Jump to content
Diecrusher

Troubleshooting P-Code card

Recommended Posts

I just installed a p-code card that I had purchased awhile ago.

 

When the card is switched off the TI boots fine. When switched on, the p-code card's led stays lit solid and I get a continuous tone (beep) through the monitor speaker. Tried pulling most of my other cards in the PEB and in made no difference.

 

I have not yet pulled the clamshell off of the card to check it out but I wanted to see if there's any suggestions to try first.

Edited by Diecrusher

Share this post


Link to post
Share on other sites

I just installed a p-code card that I had purchased awhile ago.

 

When the card is switched off the TI boots fine. When switched on, the p-code card's led stays lit solid and I get a continuous tone (beep) through the monitor speaker. Tried pulling most of my other cards in the PEB and in made no difference.

 

I have not yet pulled the clamshell off of the card to check it out but I wanted to see if there's any suggestions to try first.

 

There is a fix for early design's that is missing a diode, I think it was.

 

I have the exact same problem with one of my P-Code cards. One has the diode, the other does not. The one with, works, and the one without does not.

 

I stumbled across a Ryte-Data (I think) article on the fix. Maybe someone else here can expand on my foggy memory.

 

Cheers!

  • Like 1

Share this post


Link to post
Share on other sites

I just installed a p-code card that I had purchased awhile ago.

 

When the card is switched off the TI boots fine. When switched on, the p-code card's led stays lit solid and I get a continuous tone (beep) through the monitor speaker. Tried pulling most of my other cards in the PEB and in made no difference.

 

I have not yet pulled the clamshell off of the card to check it out but I wanted to see if there's any suggestions to try first.

 

If I recall correctly, this is normal behavior for the P-CODE card. It is looking for the Editor/Filer disk. You will need these disk to load the P-Code system.

 

I think it is in the development resources thread.

 

HERE

Share this post


Link to post
Share on other sites

Here's a section from the official TI Manual:

 

1.1.2 Testing the P-Code Card

1. The Power switch is located on the front of the Peripheral Expansion System in the lower left-hand corner. Turn on the peripheral system, monitor, and console in that order.

2. A light should briefly come on in the position where you have inserted the P-Code Card. Each time the computer system accesses the P-Code Card, its corresponding light comes on. Note that the intensity and duration of the light varies, depending on the operation being performed within the system

3. The p-System now beings its power-up sequence which requires 30-60 seconds. You will hear six beeps. The first beep indicates that the console is turned on. The second beep indicates that the interpreter is initializing. The third beep indicates that the System is initializing. The next three beeps indicate that the screen and keyboard are initializing. The "Welcome to UCSD p-System" title screen and the p-System promptline appear on the display.

4. If the light does not come on or if the System title screen does not appear, the corresponding card may not be properly inserted. Repeat the "Set-up Instructions" procedure. If you still have difficulty, see "In Case of Difficulty" on page 19.

  • Like 1

Share this post


Link to post
Share on other sites

And here's the article I was referring to with regard to the diode issue. It was found in the "Best of the Newsletters Volume 1". I don't remember where I obtained that document.

 

----------------------------------------

P-CODE CARD: POP GOES THE DIODE!

This article was taken, in full, from the 99/4 Users Of America, May, 1984 Newsletter.

We have found a 100% failure rate on the P-Code cards manufactured the fifty-second week of 1982. The card self-destructs whether you use it or not! As long as it is plugged into the peripheral cabinent it draws power, even though it may be turned off. This is due to a factory defective diode that does not allow current to drain off properly. If you have a P-Code card that has popped its cork, don't take it to your friendly exchange center and shell out $42 for a new one! Call TI CARES and request a new card! You don't have to pay for factory blunders, oversights, or what ever. The new cards have a germanium diode in them that corrects the problem.

----------------------------------------

 

 

Has anyone else ever heard of this issue? I can confirm that I have a 52nd week card, and the problem.

 

Maybe we just need to call TI-CARES. :lol:

 

  • Like 2

Share this post


Link to post
Share on other sites

You don't need any disks to start the p-code card. You can't do too much without them, but the card should still start. So this is some hardware error on the card.

The only extra thing required to start it is the 32 K RAM expansion.

  • Like 1

Share this post


Link to post
Share on other sites

I forgot to mention that if you get the "TI 99/4A SOFTWARE TEST SYSTEM" for the mini-memory cartridge, there is a P-Code test program in there. I don't have the disk image handy, but I know it's on WHTech.

 

I think it only tests the GROM's, but it's a start. For the record, my bad card, passes the GROM tests. :?

  • Like 1

Share this post


Link to post
Share on other sites

Ok, found the disk images. Attached are the three disks and I've converted 0290B, the instructions, to a PDF.

 

Disk Image 0290B.DSK are the Doc's

Disk Image 0291A.DSK Disk 1 (TI-Diagnostics)

Disk Image 0291B.DSK Disk 2 (TI-Diagnostics)

 

Some utilities run from Mini-Memory and others from Extended Basic.

 

Cheers!

 

0290B.DSK

0291A.DSK

0291B.DSK

TESTDOCS.pdf

  • Like 4

Share this post


Link to post
Share on other sites

Thanks for the all of the replies and the help.

 

I have looked at the p-code pcb and the is nothing obviously visibly wrong but I am digging further.

 

How do you determine the manufacture date of the card as mentioned above?

Share this post


Link to post
Share on other sites

I forgot to mention that if you get the "TI 99/4A SOFTWARE TEST SYSTEM" for the mini-memory cartridge, there is a P-Code test program in there. I don't have the disk image handy, but I know it's on WHTech.

 

I think it only tests the GROM's, but it's a start. For the record, my bad card, passes the GROM tests. :?

O290B.DSK you provided checks ROM 1, followed by Rom 2, followed by GROMs 1-8. I didn't see a note anywhere, but I do leave the P-Code Card disabled until a get a stable system ... then just before testing with the Mini-Memory cartridge, I slide the P-Code Card switch to on otherwise the diagnostics either won't work or they give spurious results. Just a heads up for anybody else using this test sequence.

Share this post


Link to post
Share on other sites

 

There is a fix for early design's that is missing a diode, I think it was.

 

I have the exact same problem with one of my P-Code cards. One has the diode, the other does not. The one with, works, and the one without does not.

I have both an ATA5282 (non-working) and an ATA2383. I was going to provide pictures, but I don't feel like disassembling both again.

My observations:

ATA5282 had a 9-pin SIP resistor network soldered to the B side of the 74LS245 (pulling each line about 480 ohms to + 5 volts). The ATA2383 had an 74HC245 in place of the 74LS245 and no SIP.

Now it is impossible to tell if the late 1982 one was repaired or if it was produced this way, but it struck me as odd. There is not a single diode any place on either PCB, so I guess I'm wondering "where" this missing one is supposed to be.

I had no tools beyond visual inspection and basic continuity in trying to diagnose the ATA5282 card until you provided the diagnostic disks in a later posting.

Before unsoldering the SIP/74LS245 cluster, the Mini-Memory, Test #1 would fail both ROMs and all GROMs. Once I had a socket in place, I put in an 74HC245 to match the ATA2383 PCB and re-ran the diagnostics. It now passes ROM 1 (4732), but still fails on ROM 2 and all GROMs.

I'm ordering an 8Kx8 prom (no 4764 direct equivalent) and when it arrives will depopulate ROM 2, re-socket and try again. Looking at http://www.mainbyte.com/ti99/schematic/p_code_card.jpg and all the common data lines affected, I'm really hoping it's ROM 2 and not any/all the GROMs.

I will keep the forum posted.

 

Doug

Share this post


Link to post
Share on other sites
On 1/15/2018 at 9:47 PM, helocast said:

I have both an ATA5282 (non-working) and an ATA2383. I was going to provide pictures, but I don't feel like disassembling both again.

My observations:

ATA5282 had a 9-pin SIP resistor network soldered to the B side of the 74LS245 (pulling each line about 480 ohms to + 5 volts). The ATA2383 had an 74HC245 in place of the 74LS245 and no SIP.

Now it is impossible to tell if the late 1982 one was repaired or if it was produced this way, but it struck me as odd. There is not a single diode any place on either PCB, so I guess I'm wondering "where" this missing one is supposed to be.

I had no tools beyond visual inspection and basic continuity in trying to diagnose the ATA5282 card until you provided the diagnostic disks in a later posting.

Before unsoldering the SIP/74LS245 cluster, the Mini-Memory, Test #1 would fail both ROMs and all GROMs. Once I had a socket in place, I put in an 74HC245 to match the ATA2383 PCB and re-ran the diagnostics. It now passes ROM 1 (4732), but still fails on ROM 2 and all GROMs.

I'm ordering an 8Kx8 prom (no 4764 direct equivalent) and when it arrives will depopulate ROM 2, re-socket and try again. Looking at http://www.mainbyte.com/ti99/schematic/p_code_card.jpg and all the common data lines affected, I'm really hoping it's ROM 2 and not any/all the GROMs.

I will keep the forum posted.

 

Doug

Get this working?

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...

  • Recently Browsing   0 members

    No registered users viewing this page.

×
×
  • Create New...