Corcomp 9900 disk controller problems

[Stuart]

Yeh, I remember seeing that some time back, but the problem is as I turn on the system it locks. Now to be honest, I just realized that I am using a Corcomp Ramdisk at the same time, so I will take it out and try the rig. But the Ramdisk, or at least the 32k memory part of it works fine(tested with the Corcomp diagnostic cartridge), and the Call RAMGR function in its DSR is good, and I just formatted a MFM drive on the TI rig I am using with a HFDC installed, so I assume it's good. I was thinking maybe that either a PAL chip on Corcomp controller could be a problem or there are two chips, the MCM2114P SRAM and RCA CD4069UBE CMOS Hex inverter(don't know any thing about these chips), that I thought could be a problem. Or the 74LS123 chip(My tester does not have a listing for these and cannot identify it when it is plugged into the socket), but I haven't been able to search for a spare yet. Since I got my HFDC functional a couple of weeks ago, its priority has fallen. Still working on my cars till 9 or 10 at night, after work.

 

I believe the trick with Minimem works if you switch the console on first then switch the PEB on after.

[+InsaneMultitasker]

The Geneve EPROM does execute the powerup sequence during power up, even if the master DSR controls once the OS is loaded.

 

What other cards are in the system? Have you tried isolating the system to the CorComp FDC and a flex cable? And have you tried a different flex cable and/or console?

[RickyDean]

I read the manual and it said that there were two versions of the software, one for the older model and one for the newer one. It might just work, as I found references to the same software being used back as far as 2004. . .

Well, I tried the one that was on the site and it does not work with my Gangpro. So I will keep on looking, maybe I'll run across something, but I imagine that I will probably get another eprom programmer when money permits.

[+Ksarul]

Note: there are supposed to be two versions of the software in the package, one for the older model and one for the newer one. It still may not work, but at least its a possibility (unless your test was with the version for the older model, in which case, the test failed and I'll keep looking for you too).

[RickyDean]

Note: there are supposed to be two versions of the software in the package, one for the older model and one for the newer one. It still may not work, but at least its a possibility (unless your test was with the version for the older model, in which case, the test failed and I'll keep looking for you too).

I may have the wrong file then, the one I got was the following, didn't any options pop up;

GANGPRO 8 XP-w3 Winlnk 3 WINDOWS XP/7/8 Winlink3 v1.34.20 setup.exe

[+Ksarul]

The threads I saw indicated that you had to use a copy of Winlink (not Winlink2 or Winlink3) for the older ones. . .

[RickyDean]

The threads I saw indicated that you had to use a copy of Winlink (not Winlink2 or Winlink3) for the older ones. . .

I went to Google and input Winlink1 logical devices and got the following: http://www.logicaldevices.com/download2.htmThe one there on line 12 gave me the following: 404(Page not found) Error msg, but the one on 13 did allow me to download Winlink1, so I will try it tonight. Well I just went back to 12 and clicked on the name of the unit ,not the file name and I am getting a file called w133.exe. So maybe one or the other will work.

Edited January 18, 2016 by RickyDean

[RickyDean]

The threads I saw indicated that you had to use a copy of Winlink (not Winlink2 or Winlink3) for the older ones. . .

Well, thanks for your help Ksarul, that didn't work either though, Winlink 1 just says cannot connect to programmer, as does Winlink 2 (w133). Winlink 3 says programmer not responding when used with a straight cable and as I can't find my null modem, I tried something called a modem eliminator and also the TI crossover, I built years ago, and it also says can't connect. I played around with the comm port setting to no avail, but without a manual and/or the correct software, I'm stuck. I'm thinking it may have used Dos based software, but maybe it is still a cable/settings issue. Thanks again.

[ralphb]

I also have a non-working Corcomp controller here, revision C with WD2793A. It does load the CC Disk Manager from disk (potentially corrupted), but I can't do anything useful with it. CCDM, DM2 and even plain BASIC crash when trying to catalog a disk. Also, Extended BASIC crashes when it tries to auto-load DSK1.LOAD, even when there is no disk in the drive at all.

 

After some trial and error, my best bet would be to try the MG upgrade, which schmitzi thankfully provided. But looking at the files I noticed that the BINs are 2x16K instead of 2x8K. How is that supposed to work? I know that the original HN482764P has one pin not connected -- does the CC board wire that to A13? Are the original CC dumps available somewhere?

 

And on the backside of my board there's a small 4Kbit SRAM wedged between the two ROM banks, with WE attached to the TMS9901. I could see the need for storing data outside the TI memory, but why has this been added like an afterthought?

[atrax27407]

The MG upgrade is a set of two 8K EPROMs which I have and can burn. I also have the originals. They are both a direct plug-in to the sockets on the card.

[ralphb]

The MG upgrade is a set of two 8K EPROMs which I have and can burn. I also have the originals. They are both a direct plug-in to the sockets on the card.

 

Could you post or PM those files, in particular the original set? I have some EEPROMs left so I could do a quick test ...

[ralphb]

OK, I re-tried with a good EPROM set, but it still doesn't work properly. Extended BASIC always starts with error "NO PROGRAM PRESENT", DM2 and DM1000 crash when trying to catalog or format a disk.

 

Would anyone know of a way to test if the WD2793A is working properly?

[+Ksarul]

I would suggest replacing the 9901 first. . .as that is almost always the first chip to go on a CorComp card.

[justacruzr2]

Hi everyone. I'm going to jump in on this topic since I have a related problem. I recognize some of your handles from when I was last on the Yahoo TI 99/4A users group site. It's been 2 years since then and though I was distracted with other pressing things, I'm now back to trying to repair a CorComp 9900 disk controller card I bought from a fellow member. This one is an early model that is marked "Cor Comp Inc - PEB-DCC - 200002 H" and it's previous history is unknown. The seller had told me that it had an overheating problem at the voltage regulator and after a minute or 2 the card would lock up. I have confirmed the overheating problem simply by touching the voltage regulator when powered on. It gets hot like the steering wheel of a car that's been sitting in the summer sun for hours. That seems excessive. Anyway, I have replaced everything on that card with new parts with the exception of the floppy drive cable connector (seems unnecessary), the trim cap (my local electronics expert highly doubts that would cause the problem), the 8 postion DIP selector (for changing drive seek times) and the crystal. Also have not changed the diodes yet. I have them off the board but need to find a strong magnifying glass to be able to read the part numbers. So far nothing I've done has corrected the problem so I'm hoping this does the trick. I did compare the card to a picture of one sent me by another member and all the IC numbers check out as do all the other components. Did this in case someone had tampered with it before and installed incorrect parts. Seems like the solder side of the board has many variations though from pictures I've seen so it's hard to confirm if what's on mine is correct. There are about 3 mods that I see but they all look like CorComp mods. I have also confirmed the voltage at the PEB card connector (pin 2) at 8 volts and the output voltage at the regulator at 4.75 volts. That seems within tolerance. The CorComp menu screen does come up at power-up and I can go back and forth between menu selections a few times before the LED gets dimmer and finally goes out and it locks up. Assuming this is a built in protection of the voltage regulator when it exceeds heat tolerance. I have also checked the card using a different slot in the PEB but no change. The other cards in the PEB work fine and their regulators are not getting HOT....just normal warmth. Anyway, if the new diodes don't take care of this I guess I can undo the mods one at a time and see if that makes any difference. They look like CorComp mods but maybe they're not? I remember all sorts of mods for things in Micropendium and maybe there were some for the CorComp 9900? Would appreciate any suggestions from other users who have had this type of experience with the early CorComp 9900 and what they found.

I also have a revision A CorComp 9900 that I'm trying to repair. This one I bought originally and know it's full history. Problem with this one is it took a static charge hit. I have replaced all the IC's on it too except for the PAL12L6's which I know were trashed by the static. I substituted the PAL's from the early version and it does respond a little better but still no menu screen. Does anyone know if the algorythms burned onto these PALs were different between the early version card and the revision A card? I also have not replaced the other various electronic components on this board yet but do have the parts to do so. Just taking it one step at a time. Any thought on this appreciated as well.

Really need to get these cards working as all my floppies are DSDD and a TI DCC will not be able to read them.

And if Hal Shanafeld is reading this, could you please contact me? I would like to know the meeting schedule of the CTIUG. Thanks.

[Stuart]

The overheating card - are all the chips socketed? I'd be inclined to remove them all and see how hot the voltage regulator then gets (it shouldn't). Would also expect the voltage to be nearer 5V. If all OK with the chips removed, try replacing them one by one and see if a particular chip is causing the problem.

[justacruzr2]

The overheating card - are all the chips socketed? I'd be inclined to remove them all and see how hot the voltage regulator then gets (it shouldn't). Would also expect the voltage to be nearer 5V. If all OK with the chips removed, try replacing them one by one and see if a particular chip is causing the problem.

Hi Stuart. Socketing the few remaining chips that weren't originally was part of what I did while working on this card. So I can do that and that's a good suggestion. Something on this card is making the volt reg work harder than it should (at least that's my theory). Also occurred to me that whatever happened to this card may have damaged the crystal so that instead of not working at all...it's clocking faster than it should. I'm no electronics expert but I have read about people who overclock CPU's (non-TI) to increase the processing speed and one of their cautions is to install a better (larger) cooling fan. Makes me wonder if something similar is happening here? Anyway I'm going to try your suggestion and see what happens. Thanks.

[RickyDean]

Hi everyone. I'm going to jump in on this topic since I have a related problem. I recognize some of your handles from when I was last on the Yahoo TI 99/4A users group site. It's been 2 years since then and though I was distracted with other pressing things, I'm now back to trying to repair a CorComp 9900 disk controller card I bought from a fellow member. This one is an early model that is marked "Cor Comp Inc - PEB-DCC - 200002 H" and it's previous history is unknown. The seller had told me that it had an overheating problem at the voltage regulator and after a minute or 2 the card would lock up. I have confirmed the overheating problem simply by touching the voltage regulator when powered on. It gets hot like the steering wheel of a car that's been sitting in the summer sun for hours. That seems excessive. Anyway, I have replaced everything on that card with new parts with the exception of the floppy drive cable connector (seems unnecessary), the trim cap (my local electronics expert highly doubts that would cause the problem), the 8 postion DIP selector (for changing drive seek times) and the crystal. Also have not changed the diodes yet. I have them off the board but need to find a strong magnifying glass to be able to read the part numbers. So far nothing I've done has corrected the problem so I'm hoping this does the trick. I did compare the card to a picture of one sent me by another member and all the IC numbers check out as do all the other components. Did this in case someone had tampered with it before and installed incorrect parts. Seems like the solder side of the board has many variations though from pictures I've seen so it's hard to confirm if what's on mine is correct. There are about 3 mods that I see but they all look like CorComp mods. I have also confirmed the voltage at the PEB card connector (pin 2) at 8 volts and the output voltage at the regulator at 4.75 volts. That seems within tolerance. The CorComp menu screen does come up at power-up and I can go back and forth between menu selections a few times before the LED gets dimmer and finally goes out and it locks up. Assuming this is a built in protection of the voltage regulator when it exceeds heat tolerance. I have also checked the card using a different slot in the PEB but no change. The other cards in the PEB work fine and their regulators are not getting HOT....just normal warmth. Anyway, if the new diodes don't take care of this I guess I can undo the mods one at a time and see if that makes any difference. They look like CorComp mods but maybe they're not? I remember all sorts of mods for things in Micropendium and maybe there were some for the CorComp 9900? Would appreciate any suggestions from other users who have had this type of experience with the early CorComp 9900 and what they found.

 

I also have a revision A CorComp 9900 that I'm trying to repair. This one I bought originally and know it's full history. Problem with this one is it took a static charge hit. I have replaced all the IC's on it too except for the PAL12L6's which I know were trashed by the static. I substituted the PAL's from the early version and it does respond a little better but still no menu screen. Does anyone know if the algorythms burned onto these PALs were different between the early version card and the revision A card? I also have not replaced the other various electronic components on this board yet but do have the parts to do so. Just taking it one step at a time. Any thought on this appreciated as well.

 

Really need to get these cards working as all my floppies are DSDD and a TI DCC will not be able to read them.

 

And if Hal Shanafeld is reading this, could you please contact me? I would like to know the meeting schedule of the CTIUG. Thanks.

You know last week, my 9900 also started showing some kanji like characters and then all I got was a Cyan screen. I pulled the unit apart, tested all the logic chips, changed the 9901 and pulled the 9902's, left off the Disk controller board and same problem. I am suspecting the PAL or the ROM. Can anyone reproduction the PAL chip. Want to get mine operational again too.

[justacruzr2]

You know last week, my 9900 also started showing some kanji like characters and then all I got was a Cyan screen. I pulled the unit apart, tested all the logic chips, changed the 9901 and pulled the 9902's, left off the Disk controller board and same problem. I am suspecting the PAL or the ROM. Can anyone reproduction the PAL chip. Want to get mine operational again too.

 

Are you sure they're 9902's? Those IC's are UART's and are generally used on the RS232 board. More likely the PALs are at fault. They're very sensitive to any spikes or surges since the card has no electrical buffering. I would also like to find someone who can burn new PALs. My REV A 9900 will need them. Last week someone on eBay was selling a new lot of 5 PAL12L6's for $22.00. Before I could get back to them someone snagged them. The PAL's aren't much good unless you can find someone who can read the code from a good one and then burn it onto a new one. Trying to get in touch with the CTIUG 'cause I'll bet someone in the group still has an eprommer. Problem with CorComp was they were never very forthcoming about details of their card. They could have released that info to the TI community when they went out of business. Would love to see a schematic of the 9900 card and/or the equations that were burned onto the PALs. It also might be possible to contact W.R. Moseid for some info. He was one of the CorComp team. Only other way I can think of is to borrow a couple from a good 9900 and copy them. Also hope some more come up on eBay

[RickyDean]

 

Are you sure they're 9902's? Those IC's are UART's and are generally used on the RS232 board. More likely the PALs are at fault. They're very sensitive to any spikes or surges since the card has no electrical buffering. I would also like to find someone who can burn new PALs. My REV A 9900 will need them. Last week someone on eBay was selling a new lot of 5 PAL12L6's for $22.00. Before I could get back to them someone snagged them. The PAL's aren't much good unless you can find someone who can read the code from a good one and then burn it onto a new one. Trying to get in touch with the CTIUG 'cause I'll bet someone in the group still has an eprommer. Problem with CorComp was they were never very forthcoming about details of their card. They could have released that info to the TI community when they went out of business. Would love to see a schematic of the 9900 card and/or the equations that were burned onto the PALs. It also might be possible to contact W.R. Moseid for some info. He was one of the CorComp team. Only other way I can think of is to borrow a couple from a good 9900 and copy them. Also hope some more come up on eBay

Yes, the power plugs into the 9900 Micro Expansion system (should have clarified that) through the RS232 portion and the system could be purchased as a RS232 only system, and the disk controller could be purchased and added later, if I understand correctly. This means that without the disk controller addon, which also houses the 32k memory portion, you still had 9902's (two of them), (1) 1489, (2) 1488, (1) 9901, (1) 74LS123, (1) PAL, (1) Eprom ( I believe a 27128 series), (1) 74LS2244, (1) 74LS04, the system should still boot. But all I get is the cyan screen. Now I haven't checked the resistors and caps as of yet, but I am still leaning to the PAL as the culprit, as I have checked and/or changed all the 74 series chips, and have swapped out the 9901, and removed the 9902's and each of the other chips and retested, no difference.. On a side note and as stated in the beginning of this thread, my Corcomp disk controller card can be used but only with the Geneve, and a member of this forum already sold me a replacement set of the Miller Graphic eproms, that would not even let the Geneve use the card. I had to go back to the old MG set. The PAL is what I was suspecting on this one too, and your words have strengthened that, though not conclusively.

Edited June 1, 2016 by RickyDean

[+acadiel]

 

Are you sure they're 9902's? Those IC's are UART's and are generally used on the RS232 board. More likely the PALs are at fault. They're very sensitive to any spikes or surges since the card has no electrical buffering. I would also like to find someone who can burn new PALs. My REV A 9900 will need them. Last week someone on eBay was selling a new lot of 5 PAL12L6's for $22.00. Before I could get back to them someone snagged them. The PAL's aren't much good unless you can find someone who can read the code from a good one and then burn it onto a new one. Trying to get in touch with the CTIUG 'cause I'll bet someone in the group still has an eprommer. Problem with CorComp was they were never very forthcoming about details of their card. They could have released that info to the TI community when they went out of business. Would love to see a schematic of the 9900 card and/or the equations that were burned onto the PALs. It also might be possible to contact W.R. Moseid for some info. He was one of the CorComp team. Only other way I can think of is to borrow a couple from a good 9900 and copy them. Also hope some more come up on eBay

 

 

And hope they didn't blow the fuses that keep you from reading the PALs......

[justacruzr2]

Yes, the power plugs into the 9900 Micro Expansion system (should have clarified that) through the RS232 portion and the system could be purchased as a RS232 only system, and the disk controller could be purchased and added later, if I understand correctly. This means that without the disk controller addon, which also houses the 32k memory portion, you still had 9902's (two of them), (1) 1489, (2) 1488, (1) 9901, (1) 74LS123, (1) PAL, (1) Eprom ( I believe a 27128 series), (1) 74LS2244, (1) 74LS04, the system should still boot. But all I get is the cyan screen. Now I haven't checked the resistors and caps as of yet, but I am still leaning to the PAL as the culprit, as I have checked and/or changed all the 74 series chips, and have swapped out the 9901, and removed the 9902's and each of the other chips and retested, no difference.. On a side note and as stated in the beginning of this thread, my Corcomp disk controller card can be used but only with the Geneve, and a member of this forum already sold me a replacement set of the Miller Graphic eproms, that would not even let the Geneve use the card. I had to go back to the old MG set. The PAL is what I was suspecting on this one too, and your words have strengthened that, though not conclusively.

 

Aahh. Didn't know that what you were working with was the Micro Expansion System. And yes. That system was designed to be added to. You could start out with just the 32K and add more functionality later. I believe it all daisy-chained if I remember correctly.. On my Rev A card the PALs are definitely part of the problem. When I power up it just makes a racket (loud buzzing and the screen goes berserk). When I put the PALs from the early version card on it (those ones are good) no buzzing or berserk screen but I still don't get any display on the screen so there is more wrong than just the PALs. The only thing I don't know is whether the early version card PALs have the same thing burned on them as the Rev a card PALs.

[RickyDean]

 

Are you sure they're 9902's? Those IC's are UART's and are generally used on the RS232 board. More likely the PALs are at fault. They're very sensitive to any spikes or surges since the card has no electrical buffering. I would also like to find someone who can burn new PALs. My REV A 9900 will need them. Last week someone on eBay was selling a new lot of 5 PAL12L6's for $22.00. Before I could get back to them someone snagged them. The PAL's aren't much good unless you can find someone who can read the code from a good one and then burn it onto a new one. Trying to get in touch with the CTIUG 'cause I'll bet someone in the group still has an eprommer. Problem with CorComp was they were never very forthcoming about details of their card. They could have released that info to the TI community when they went out of business. Would love to see a schematic of the 9900 card and/or the equations that were burned onto the PALs. It also might be possible to contact W.R. Moseid for some info. He was one of the CorComp team. Only other way I can think of is to borrow a couple from a good 9900 and copy them. Also hope some more come up on eBay

Does anyone happen to know how to get ahold of the gentleman mentioned here,W.R. Moseid, or another way to get copies of the PAL's? Even if another chip has to be used with a patch board piggy backed in the original PAL socket on these cards. We really need to start getting together a collection of PAL's, GAL's and whatever else is needed to keep our hobby going, especially on the Corcomp, both PEB card and micro expansion system.

[justacruzr2]

Does anyone happen to know how to get ahold of the gentleman mentioned here,W.R. Moseid, or another way to get copies of the PAL's? Even if another chip has to be used with a patch board piggy backed in the original PAL socket on these cards. We really need to start getting together a collection of PAL's, GAL's and whatever else is needed to keep our hobby going, especially on the Corcomp, both PEB card and micro expansion system.

 

Although I haven't, as yet, tried to contact him, I was going to start with a Google search. He might have a Facebook account or something like that. Agree that we need to do something with CorComp products. As for the PALs, 12L6's are not the only thing that will work. Take a look at the picture of the Rev A card I found on the internet. It has PAL's with a different number on them. So I guess there's more than one choice for an IC. If someone would be kind enough to allow someone to copy their PALs that would be a good start.

[RickyDean]

 

Although I haven't, as yet, tried to contact him, I was going to start with a Google search. He might have a Facebook account or something like that. Agree that we need to do something with CorComp products. As for the PALs, 12L6's are not the only thing that will work. Take a look at the picture of the Rev A card I found on the internet. It has PAL's with a different number on them. So I guess there's more than one choice for an IC. If someone would be kind enough to allow someone to copy their PALs that would be a good start.CorComp Rev A disk controller card.jpg

I will take a couple of pictures of my Micro Expansion boards this weekend(have the box apart till I get it functional again) and I may already have posted a picture of my 9900 PEB card somewhere here on the forum, will search and post here. Found this at mainbyte, same as mine.

Edited June 3, 2016 by RickyDean

[justacruzr2]

I will take a couple of pictures of my Micro Expansion boards this weekend(have the box apart till I get it functional again) and I may already have posted a picture of my 9900 PEB card somewhere here on the forum, will search and post here. Found this at mainbyte, same as mine.

 

Thanks for posting those pictures, especially the early model CC9900 card. The picture I have is low-res and when you zoom in, it just gets pixelated and you can't read the chip numbers. I see on that card there are jumpers on the two 3-pin blocks in the upper left hand corner next to the ROMs. Mine only has one jumper on the lower pin block and it is connecting the middle and lower pins...that one is connecting the middle and upper pins. Wonder if that is just for testing or is mine missing a jumper and also connected wrong? Testing will only tell. Would need to find another jumper. The way mine is jumpered is like the picture I found so I assumed it was right. Maybe not. The early card also has several single pin jumper blocks which I am assuming are for testing, diagnosing and adjustment (of the trim pots) purposes. I'm going to recheck my card by comparing it with the picture you supplied to see if there is anything else amiss.

 

Anyway a bit of good news. Both my cards (early and Rev A) now display the CC menu screen at power up and do work for about 1 minute before both LEDs get dimmer, go out and the system locks up with the voltage regulator getting very hot. I'm thinking that the problem is the same on both and that it's the PALs. I suppose that even though both PALs are electrically active (if they were burned out the menu screen wouldn't even come up at all) what happened could have scrambled what is burned on them and they might be working incorrectly. Unfortunately the only way to confirm this is with known good ones and right now I have no idea where they might come from.

 

Here's another interesting thing. There's someone on eBay right now selling a loaded PEB for $500. It has the 32K card and the CC9900 controller card and 2 1/2 height floppies. They say it has been tested (for 2 hours) and is working perfectly. That's a little too much just to get the CC9900 but isn't that bad if you need everything. Here's the link if your interested:

 

http://www.ebay.com/itm/TI-99-4A-TI99-Peripheral-Expansion-Box-System-DUAL-DS-DD-Disk-Drives-CORCOMP-/371644793321?hash=item5687c181e9:g:~3MAAOSwnNBXT5es

 

Still trying to find out when the Chicago TI Users Group (CTIUG) has its monthly meetings. I've been told that they give away something at every meeting (donated equipment). I live in the Chicago area so it wouldn't be a problem attending. I used to be a member anyway. Would be great to be at the meeting that they gave away a CC9900. Or at least maybe I could find out a way to get good PALs for mine.

 

One last thing. That picture of the CC9900 you have posted. Is it yours? If it is could you please take a picture of the reverse side (solder side of the board) and post it in a message? I would like to compare it with mine. There are some mods on the back of mine that look like they are CC mods but I would like to confirm this. Appreciate it if you can and Thanks.