's missing the monitor, and I can't seem to find one for sale anywhere (P/N 2683381).

I was able to find the display pinout for this system, and it looks like they use a only single cable for both power and signal transmission:

UBjCJ1y.png


From what I gather, none of the newer 5151-5154 displays could even be adapted for this since they use external power cables along with the MDA card. I did find some monitors from the 3101 terminals that look very similar, but can't find pinout info on them. If anyone knows whether these (or other displays) are compatible/adaptable, I'd really appreciate any help.

Here's a picture of my current setup.
 
Very clean looking Displaywriter, could you take a picture of the back of the unit please, be interested in seeing what options you have installed. Have you opened it up yet? there is a single screw (blade-type) at the bottom of the hole on the top (where the monitor sits), this secures the upper section of the case, once undone the top section lifts off easily. It would be good to see pix of the interior too.

It would be good to test the compatibility with other screens.
 
Hey there nigwil, I believe we spoke a few days back about the MDA pinouts. I've cleaned it quite a bit on the outside, but the inside is a very different story. Need to go all-out with some air duster before I even think about starting it up!

Here's the album I put together with the shots you asked for, some of the ICs are hard to read from all the dust. I at least tried to get the surface stuff out of the way. :p

Have no problem testing compatibility, as long as it won't go up in smoke when I do!
 
Invisius said:
From what I gather, none of the newer 5151-5154 displays could even be adapted for this since they use external power cables along with the MDA card. I did find some monitors from the 3101 terminals that look very similar, but can't find pinout info on them. If anyone knows whether these (or other displays) are compatible/adaptable, I'd really appreciate any help.
Click to expand...

OK so first things first. The manual says you can check the voltages on the back of the base unit with the display disconnected. This implies that you can just leave the power un-used if you don't need it. Second it says that the signals at the monitor are all inputs, so the display writer does not need any output from the monitor to inform it its connected.

So that implies we can use any monitor that will accept the scan rates the displaywriter outputs, albeit with perhaps some level shifting

I would guess that a normal IBM MDA monitor would be most likely to work, a with a cable that ignores the power issues. The signals look right, Video, Video Level, H-Sync and V-Sync so a two level display. It would be nice to pop a scope on the h-sync and v-sync pins to confirm the refresh rates, if I was having to spend real money on one I would get a scope out to check the voltage and frequency appearing on the sync pins....
 
g4ugm said:
OK so first things first. The manual says you can check the voltages on the back of the base unit with the display disconnected. This implies that you can just leave the power un-used if you don't need it. Second it says that the signals at the monitor are all inputs, so the display writer does not need any output from the monitor to inform it its connected.

So that implies we can use any monitor that will accept the scan rates the displaywriter outputs, albeit with perhaps some level shifting

I would guess that a normal IBM MDA monitor would be most likely to work, a with a cable that ignores the power issues. The signals look right, Video, Video Level, H-Sync and V-Sync so a two level display. It would be nice to pop a scope on the h-sync and v-sync pins to confirm the refresh rates, if I was having to spend real money on one I would get a scope out to check the voltage and frequency appearing on the sync pins....
Click to expand...

Very clever stuff, I've been looking into picking up a decent scope anyway, so this is just another excuse. :) Are you aware of any off-the-shelf adapters with this capability? Have no problem wiring something up, but figured I'd ask.

And since I can get the 3101 screen that already has a 15-pin connector for just a bit more than a 5151, do you think that'd be a better way to go? It draws power from the base unit just like the original, but I'm stumped whether the voltage matches.
 
Can you get a 3101 with base and screen, or just a screen. If you can get a base then you can check the power coming out of the socket and also scope the other signals to compare with the display writer. You could also ask the seller the part number, but I guess this is different. Both the 3101 (Nov 1979) and the display writer (June 1980) date from around the same time so they could be compatible, but you never know with IBM. They were so huge that any thing went.
 
Oh and you don't need an expensive scope for that. If , like me, you are short of space and cash consider a cheapo USB one from EBay, they are not what most folks would call a decent scope (not enough bandwidth, only 8-bit samples) but are fine for most Vintage work, where the max clock speed is 8 or 10Mhz. I have a Hantek 6022BE. Make sure you get a package with probes if you chose one. (Note I do have a 200Mhz bandwidth Hantek, a cheap TV scope with a real tube and a small Techtronic's but I generally use the 6022. Its cheap and I don't worry about blowing it up....
 
Further to this...

I have a complete (?) set of docs for the DW system, the full manuals and a substantial diagnostics supplement. Mostly I think technical, rather than for the operator.

The reason I got these - I was offered a complete system many years ago, but I was interested ONLY in the dual 8" floppy drive unit, which I have. Sat in the garage! Long been thinking of trying to do something with the drives (even just one of them ?) to attach to a CP/M system, or even an old DOS PC? The drives are pretty chunky things - I think they have a mains voltage AC motor? I do have some 8" floppies as well, but I'd need to create some sort of disk to use them, and I'd need some sort of format facility, but I'm sure I could work something via 22DISK which I'm pretty familiar with. My drives are BOTH the 2D type (higher capacity). I don't have any of the original DW system disks!

One day.....

Geoff
 
Regarding the two enquiries.

I have just two of the docs listed.

I have S241-6248-4 and S241-6250-7, both dated May 83.

These seem to be the ones containing the tech info that I'd be interested in.

Regarding the scanned images, my versions seem to be later versions than those in the scanned database. The scanned versions end -3 and -6 respectively. No idea what the changes might be, could be very minor??

Obviously, I have FAR FEWER of the manuals than I thought!! Sorry if I raised your hopes!!

Geoff
 
Sorry for the delay, the 3101 base and display finally came in today. I don't have the keyboard for the 3101, but managed to test what I do have:

D6P8RtY.jpg

For whatever reason, the Displaywriter keyboard doesn't work with the 3101 even though it has the same pin arrangement :(

I also measured the output on both sets of monitor pins. Both have single +12VDC and +5VDC outputs in the exact same position, but apparently something else is still off.

Displaywriter monitor pins:
gmppgoH.jpg


3101 monitor pins:
ZEQbUvy.jpg


I went ahead and plugged the 3101 screen into the Displaywriter, but completely blank. No damage at all, though. (knock on wood)
Really wish I could find the full manual for the 3101. Looks like I'm going to have to wait for my chinese-order scope comes in before going further.
To GeoffB17- my system didn't come with any blank disks or software at all, so I'm in a similar spot as you unfortunately.
 
Since this wasn't ever answered, the reason that the two keyboards aren't interchangeable is because they have different matrixes. The 3101 has a 24x4 matrix and the 6580 has a 12x8 matrix. The keyboard controllers are sending incompatible data over to the computer.
 
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