TI 99 Disk Controller question...

[eccofonic]

After several years in storage, I put back together a PEB. The flex cable card and 32k RAM card work fine, but the TI disk controller card....

 

When the card is accessed, the LED on the card stays lit and the computer hangs. Regardless of whether a drive is connected or not. Doesn't matter which slot I put it in either (I know it's supposed to be the closest one to the drive bay). I noticed the 5v regulator chip gets warm, but no other chips do, including the 12v regulator.

 

What would be the behavior of a known-working TI disk card if no drives were connected? Would it hang the computer or just generate an error and continue?

[ti99_forever]

It should generate an error, after a period of trying...

[eccofonic]

It should generate an error, after a period of trying...

It hangs for more than a minute... then I get nervous and turn it off.

 

Anybody out there know for sure or have a PEB box that could test?

[Willsy]

Try it without connecting the controller to the drives. What does it do?

[eccofonic]

Try it without connecting the controller to the drives. What does it do?

 

I said this in the first post...

 

Regardless of whether a drive is connected or not.

Edited July 24, 2014 by eccofonic

[CosmicBoy]

maybe the controller is ok and the drive is defect

Test the drive in a different computer .. maybe an old pc or something like that.

or use an other diskdrive

[marc.hull]

Your drive is not the issue. Sounds like the access to the DDR space is not going well.

 

Try resetting the flex card a couple of times as well as the console connector as a quick finger crossed fix. Also try the fdc by itself in the cage.

 

Same symptoms?

[Gary from OPA]

Test all power supply outputs from the PEB itself, even if the RS232 and 32K works, it could be the power supply is having issues.

 

I got five PEB's myself, and out of them 4 of them are having major issues with 12volt load when I got more then 3 cards in the cage, after 30 years of usage they are starting to die, and very rarely got turned off.

 

Might be time to convert them over to PC power supplies, and then convert over all the cards to use direct and remove 5 and 12 regulators.

[Stuart]

You say "When the card is accessed". Does the LED flash when you power on the console, and hangs when you then try to load or save? Or is it hanging when you power on the console?

[eccofonic]

You say "When the card is accessed". Does the LED flash when you power on the console, and hangs when you then try to load or save? Or is it hanging when you power on the console?

 

It hangs when I power on the console.

[Stuart]

 

It hangs when I power on the console.

Have you got a MiniMem cartridge, then you can check the DSR? You'll need to power on the console first, then the PEB. Then with the MiniMem cartridge you need the following (IIRC):

 

(1) From the MiniMem menu, select EasyBug.

(2) C 1100 1 <Return> [Floppy LED should light]

(3) M 4000 <Return><Space><Space>... [To read out memory]

 

Compare the data you're getting against this: http://nouspikel.group.shef.ac.uk/ti99/dc1.txt. If you see errors, then a common point of failure is the 74LS245 on the floppy card, which runs rather hot and has a bit of a hard time.

[eccofonic]

Have you got a MiniMem cartridge, then you can check the DSR? You'll need to power on the console first, then the PEB. Then with the MiniMem cartridge you need the following (IIRC):

 

(1) From the MiniMem menu, select EasyBug.

(2) C 1100 1 <Return> [Floppy LED should light]

(3) M 4000 <Return><Space><Space>... [To read out memory]

 

Compare the data you're getting against this: http://nouspikel.group.shef.ac.uk/ti99/dc1.txt. If you see errors, then a common point of failure is the 74LS245 on the floppy card, which runs rather hot and has a bit of a hard time.

 

I do have Minibug.

 

Unless my ROMs are completely different, I see these bits changed:

 

A4000-01 should be AA 02 but is AA 00

A4008-09 should be 40 4A but is 40 48

A4012-13 should be 5B 38 but is 58 38

A401A-1B should be 01 11 but is 01 10

A401C-1D should be 40 22 but is 45 22

A401E-1F should be 5B 52 but is 5A 50

A4020-21 should be 01 12 but is 01 10

A4022-23 should be 40 28 but is 40 29

A4024-25 should be 5B AC but is 5A AC

A4026-27 should be 01 13 but is 00 10

A402A-2B should be 5C 78 but is 58 78

A402C-2D should be 01 14 but is 00 14

A4034-35 should be 40 34 but is 40 38

 

many other random errors follow....

[Stuart]

 

I do have Minibug.

 

Unless my ROMs are completely different, I see these bits changed:

 

 

 

many other random errors follow....

 

If you take the floppy card apart, are the ROMs original? http://nouspikel.group.shef.ac.uk/ti99/fdcard.htm

 

Have you got other cards in the PEB that *do* work? That I think would rule out problems with the PEB power supply. Next I think I would replace the 5V regulator on the floppy card (because it's easy) then look at replacing the 74LS245.

[eccofonic]

 

If you take the floppy card apart, are the ROMs original? http://nouspikel.group.shef.ac.uk/ti99/fdcard.htm

 

Have you got other cards in the PEB that *do* work? That I think would rule out problems with the PEB power supply. Next I think I would replace the 5V regulator on the floppy card (because it's easy) then look at replacing the 74LS245.

 

Yes, the RAM card works... I type "SIZE" in extended basic and it gives me the extra RAM total.

 

The ROMs are labeled as follows:

 

1501392-33 C2E020 (and date code probably of 8303) this is the one closest to the FD1771 chip

1501392-34 C2E019 (8305)

[eccofonic]

Answering my own question here (for anyone who needs the info in the future)...

 

What would be the behavior of a known-working TI disk card if no drives were connected? Would it hang the computer or just generate an error and continue?

 

I got another card and it does not hang the system without a drive attached at boot up.

 

The card LED flickers quickly and then the TI logo screen comes up.

 

I used MiniMemory and looked at the DSR, and all bytes were the same as the listing in the "dc1.txt" file.

 

The card functions great with a Tandon TM100-2A I pulled out of an old IBM. I set it to DS0 with terminator IC installed, using a straight cable.

 

Formats single sided (90k) and double sided (180k) fine. I'm assuming no double density is available. I read the card doesn't support it.

Edited July 30, 2014 by eccofonic

[eccofonic]

LOL, more bad luck. Now that I can load programs from the internet (using TI99-PC)....

 

....any program loaded into my 32k RAM card is either corrupt when listed/run or crashes the computer.

 

Doesn't matter what slot it's put in. Contacts are clean on the card too.

 

Other programs/data that load off the disk into VDP RAM or cartridge RAM (i.e. Tunnels of Doom, Adventure, MiniMemory, etc) work fine.

 

Anyone out there have a spare 32k RAM card for sale or to give away?

Edited July 31, 2014 by eccofonic

[Willsy]

You could use Easy Bug in the Mini Mem cart to write data to the 32K and then read it back.

 

First, write a 0 to A000 then read it back. If not zero, a RAM IC is down.

 

Then try writing FFFF to A000 and read it back. If not FFFF a RAM IC is down.

 

Using the schematic, it would probably be possible to determine exactly which IC is broken then you could fix it up no problem.

 

Might also be worth changing the capacitors at the same time - can't remember if there's any liquid type (small canister) caps on the card, but if there are, they're 30 years old and *well* ripe for changing out by now!