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GRiDCASE Tempest 1307

M

M41A

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Mar 22, 2025
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My Uncle gave me this GRiDCASE Tempest today while visiting him. I’ve done a decent amount of research online but haven’t found much info about the 1307 Tempest other than it was generally used by the military. He said it doesn’t boot and he couldn’t find the power cord for it.

I love vintage computers but find myself admiring the thought of them and how they look rather than getting into electronics repair or programming. Is there a go-to source for information or possibly repair on these or is it better to just clean it up and tell a good story about what it might have been used for?

He had the box with it and I’m wondering if GRiD would divulge who the original customer was who ordered it. Doubtful but would be cool.
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ajacocks said:
Wow, that's cool that you not only have the machine, but some of the story behind it.

Welcome to the forum!
- Alex
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My Uncle worked for a bunch of defense contractors from the 60s-90s and was involved in a lot of projects he still can’t talk about, but he said he acquired this computer on his own because he needed a way to communicate with some HP hardware he had in his workshop at home (IEEE 754 I think?). He’s almost 80 years old and has a workshop full of radios and vintage electronics from back in the day. His career was largely based on air to ground missile guidance.
 
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Definitely, start with cleaning and storytelling!
Forum will help you repair GRiDcase 1307.
 
So the one thing that strikes me as odd is that the power supply is removable and the floppy drive is present. I'm fairly certain (but I've only seen one example) that is not actually a TEMPEST model in favor of a regular spec GRiD. You'll know for certain when you open it and you'll find a doubling-up of the EMI shielding.
 
NeXT said:
So the one thing that strikes me as odd is that the power supply is removable and the floppy drive is present. I'm fairly certain (but I've only seen one example) that is not actually a TEMPEST model in favor of a regular spec GRiD. You'll know for certain when you open it and you'll find a doubling-up of the EMI shielding.
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I will take some pictures when I get back from work but when I took the plastic piece off above the keyboard there was a metal enclosure with two screws that’d completely encapsulated a PCB with rom chips on it. It did not look like others I’ve seen that had empty rom chip sockets.
 
That is still one of my favorite systems to use as a terminal. If it has the Grid ROM will boot directly or just build a DOS 720K floppy and will run from that. I use a old terminal program called TERM that works great with that old hardware. used it a lot with a Rolm 1602 computer and all my videos with the 1602 work with that terminal. Old video of one at work.


Still have a ton of grid laptops that i got to do something with some day along with some of the tablet systems. Sold off all my DEC stuff a while back and then a truck load of Rolm military stuff. don't know if i would ever sell the Tempested system.
 
Qbus said:
That is still one of my favorite systems to use as a terminal. If it has the Grid ROM will boot directly or just build a DOS 720K floppy and will run from that. I use a old terminal program called TERM that works great with that old hardware. used it a lot with a Rolm 1602 computer and all my videos with the 1602 work with that terminal. Old video of one at work.


Still have a ton of grid laptops that i got to do something with some day along with some of the tablet systems. Sold off all my DEC stuff a while back and then a truck load of Rolm military stuff. don't know if i would ever sell the Tempested system.
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You're lucky, yours has the rare EL screen. I've always wanted to see one of those in person.
 
Question for you.
When you open yours up, are the contact surfaces between the unpainted magnesium and copper corroding? Others have noted that the two metals don't seem to like eachother.
 
What’s the preferred method for disassembly? Pretty straight forward and just remove screws from the bottom?
 
This is really cool. And cool uncle too. Very unique computer. And EL screen too!
Ideally you should use 16V power supply but GRiDs are fine with anything betwen 12 and 18V.
 
NeXT said:
Question for you.
When you open yours up, are the contact surfaces between the unpainted magnesium and copper corroding? Others have noted that the two metals don't seem to like eachother.
Click to expand...

I can answer your query purely as a question of chemistry, metallic copper and magnesium in contact with one another is an excellent example of galvanic corrosion.
 
Sorry I haven’t taken it apart yet but wanted to post this picture as well. I noticed it had different info on the back compared to non-TEMPEST GRiDcase models I’ve seen. The sticker on the left references a NACSIM 5100A spec for cables, and the pull down support is devoid of some information I’ve seen on others.

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I took the top of the back part of the case off this afternoon. I still need a power supply or power adapter for it to see if it works. I think it needs a 6.5mm x 2.0mm plug but can't find one.

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I found this "label" at the back of the power supply that came with my GRIDCASE 4 (I'm not sure what series-number it corresponds to, but our two systems look very similar).

16.25V 3.7A

I don't think the 3-pin circular connector actually connects to anything (at least when used for this system). Then it's not apparent which of the large metal pads is + vs - . I guess that's easy to determine, just check continuity between one pad and any metal chassis piece?

Get a variable power supply, use some playdoh to temporary hold power to these leads, and flip that power switch :) Good luck.



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The 3 pin connector is for using it as external power supply on newer gridcases.
I have some cartridge PSUs like that, and some with barrel jack connector. They are to be used as external PSU when the battery is installed.
BTW, I also noticed yesterday that cartridge opening on the backplane is slightly larger on 1550sx vs 1520/30.
 
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