+Ksarul Posted February 15, 2016 Share Posted February 15, 2016 Even in 1981, you only found Double Density disks. That is OK, as they work fine in single or double density. It is more important that you use double sided disks with double sided drives, as the disks certified back then as single sided often had lots of errors on the second side (and were thus much less than optimal). Bottom line: DD disks work fine. Quote Link to comment Share on other sites More sharing options...
LynxHandyCaster Posted February 15, 2016 Share Posted February 15, 2016 Even in 1981, you only found Double Density disks. That is OK, as they work fine in single or double density. It is more important that you use double sided disks with double sided drives, as the disks certified back then as single sided often had lots of errors on the second side (and were thus much less than optimal). Bottom line: DD disks work fine. My understanding: the problem is that the Disk Controller Card for the TI 99/4a PEB can only read/write single density floppies, even if the drive can read/write double density. Quote Link to comment Share on other sites More sharing options...
+mizapf Posted February 15, 2016 Share Posted February 15, 2016 My understanding: the problem is that the Disk Controller Card for the TI 99/4a PEB can only read/write single density floppies, even if the drive can read/write double density. You have to distinguish between the medium and the recording format. A medium that is certified for double density can be written as SD or DD. The TI disk controller card has a FD1771 controller on its board which is only capable of reading SD. But it cannot sense the quality of the medium. This is different for HD disks which have other magnetic properties. A SS/DD drive is unable to reliably magnetize the cells. 1 Quote Link to comment Share on other sites More sharing options...
+Ksarul Posted February 15, 2016 Share Posted February 15, 2016 Exactly--the drive is capable of Double Density, the floppy disk is capable of double density, but the controller will FORMAT the disks as single density if you are using the TI sidecar Disk Controller, the TI Single Density Card for the PEB, or the Percom Data sidecar Disk Controller. All other controllers (CorComp, Myarc, Atronic, BwG, ot the TI Double Density Card for the PEB) will instantly double the available capacity of both your drives and your blank floppy disks when you format them to Double Density. Single Density only puts data on half of the sectors on each track, with timing and other information on the in-between sectors. Double Density encodes a bit better, so it can use all of the available sectors on each track for data + timing, doubling the capacity. The physical disk doesn't care whether you are formatting single or double density--that is solely a function of what the controller is capable of and what you have selected (a double density controller can also format in single density). Quote Link to comment Share on other sites More sharing options...
LynxHandyCaster Posted February 15, 2016 Share Posted February 15, 2016 Exactly--the drive is capable of Double Density, the floppy disk is capable of double density, but the controller will FORMAT the disks as single density if you are using the TI sidecar Disk Controller, the TI Single Density Card for the PEB, or the Percom Data sidecar Disk Controller. All other controllers (CorComp, Myarc, Atronic, BwG, ot the TI Double Density Card for the PEB) will instantly double the available capacity of both your drives and your blank floppy disks when you format them to Double Density. Single Density only puts data on half of the sectors on each track, with timing and other information on the in-between sectors. Double Density encodes a bit better, so it can use all of the available sectors on each track for data + timing, doubling the capacity. The physical disk doesn't care whether you are formatting single or double density--that is solely a function of what the controller is capable of and what you have selected (a double density controller can also format in single density). Okay, understood. Thank you for clearing that bit about the floppy formatting up for me. Knowing what I now know, then I must have a problem with my half-height Epson 5 1/4" floppy drives. I was finally able to get the controller card in my PEB to recognize them; at least, I think that's correct. When I received the drives, no matter how I configured their connections with the card, the drive lights stayed on solid. Eventually, I found that the pins in the shunt pack of one of the drives were bent and touching each other. I straightened the pins out and the red lights on the drives no longer stay on solid; they flash as they should when I ask the Disk Controller Card (thru the Disk Manager 2 cartridge) to test them. But when doing a test or initialization thru the Disk Manager 2 cartridge, I still get a "DISK MANAGER ERROR 16," which means "NO DISK or NO DRIVE," even though I have a disk inserted. I've tested the drives (no floppy disks inserted) in Basic using the 2-line test program from the Controller manual; the drive light comes on briefly, and I get the "*I/O ERROR 06 IN 100" message as I should, therefore the drives are connected properly (according to the manual). Any ideas why I can't get either drive to be recognized through the Disk Manager 2 cartridge? Any help would be greatly appreciated. Thanks. Quote Link to comment Share on other sites More sharing options...
Omega-TI Posted February 15, 2016 Share Posted February 15, 2016 Are you aware of an insanely inexpensive modification for the TI floppy controller that will give you the same amount of storage space as a DS/DD 40 track controller card like the CorComp? If your drives are capable of 80 track, you'll be able to get 360K of storage space. << CLICK HERE >> for more information. Many of us have already performed, or have had this modification done. I might add, even if you need to buy new disk drives, like 3.5's and new mounting hardware, it's STILL cheaper than any rare DS/DD controller you may be lucky enough to run across. Quote Link to comment Share on other sites More sharing options...
+mizapf Posted February 15, 2016 Share Posted February 15, 2016 Single Density only puts data on half of the sectors on each track, with timing and other information on the in-between sectors. Double Density encodes a bit better, so it can use all of the available sectors on each track for data + timing, doubling the capacity. SD does write on all locations of a track. The difference is the encoding. SD uses FM encoding: Each 0 is encoded by "10", where "1" means flux reversal, "0" means same flux; each 1 is encoded as "11", which essentially means that the flux changes at double rate for 1 data bits compared to 0 data bits (hence Frequency Modulation). Double density uses MFM. The trick is to avoid flux reversals as often as possible. Each 0 is encoded as "x0" where "x" is 0 when the previously encoded data bit was 1, and 1 when the last bit was 0. Each 1 is encoded as "01". You can easily find out that there are never two subsequent "1" in the encoding; there is always at least one "0" in between. This again means that the flux reversal only occurs at half the rate, so you can afford to shorten the cell sizes from 4 microseconds to 2 microseconds without risking read errors by noise or bad medium. With 300 rpm, this means that you have 200ms rotation time, and hence 50000 cells on a track for SD, which yields (with 2 cells per data bit) 3125 byte per track, so at most 9 sectors plus sector headers, and 100000 cells for DD, which means 18 sectors. (part of my lecture ) 2 Quote Link to comment Share on other sites More sharing options...
+Ksarul Posted February 15, 2016 Share Posted February 15, 2016 Are you using a Floppy cable with a twist in it? That will cause issues. A TI Disk controller needs to have all wires straight through to all drives. At the drives, the first drive must have the jumper set to DS0 (This is actually drive 1). Some drives start their numbering at one, but the principle is the same--lowest drive number listed is drive one, and the next number above that is drive two (usually the DS1 jumper, when starting from zero). Also, only the last drive in the set should have a terminating shunt pack installed. Check these things and we may be able to get you to a solution. Quote Link to comment Share on other sites More sharing options...
LynxHandyCaster Posted February 15, 2016 Share Posted February 15, 2016 The last drive definitely has the termination resistance pack installed; I made sure of that. And I've checked the shunt pack jumper settings; disk drive one is set to DS0 and disk drive two is set to DS1. Quote Link to comment Share on other sites More sharing options...
+Schmitzi Posted February 16, 2016 Share Posted February 16, 2016 ...and a straight-through floppycable (no twist) as Ksarul asked ? (this smells for your prob, as leds were on) Quote Link to comment Share on other sites More sharing options...
LynxHandyCaster Posted February 16, 2016 Share Posted February 16, 2016 No twists in the ribbon. 1 Quote Link to comment Share on other sites More sharing options...
+Schmitzi Posted February 16, 2016 Share Posted February 16, 2016 uih, so maybe you have to test a one-drive-config now, with each of your drives, to find the error.Which Epson-drives are these ? sure that they "are" for the TI ? can you clean the heads ?Sure that both simltaneous do not consumpt too much power from the PEBs PSU ?Maybe you have one of the old TI-drives to check some more,i.e. that the controller and the rest is OK?... Quote Link to comment Share on other sites More sharing options...
TInaut Posted February 16, 2016 Share Posted February 16, 2016 No twists in the ribbon. Do you have the 5.25-inch floppy disk oriented correctly? There is a notch in one side of a (non-flippy) disk. If the disk is inserted into a horizontally mounted drive, the notch should face left or face right in the drive close to the front edge -- I.e., if you pull the disk out about an inch, you should see the notch. Similarly, if the drive is mounted vertically, the notch should face up or face down close to the front edge. Quote Link to comment Share on other sites More sharing options...
sparkdrummer Posted February 16, 2016 Share Posted February 16, 2016 Weren't the Epson drives power hungry? Have you ever had the present configuration working? I believe I would put one drive in the box with the proper termination and see if that works for you. Quote Link to comment Share on other sites More sharing options...
ckoba Posted February 16, 2016 Share Posted February 16, 2016 If you can't get it working with your Epson drive, I have two half-height drives that were pulled in working condition from a PEB. You can have them for shipping cost ... difficulty there is that I'm in Asia so it'd cost about USD$40 to get them to you. On the original topic: I was fairly certain until today that there was still a single US-based manufacturer of 5.25" floppies. Their primary (and perhaps only) customer was the US General Services Administration, because there's still a fair amount of critical gear painted green (and baby blue) that uses that media. Company name starts with an "A". Does that resonate with anyone, or am I time-displaced by a decade? 1 Quote Link to comment Share on other sites More sharing options...
RickyDean Posted February 16, 2016 Share Posted February 16, 2016 If you can't get it working with your Epson drive, I have two half-height drives that were pulled in working condition from a PEB. You can have them for shipping cost ... difficulty there is that I'm in Asia so it'd cost about USD$40 to get them to you. On the original topic: I was fairly certain until today that there was still a single US-based manufacturer of 5.25" floppies. Their primary (and perhaps only) customer was the US General Services Administration, because there's still a fair amount of critical gear painted green (and baby blue) that uses that media. Company name starts with an "A". Does that resonate with anyone, or am I time-displaced by a decade? I worked in Iraq and Afghanistan for almost 10 years and all I saw were 3.5 disks Quote Link to comment Share on other sites More sharing options...
+Schmitzi Posted February 16, 2016 Share Posted February 16, 2016 Weren't the Epson drives power hungry? Have you ever had the present configuration working? I believe I would put one drive in the box with the proper termination and see if that works for you. If these are "Epson SD521" they should work, 2 in the PEB (from one of my lists, but I have only this one Epson-drive listed) TI-99-4A-FLOPPIES-TI-99-v1.07.pdf 1 Quote Link to comment Share on other sites More sharing options...
ckoba Posted February 16, 2016 Share Posted February 16, 2016 I worked in Iraq and Afghanistan for almost 10 years and all I saw were 3.5 disks My EAOS was late nineties, and we had 5.25" gear that wasn't scheduled to EOL until mid-2000s (one YN was memorably using a Wang for something or other). Different branch, though, I suspect. Quote Link to comment Share on other sites More sharing options...
ralphb Posted February 16, 2016 Share Posted February 16, 2016 On the original topic: I was fairly certain until today that there was still a single US-based manufacturer of 5.25" floppies. I was under the impression that world-wide production of both 5,25" and 3,5" floppy disks, along with cassette tapes and VHS tapes, was halted some time ago. For cassette tapes I had to turn to ebay, only to discover that prices for still shrink-wrapped BASF brand cassettes are outrageous. Since then, I'm proudly wearing this shirt. 1 Quote Link to comment Share on other sites More sharing options...
LynxHandyCaster Posted February 16, 2016 Share Posted February 16, 2016 I appreciate very much everyone helping me to try and narrow down the problem with these drives. Here are answers to some of the questions that have come up: The drives were used when I bought them and I'm told by the seller that they worked but I'm not sure if he had them installed in a TI PEB. I haven't checked the model number of the drives, but I'll do that as soon as I get home from work today. I haven't checked to see if just one drive works by itself (the power capacity of 2 drives had not occurred to me), but I will try that also when I get home. And I don't have another drive to test the PEB or Disk Controller Card for problems. As both drives correctly light up individually when performing the tests with the Disk Manager 2 Cartridge, I wouldn't think that power overloading is the problem, though I'll grant you that each drive is probably only drawing power one at a time when I perform those tests. I'll be attending the Atlanta Historical Computing Society meeting this Saturday and I'll be bringing my entire TI system. I'm hoping someone there who is more knowledgeable about this kind of problem (by that I mean ANYONE) can help me get the drives going. In the meantime, if anyone here on the forum has any other troubleshooting ideas, please feel free to chime in. And thanks, again. MillipedeMan Quote Link to comment Share on other sites More sharing options...
atrax27407 Posted February 16, 2016 Share Posted February 16, 2016 Check eBay. There are bunches of them -even some in the original shrink-wrap package. Quote Link to comment Share on other sites More sharing options...
+Ksarul Posted February 16, 2016 Share Posted February 16, 2016 The vendor you are looking for is Athana. They still provide new 8" disks too. . .here's another source of 5.25 disks, though they look to be a reseller. Quote Link to comment Share on other sites More sharing options...
+Ksarul Posted February 16, 2016 Share Posted February 16, 2016 (edited) One note--it doesn't look like the Athana site has been updated in 15 years. . .but the company still exists, though at a different address (at least one phone number is the same). They appear to have four employees. . . Edited February 16, 2016 by Ksarul Quote Link to comment Share on other sites More sharing options...
LynxHandyCaster Posted February 17, 2016 Share Posted February 17, 2016 Both drives are identical Epson SD521 drives. And hooking just one of them up (with the termination resistance pack installed) resulted in the same error message when performing the test from the Disk Manager 2 Cartridge: "ERROR 16." And yes, I am putting the floppy disk into the drive the correct way. I've tried testing with and initializing other floppy disks that I have, both blank and already initialized (for the Atari 8-bit, but that shouldn't matter); same result every time. Of course all of them are labelled double density disks, but I'm now not sure if that matters. Thanks, and any other thoughts? Quote Link to comment Share on other sites More sharing options...
LynxHandyCaster Posted February 17, 2016 Share Posted February 17, 2016 (edited) The vendor you are looking for is Athana. They still provide new 8" disks too. . .here's another source of 5.25 disks, though they look to be a reseller. Both floppydisks.com and Athana have no SSSD 5.25" disks (if they ever even existed). Edited February 17, 2016 by MillipedeMan Quote Link to comment Share on other sites More sharing options...
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