Challenger 3 OEM Restoration

CrawfordG
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Joined: Sat Jun 22, 2019 7:38 pm

Challenger 3 OEM Restoration

Post by CrawfordG » Mon Jul 08, 2019 11:10 am

Hello All,

My name is Crawford, I’m returning to OSI world having had a C2-4P back in the late ‘70’s.

I have. Challenger III bought off eBay, sat in my daughter’s basement for a while and now in my hands. I’ve been working on it for the last few months trying to get the disks to boot. Glitch and TangentDelta have helped me along, since I brought it with me to VCFEast in May.

Here’s where I am on this. I blew an electrolytic cap while runnng it for the first extended warmup. Fixed that, and have since been trying to get the 8 inch diskettes to work. At VCFE we found a blown driver on the disk board, glitch took it home, fixed and tested it. Still did not work in my system.

Next I discovered a dead small 5v power supply that powers the disk logic cards, and the last 2 motherboard slots (for some reason). I just replaced that supply.

So now the floppy steps to track 0 when I select D for disk at the H/D/M? Prompt. But I get no further than that. I guess I have to start troubleshooting the disk drives.

Any ideas where to start with the disk drive? It spins and steps. Power is good (now) for AC, 24v and 5v.

- Crawford

Mark
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Re: Challenger 3 OEM Restoration

Post by Mark » Mon Jul 08, 2019 4:55 pm

It might be informative to see what the C3 disk controller is reading.
After pressing D, if the data is being read, it should load at $2200 to $2EFF or so depending on OS.
You can view the data using the 65A ROM monitor. Try 'D', afterwards <RESET> press 'M', then 'P2200' (any keypress to exit).

I have a program on the tools section of my web page that can dump diskettes ( http://osi.marks-lab.com/software/files ... C3dump.zip ). You load it from the serial console on the C3, and control it from the serial port. It can provide the same information with a bit more friendly interface.

My 8" floppy drives have failed to read disks when the disk read head was not pressed close enough to the disk surface due to the foam rubber used to provide head-load pressure having decayed.

F.Y.I.
65A monitor commands as used by serial OSI systems
R - Reset
L - (load) <2 Byte Address in hex><data as hex> R to exit
P - (print) <2 Byte Address in hex> dump data at address, Any key to exit
G - (go) $0129=Y, $012A=X, $012B=A, $012C=P, $012D=K, ($012F,$012E) = RTI (GO) address

Good Luck!
-Mark

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glitch
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Re: Challenger 3 OEM Restoration

Post by glitch » Tue Jul 09, 2019 2:24 am

Good to see both of you here!

Crawford, make sure you've got good RAM throughout low memory. I chased bad SEMI4200s basically every time I set up my Challenger 3 until I got all of the bad ones weeded out.
Check out The Glitch Works
OSI Challenger 3, 510 CPU, 8" floppies, 74 MB hard disk system in need of restore
Parts bin Challenger 3 board set, never had a chassis in its time

CrawfordG
Posts: 11
Joined: Sat Jun 22, 2019 7:38 pm

Re: Challenger 3 OEM Restoration

Post by CrawfordG » Sun Jul 14, 2019 8:46 pm

Folks,

Mark, Jonathan - thanks for the info.

Well here is the status so far...

I filled in memory with values in a couple of places, then dumped it back out again. Granted this isn't a complete ram test, but seemed to be consistently giving back correct results. I filled in the area 2200 and above with zeros, then reset and tried disk boot. No change happened to the RAM at 2200-2eFF, so it looks like reading disks does not work. I will try Mark's disk dump routine next.

I took out the 2 disk drives and looked for differences. I was hoping to quickly swap the bottom disk to act as the top one for boot. No luck - there are a number of cuts and jumpers that need to soldered in, at the board edge connector area. I have tech manuals for the Siemens 100-8 drives, but the info doesn't seem to match my drives.

Other suggestions welcome.

-Crawford

Mark
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Joined: Tue Sep 16, 2008 6:04 am
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Re: Challenger 3 OEM Restoration

Post by Mark » Mon Jul 15, 2019 1:16 pm

I have two versions of Siemens FDD100-8 manuals at http://osi.marks-lab.com/reference/reference.html
I'll see what else I can come up with.
-Mark

CrawfordG
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Joined: Sat Jun 22, 2019 7:38 pm

Re: Challenger 3 OEM Restoration

Post by CrawfordG » Tue Jul 16, 2019 10:00 am

Folks,

So I did get Mark’s C3dump utility loaded, and found out the following:

Drive A erroerd out with the message that it could not detect index. So I guess there is something wrong with the photodiode, led, or related circuit.

Drive B seemed to start dumping out the disk. I’m not sure how far it got with that, as the disk is on the bottom, so I couldn’t see if it stepped all the way across the surface.

I tried to run it several times, but the system started freezing up. Maybe I should have heeded Jonathan’s advice about memory more closely! I’m only running one of the 16k boards. I built out one of the OSI-RAM boards, so will try that.

-Crawford

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glitch
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Re: Challenger 3 OEM Restoration

Post by glitch » Fri Jul 26, 2019 9:04 pm

Good progress! I put my C3 back on the bench and fired it up today for an interesting find, an unknown-to-me memory test program that seems to work. That doesn't do you a lot of good (at least for now) since it's on 8" disk and your drives aren't working.

Bad source/sensor pair for index is not a super uncommon failure. I've had two 8" drives in recent memory with that failure mode, one a Siemens and one a Tandon. You can check the source easy enough with a digital camera.
Check out The Glitch Works
OSI Challenger 3, 510 CPU, 8" floppies, 74 MB hard disk system in need of restore
Parts bin Challenger 3 board set, never had a chassis in its time

Mark
Posts: 55
Joined: Tue Sep 16, 2008 6:04 am
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Re: Challenger 3 OEM Restoration

Post by Mark » Sat Jul 27, 2019 1:18 am

So about the memory test....

I've updated the program published in the Small Systems Journal Vol.1 No.3 and made what I think is a universal program that should work on anything from an OSI400 ASCII system to C1E with Cegmon to C3OEM with terminal.

You can find it on the tools section of my website or here as an attachment.
There is no new functionality, it has just been patched & moved to work on video & serial systems, and to survive resets and CEGMON $200 page use.
Hopefully CEGMON won't touch $0236+ for simple <RESET> and monitor use. It survives resets on C3 systems too.

You can use it to test memory from $400 up. If the lower 1K is bad, the program won't run anyway.

I couldn't get the version available here on OSIWeb to work, but it has led me down a path which made me investigate undocumented opcodes, and caused me to update the A65 assembler to emit OSI 65V .lod files, as well as add a directive to specify execution address for MOS & 65V file formats. I'll be updating that on my web site too.

Let me know if this works as I haven't been able to test it on real hardware yet !
-Mark
Attachments
TestMem.zip
(58.91 KiB) Downloaded 49 times

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glitch
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Re: Challenger 3 OEM Restoration

Post by glitch » Sat Jul 27, 2019 2:05 am

Thanks for the memory test, Mark! I'll give it a try on the C3 either tonight or tomorrow!
Check out The Glitch Works
OSI Challenger 3, 510 CPU, 8" floppies, 74 MB hard disk system in need of restore
Parts bin Challenger 3 board set, never had a chassis in its time

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glitch
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Re: Challenger 3 OEM Restoration

Post by glitch » Sat Jul 27, 2019 3:06 pm

Well, it loads and runs, but I think this is probably the same program I've got on an OS-65D V3.3 disk on Track 75, the options are the same. The one I've got on disk had been modified to only print output after, if I remember correctly, 256 passes. It also had a BASIC program to print a help file with options and how to run it from disk. This new program also seems to exhibit the "random fail on a known good board" that I was getting with the copy I have on disk.

I pulled my GW-OSI-RAM1 and dug out a known-good vintage OSI 48K RAM board to do some testing on. It's 6116 based and very reliable. Perhaps I've got some marginal timing condition on the GW-OSI-RAM1. Seems unlikely with how many people have been using it, but we'll check!
Check out The Glitch Works
OSI Challenger 3, 510 CPU, 8" floppies, 74 MB hard disk system in need of restore
Parts bin Challenger 3 board set, never had a chassis in its time

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