Sol 20 up and running (I hope)

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Terry Fox

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Feb 22, 2026, 10:53:03 PM (11 days ago) Feb 22
to Altair 8800
I just tested the 21L02 buffer RAM (not video) using my handy-dandy Retro Chip Tester, and sure enough one chip was bad.  Now things seem to be running better, I can do a dump, etc.

More testing before declaring complete success.  Now, off to figure out what's wrong with my Synology NAS (other than just being Synology).

Thanks Mike and others for the help@
Terry

Walt Perko

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Feb 22, 2026, 10:56:32 PM (11 days ago) Feb 22
to Altair 8800
Hi, 

Cool!  Maybe when you're ready you can do a demo of the Multi-BOOT Personality Module ... because my Sol-20 is down, I haven't been able to figure it out to make a setup and run page on my website ... or video.  


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Joseph Corda

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Feb 22, 2026, 11:01:40 PM (11 days ago) Feb 22
to Terry Fox, Altair 8800
Great news Terry..   Hmm I need to get one of those Retro chip testers
Joe

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Terry Fox

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Feb 23, 2026, 12:09:48 AM (11 days ago) Feb 23
to Altair 8800
Well, as usual anymore, I spoke too soon.  I put it back together, and all I see is a screenful of 9090909090.
I found that if I remove the S100 riser, the SOLOS prompt shows back up.  As soon as I install the riser it does the 90909090 again.  I've visually checked the connectors and can't see anything wrong. More testing tomorrow.
Terry

Walt Perko

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Feb 23, 2026, 12:14:24 AM (11 days ago) Feb 23
to Altair 8800
Hi, 

Ya gotta love the Vintage Computer Hobby.  At least you have a huge head start in repairing boards and getting things up 'n running.  

I'm still amazed how Mike recognized the problem on my Altair 8800c Front Panel as a few wires from the CPU board to the Interface board being in the wrong places.  But now I know how the clue was realized.  


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Terry Fox

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Feb 24, 2026, 3:20:36 PM (9 days ago) Feb 24
to Altair 8800
Another update:
I found the S100 riser pin 58 was shorted to ground under a connector.  After resoldering pin 58 on all riser S100 connectors, it went away, and the Sol is now working better, with a 16K econoRAM and 32K RAM20 board in the riser section.  Now I need to find something (monitor?) to test RAM, and bring up some kind of floppy disk controller.
Terry

Walt Perko

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Feb 24, 2026, 5:43:46 PM (9 days ago) Feb 24
to Altair 8800
Hi, 

I think the best place to start is:  https://www.sol20.org/programs.html

Maybe contact Francis Bauer ... or ... Jonathan Chapman ... 


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Mike Douglas

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Feb 24, 2026, 6:33:10 PM (9 days ago) Feb 24
to Altair 8800

Here’s a memory test that fits in the hole in SOLOS RAM so you can test RAM boards on the S-100 bus.


Mike D

Terry Fox

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Feb 24, 2026, 11:38:30 PM (9 days ago) Feb 24
to Altair 8800
Thanks Mike and Walt. I will try the test that Mike sent in a day or two.  I just tested out a N* DD controller and a couple of Tandon drives.  Now I need to make a 34-pin cable.
Terry

Terry Fox

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Mar 2, 2026, 4:29:01 PM (3 days ago) Mar 2
to Altair 8800
 Here we go, an update on my Sol 20 from last night's testing.

After the Zoom call, I found my SSM 8k RAM boards.  I put first one board in at 8000, it passed RAM tests.  Then I added a second board at A000, it also passed RAM tests.

I then found a Proc Tech 16K RAM Plus board, and replaced the two SSM 8K boards with it.  That also passed, so I plugged back in the 32K RAM board @0000, and all the RAM passed.  Today, it is still passing RAM from 0000 to BFFF.

So the 16K EconoRAM IV board is definately bad.  I think there is a bad RAM chip somewhere.  Time later to work on that, for now, I will start adding the N* floppy system.

Thanks everyone for all your help!
Terry

Terry Fox

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Mar 2, 2026, 4:55:03 PM (3 days ago) Mar 2
to Altair 8800
Duh,
Seattle computer 16K Plus board, NOT Proc Tech
Terry

Joseph Corda

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Mar 2, 2026, 10:08:55 PM (3 days ago) Mar 2
to Terry Fox, Altair 8800
Terry 
Glad to hear of the progress .. crossing fingers that memory continues to pass the tests and it stays stable for you!
Joe

Terry Fox

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Mar 3, 2026, 12:45:25 AM (3 days ago) Mar 3
to Altair 8800
YAY!!!
A HUGE WIN!!!!!!!
Thanks to Mike and his Sol software site, I was able to write a N* CPM disk, and then boot it!  It took several floppy disks to get it to work (mostly dirty floppies), but it did.

So now I need a few clean/good floppies.  Anybody have a box of Northstar DS/DD or QD 10 sector floppy disks they wouldn't mind selling me?  Most of my 40+ year-old ones look to have some mildew on them.

Again, YAY!
Terry

Walt Perko

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Mar 3, 2026, 2:36:44 AM (3 days ago) Mar 3
to Altair 8800
Hi, 

Do any of the disks for sale here fit the bill?  



Tomorrow I can look into my stash of floppies to see if any have 10-sector holes.  Mold doesn't grow in Southern Nevada.  


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Joseph Corda

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Mar 3, 2026, 7:33:53 AM (3 days ago) Mar 3
to Walt Perko, Altair 8800
Not to steal Terry's request ..  but I would like to get on the list after Terry so if there are any still available please let me know as well.  
I have a Horizon North Star (still to be restored) that I would like to get some real hard sector media (10 sector).

As my past searches have not yet located any compatible hard sector disks,  I did purchase Mike's Virtual Sector Generator https://deramp.com/vsg.html so if my drives are in decent shape and
have acceptable ISV (Instantaneous Speed Variation) I'm hoping to use soft sector media.
Joe 

Walt Perko

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Mar 3, 2026, 5:54:47 PM (2 days ago) Mar 3
to Altair 8800
Hi,  

Once I could find the 10 Sector dimensions online, it only took about 2-minutes to make a sketch in SolidWorks and a .DXF vector file (attached) so people can make themselves a punching template:  

5.25in Floppy Disk -00.jpg




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5.25in Floppy Disk -00.DXF

Walt Perko

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Mar 3, 2026, 6:12:29 PM (2 days ago) Mar 3
to Altair 8800
Hi, 

I forgot to add a 3D Printable file ... 5mm thick to increase vertical punching ... print two of these, line up the holes with the two side notches and start punching.  


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Bottom Template 5.25in Floppy Disk -00.STL
Top Template 5.25in Floppy Disk -00.STL
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