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jharre
September 16th, 2013, 02:31 PM
Found a TeleVideo TS-802 and keyboard on eBay recently that looked like a reasonable deal for less than $100 delivered. {Of course, I didn't know that the seller was going to wrap the computer in brown kraft paper, tape it up, slide it into a box with 4" of space all around, then mail it Postal Select - it survived! They certainly don't make 'em like they used to.}

But, I digress. While waiting for it to arrive, I found that some kind soul published a ton of TeleVideo stuff on bit-savers and was able to use ImageDisk to create a couple new CP/M 2.2 diskettes. When unwrapped and powered on, it did attempt to boot, but both of the floppies had physical problems. I plugged in a good half-height floppy and, as you can see on the screen, it says it is booting then starts putting dots on the screen. It'll do this for hours.

I don't know if the dots mean it has read a sector or maybe it means it couldn't read a sector. The head never seems to move other than initially when the system is powered on or reset and it seeks to track zero.

The chips in sockets have all been reseated on the board. The cable from the mainboard to the floppy daughter and the cable to the drives have been removed and reseated. Voltages look pretty close. The display looks rock solid and the indicator leds on the mainboard do their dance at reset and stay off. I've made a few different boot disks in case one was marginal.

It just won't boot.

Some machines of this era had a monitor you use to see what's going on (like error codes from the WD1793 FDC), but the 802 doesn't seem to have this feature.

Anybody have ideas what to try next?

1524115242152431524415245

Chuckster_in_Jax
September 16th, 2013, 06:23 PM
I have a Televideo TS-802 with EXACTLY the same problem. It got put on the "list" to be repaired and I haven't got back around to looking at. I have thought that maybe the disks I was using were for a TS-802H with a hard drive and the OS was looking for a hard drive and couldn't find it.

billdeg
September 16th, 2013, 07:20 PM
Hmmm..may be looking for a hard drive. Did you try ctrl+c to break out (no idea if that would work) or something along those lines? Are you sure the disks work .. Do they work in a known working system? May not be possible to determine this, I realize. I would suspect the disks are the culprit not the system. Just a hunch.

Chuckster_in_Jax
September 17th, 2013, 01:32 AM
I posted 4 years ago about this problem here:

http://www.vintage-computer.com/vcforum/showthread.php?14521-Televideo-TS802-Boot-Disk-Looking-for&highlight=TS802

I finally found an image of the boot disk for a TS802H. I wonder if the disk image floating around out there is bad.

jharre
September 17th, 2013, 06:06 AM
billdeg: hadn't thought of trying that - it accepts ctrl+c a few times until the keyboard buffer fills up and then just beeps. No, I'm not sure the disk images are good. Wish I had a working system to test them in! :)

I picked them up from the TS-802 folder at http://bitsavers.trailing-edge.com/bits/Televideo/ (http://bitsavers.trailing-edge.com/bits/Televideo/http://) . My testing was done with the TS802_CPM2.2_VER_2.1.IMG and 802_Turbodos.IMD images. After creating a disk using ImageDisk v1.17 (the latest I could find on Dunfield's site), I used Uniform to set the PC floppy to read TeleVideo format and verified that there was at least a directory with reasonable looking contents. Of course, that doesn't guarantee there is a usable boot sector!

billdeg
September 17th, 2013, 06:22 AM
I am wondering if these are my Televideo disks (copies of)..I mailed a copy of the 802 disks to someone once (don't remember it was a long time ago) and I asked the person to return them to me and image for others to use in the future. I'd suggest you try to make another set of boot disks, using slightly different image disk parameters. See what happens. Another approach would be to find 803 or close enough OS disks and see if those work.

jharre
September 17th, 2013, 06:50 AM
Chuckster-in-Jax: It is reassuring to know that this isn't one of those, "wow, never seen that before!", type problems. Did that TS-802H image work for you? If so, would you be willing to make a copy?

I think somewhere in the docs it mentioned that one of the switches in the back tells the 802H whether to boot from floppy or HD. Once booted it should be fairly easy to build a plain 802 boot disk.

Jim

jharre
September 17th, 2013, 07:24 AM
There is an image of CP/M 2.2 for the TS-803 on the bitsavers site. I'll try that and see what happens.

Chuck(G)
September 17th, 2013, 08:09 AM
I've got an 802H boot in my collection; I suspect that the Maslin collection does also.

acollins22
September 17th, 2013, 09:06 AM
Hi,

I too have that problem with my TS-802 so you're not alone.

My machine came without floppy drives but with disks that I was told were booting the machine until the drives were taken for another project. I dropped in a couple of half hight drives I found and now I get the same problem as you.

If I try removing the drives I get a fault message and with the drives in an unending trail of dots.

My machine is packed away at the moment but IIRC it did do a seek opn first power up but no sign of stepping after that. It's quite interesting to watch the diagnostic LEDs on the main board with and without a floppy drive connected.

Please keep us informed of how you get on. I'll do the same when I make some progress.


Cheers,

Andy.

jharre
September 17th, 2013, 09:42 AM
Thanks for that memory jogger, Chuck(G). I used to have the Don Maslin archive until MSE decided it was infected and took it upon itself to delete them for me (how nice!) I picked up a couple fresh images and a later version of IMD from DD's site and then retrieved the Maslin archive from Gaby's site. Looks like I will be doing a bunch of disk swapping after lunch.

Andy: with three of us now it looks like a "repeatable error" :)

billdeg
September 17th, 2013, 10:14 AM
The Maslin archive *is* infected with viruses, but not many and can be easily cleaned before use. You have to do a scan of the ZIP files within the ZIP file to locate and clean. At least the version I got when it first became available. I forget the virus name, it wasn't Stoned Monk, but nothing that can really hurt a modern PC.
bd

Chuck(G)
September 17th, 2013, 10:56 AM
In any case, a virus is unlikely to have infected a non-x86 system diskette.

Has anybody bothered to "dis-infect" the affected images from the Maslin archive? I suspect most are boot-sector viruses which can be taken care of easily by simply replacing the boot sector with a "clean" one.

billdeg
September 17th, 2013, 12:16 PM
I disinfected mine, but I did not want to upload such a large file to my server and deal with the bandwidth issues of everyone grabbing a copy. It's easy enough to dis-infect locally. Maybe whomever has the master copy will do this.

jharre
September 17th, 2013, 08:34 PM
Well it was an interesting, but frustrating afternoon. I installed the later version of IMD and re-made a couple disks. No luck. Made some new disks from images from the Dunfield site, still no luck. Grabbed two 802 images from the Maslin archive, reconstituted with TeleDisk, and still all I see is dots on the screen.

So, I replaced the floppy drive I'm using in the TS-802 with another known good drive - this time a Teac FD-55 - and achieved the same unspectacular results. Nothing but dots.

Tomorrow I hope to have time to fire up my ZetaSBC, attach the Teac drive and start reading to make sure there is data on track 0 of these imaged disks.

jharre
September 19th, 2013, 02:51 PM
I spent a little quality time with some disk utilities and found that the images do indeed appear to have boot code. While I didn't decode the machine language, it does seem fairly consistent among the different images. They all have Digital Research copyrights in the in the second sector of track zero and CP/M directories beginning in the first sector of track 2. So, it seems a rather safe bet that the disks built from images are good.

It seems unlikely that the floppy controller chip has failed in three similar computers. And, it is trying to do SOMETHING since it puts all the dots on the screen (the dots stop if you open the floppy door, so it seems an indication that something is going on).

What next?

Chuckster_in_Jax
September 19th, 2013, 03:11 PM
I'll dig my computer out this weekend and see if I have any better luck. Too tired right now to do anything with it.

billdeg
September 20th, 2013, 06:58 AM
I have an 80x drive, motherboard and the two drive controller cards here in front of me. How confident are you that the controllers are OK? THere are a lot of failure points in this hardware. Have you probed the controllers for standard signs of trouble?

Do you have HM jumpered on the disk drive?

billdeg
September 20th, 2013, 07:09 AM
I suppose while this stuff is out, pm me if anyone wants to make an offer for these items and I will paypal you an invoice and ship worldwide:

1 teac drive FD 55B-01-U
1 B900019-001 REV A motherboard
1 2017400 rev drive controller daughterboard
1 WDC b900010 001 rev F hd controller
1 set cables that connect these.

Shipping in a thin box, but large enough to allow for well padded items.

jharre
September 20th, 2013, 09:34 AM
Bill, the drive I'm using says: Teac FD-55BR 100-U on the back label. If there's an HM jumper, I sure can't find it. There are pads without stake pins for HS and HL. What does HM do? Head load with motor on? The heads are always loaded on this drive.

Not being a real hardware technician by any stretch of the imagination, what things should I be looking for on the controller card?

Chuckster - don't forget your weight-lifting belt. These suckers are heavy!

billdeg
September 20th, 2013, 09:55 AM
maybe it's an AM not an HM. Hard to read. These are the drive select jumpers:

MX
DS3
DS2
AM? [JUMP'R] (or HM?)
DS1
DS0 [JUMP'R]
HS

Chuck(G)
September 20th, 2013, 09:58 AM
FD-55BR = latch is on right side of drive.

HM, HS determine if the head is loaded (for those models with head-load solenoids) on receipt of the MOTOR ON or DRIVE SELECT signals respectively. Teac strongly advises against have both jumpered at the same time. For head-load solenoid-less drives, both jumpers should be open.

Manual here (http://bitsavers.trailing-edge.com/pdf/teac/10131159-00A_FD55_InstructionMan.pdf)

billdeg
September 20th, 2013, 10:03 AM
Not being a real hardware technician by any stretch of the imagination, what things should I be looking for on the controller card?



replace the 1793 chip on the drive controller (the small card directly attached to the mother board). That might be the entire problem.

jharre
September 20th, 2013, 11:59 AM
replace the 1793 chip on the drive controller (the small card directly attached to the mother board). That might be the entire problem.

Seems like a reasonable thing to do. Got a couple of those on order from ACP for $7 each.

Don't remember what I was paying for WD FDC chips back in the early to mid-80's, but it was a heck of a lot more than that.

jharre
September 20th, 2013, 01:43 PM
HM, HS determine if the head is loaded (for those models with head-load solenoids) on receipt of the MOTOR ON or DRIVE SELECT signals respectively. Teac strongly advises against have both jumpered at the same time. For head-load solenoid-less drives, both jumpers should be open.

The 55BR strapping is highly abbreviated from the manual in the link - there isn't an HM jumper:
15302

I just have the DS0 and FG jumpers plugged. (Dunno what FG does, "Feels Good"?)

Chuck(G)
September 20th, 2013, 08:23 PM
Look at PDF page 32 (Document page 229). You'll find your HM jumper there. Nobody said that Teac manuals are easy to read. Very often, several different models/PCBs are discussed in the same manual (you should see the wild assortment in the FD235 manual).

FG - frame ground. Jumpering it connects the power supply return to the metal frame of the drive. Sometimes used when the drive is installed in a non-conducting mounting. Otherwise, it probably doesn't matter.

jharre
September 20th, 2013, 08:38 PM
Look at PDF page 32 (Document page 229). You'll find your HM jumper there. Nobody said that Teac manuals are easy to read. Very often, several different models/PCBs are discussed in the same manual (you should see the wild assortment in the FD235 manual).

Yes, I saw that page - but the document is for a 55(L) and my 55B has a different arrangement as pictured in my attachment above. Teac probably had dozens of variations of their 48 tpi drives. It must have driven their tech document writers nuts.

Here's a photo of the board on my 55B with the jumpers:
15303

Chuck(G)
September 20th, 2013, 10:06 PM
Yup, I've got a pile of 5.25" Teac drives--55B, BR, F, FG and even a G; with HL solenoids and without. And I've got jumper docs FAXed by Teac tech support back in the day. Their jumper documentation usually didn't show the board layout--just the jumper names. So HM on any drive means the same thing. There was even a time that Teac would FAX you the drive schematic if you asked.

Teac changed their boards more often than some people change their underwear.

jharre
September 26th, 2013, 07:14 PM
Update: The replacement FDCs didn't solve anything.

I bought a pile of parts from billdeg (thanks, Bill!) that should arrive in a few days. Hopefully they will go a long way towards bringing this old CP/M machine back to life.

billdeg
September 26th, 2013, 08:13 PM
The items are on their way. I accidentally forgot to send a boot disk so I mailed you one separately the next day.