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Northstar floating point card

Gary C

Gary C

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Does anyone have a FP card that I could have pictures of the topside without IC's inserted, or a picture of a bare board ?

I would like to recreate this board next but need to find an accurate picture of the top (and bottom, though they are not hard to find) to recreate the PCB

The IC's are available and the manual has the PROM contents but I just need to know where the tracks go under the chips !

Cheers.
 
If you mean the FPB-A then I believe that the IC sockets are the usual solid-bottom double-wipe sort, so removing the ICs isn't going to help in visualization. The sockets will have to be removed as well ...
 
X-Ray would solve it, but I found when I recreated the Votrax TNT that I could do it with a photo of both sides of the board, because I had the schematic, and it became obvious where the tracks that went under the IC's connected from the positions that they passed under the IC or socket helped too as they don't cross over, unless there are vias under the socket, but you can see those from the photo of the board's bottom. So it won't be required to remove the sockets from any original board to do it, that is if you have the schematic.
 
Hugo, Yes, your right of course and I do have the schematic.

It just would be easier with a clean view of the top :) Your Dazzler pcb traces made that fairly easy and I was hoping to do the same
 
But it doesn't have enough contrast to be able to see enough detail (especially along the bottom)

Still need a really good picture of a board, even with IC's.

Anyone got one ?
 
Gary C said:
But it doesn't have enough contrast to be able to see enough detail (especially along the bottom)

Still need a really good picture of a board, even with IC's.

Anyone got one ?
Click to expand...
Interesting board. I saw some more images on the Deramp site that might help.

It seems that Northstar BASIC had the appropriate "driver" software embedded to make it work seamlessly with their own BASIC.

I wonder if Northstar BASIC would run in a SOL-20 with an 8080, oe whether it needs a Z80 to run ?
 
I have a northstar floating point card, and would be willing to help when I get a chance (although I'm super busy, so I'm flakier than ideal). I also have the northstar basic which supports the board. It's on paper tape, and unfortunately I don't have a paper tape reader (another acquisition on my to do list).
 
Problem with recreating a PCB is getting an accurate, undistorted view in high enough resolution to trace out the tracks (yes the schematic can help but they do often have missing bits).

I have FPBASIC on disk which I assume is the version for this card.
 
monahan_z said:
Might want to take a look at this newer Math board.
S100 Computers Math Board
Click to expand...
That is a very impressive project.

I have never found the TIL311 difficult to get or too expensive. After a while, for a different reason, I moved to the low current cmos plug in replacement version, these are much more efficient and run cool compared to the TIL311. A large array of TIL311's is quite a power hungry and heat generating affair. I bought a number of tubes of the cmos parts from the manufacturer, Innocor in Canada. the INL-0397-1.

Sadly, the Innocor parts did become near impossible to get when they stopped making them.

After that I moved to the Avago / Broadcom HDSP -0962 bright green, or red hexadecimal displays with 4 bit inputs, latches etc. These displays are super high quality ceramic & glass mil spec style construction. The package/pinout is different though to the TIL-311. The thing with these ones, they are not cheap, they are mil spec quality parts. These ones can be seen on the second to last page of this article:

 
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https://forum.vcfed.org/index.php?threads/amd-am9512.22220/ from 14 years ago is worth a read.

Correct me please, but doesn't N* BASIC have specific provisions for the FPB? Note also, that the FPB uses N* own decimal floating point format.

I find the Northstar FPB board fascinating. With nothing more complex than a 74181, they managed to fit a floating-point processor on an S100 board, using only SSI TTL.

I wonder if the Northstar FPB could be simplified using more modern parts.
 
Yes, N* FPBASIC works with the FPB

The board is almost as fascinating as the Dazzler in what it gets out of 74 logic.

It looks though as if I am going to have to create a proper Kicad schematic before I can route the tracks and that's assuming it has no errors which would not be unexpected
 
Schematic completed, just needs fully reviewing (just found some errors on page 1 this morning)

Page 1.pngpage 2.png

Just need to finish checking page 2 and correcting the errors I have and will find, then I should be able to complete the PCB layout.
 
This is fantastic. I can say as someone who's done it you can uncover many issues by copying the layout of the board and suddenly you find 'why is kicad encouraging me to short d0 to d1?' and then realize you messed up a bit on the schematic. Also, use github. Upload everything as you go and commit and push each night. It's easy to get sidetracked with work or other stuff and forget what was going on and maybe misplace the laptop or lose a boot drive. Ask me how I know.
 
almost done. The schematic is essential, its allowed me to work out some of the layouts for which the images are too fuzzy, and conversely the PCB has helped debug the schematic

Just got the decoupling capacitors to finish

1739349360321.png
 
Its a lot harder than doing the Dazzler layout as Hugo's foils were very accurate. The images I have been using are fuzzy and distorted.
 
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