rlb@cs.odu.edu (Robert Lee Bailey) (03/21/89)
which detects the presence or absence of a hole to determine whether the media is 1.44M or 720K. Has anyone successfully modified their hardware and/or software to defeat this feature? (I use the term "FEATURE" with tongue in cheek!) I want to use cheap 3.5" diskettes at 1.44M, but, this asinine gimmick forces us to format to 720K. I know that some of you out there will say that using cheap disks in this manner is dangerous to the health of my data. To that I say: BAH! HUMBUG! I have SUCCESSFULLY used such disks on a PS/2 Model 50 for about a year now with ABSOLUTELY NO LOSS OF DATA regardless of how long the data has been there. The PS/2 drives apparently do not have the detection circuitry, but most clone drives do. It would seem that the manufacturers of diskette media are in cahoots with the manufacturers of 3.5" disk drives in order to try to force users to buy a hole for more than twice the price of no hole. (off soapbox) Anyway, I was wondering if anyone has come up with a successful work-around other than drilling (the chips WILL destroy the media and/or the drive itself) or melting (I don't like the smell) a hole in the strategic location? If not, does anyone have any technical info that details the pins and logic states for the detecting the hole? I am not opposed to installing a toggle switch to enable or disable the circuit. I just don't have the necessary info to do so. Help, info, or possible SOURCES of info would be appreciated. Bob Bailey
dkim@maui.cs.ucla.edu (Dong Hun Kim) (03/22/89)
In article <8168@xanth.cs.odu.edu> rlb@cs.odu.edu (Robert Lee Bailey) writes: >which detects the presence or absence of a hole to determine whether >the media is 1.44M or 720K. There is a small (tiny) pin which probes the hole. The pin is located at the lower right hand side inside the drive ( just below the hole ). If the pin is pressed (no hole) it recognizes the diskette as 720K, otherwise 1.44Mb. > Has anyone successfully modified their >hardware and/or software to defeat this feature? (I use the term >"FEATURE" with tongue in cheek!) I want to use cheap 3.5" diskettes >at 1.44M, but, this asinine gimmick forces us to format to 720K. > The pin is essentially a small switch, so you can bypass this switch by installing another small switch outside the drive. You can buy such a switch at any Radio Shack store. How to install the switch : - solder a pair of wires to the metal part at the base of the pin case; one wire at each side. one connects to (a) and one connects to (b) (see diagram below) - solder the wires to the switch you bought - drill the front bezel of the drive to install the switch, to make it accessible from outside. Tighten the switch screws. - Now, switch ON means high density (1.44), OFF means normal operation : if hole exist -> 1.44Mb if no hole -> 720Kb | | pin | a === | ==== b metal on the base | ===== sp ri ng ----- I implemented the above modification with very satisfactory results on Toshiba, Teac, and Sony drives. However, Sony drives are different from Toshiba and Teac. In Sony, if the two metals in the base in contact, it recognizes the diskette as 720K (the opposite of Teac and Toshiba). So, you must remove the pin and spring, etc. Now, ON -> 720K OFF -> 1.44M I hope that helps. Dong Kim dkim@ucla.cs.edu
tim@cit-vax.Caltech.Edu (Timothy L. Kay) (03/23/89)
In article <22063@shemp.CS.UCLA.EDU> dkim@cs.ucla.edu (Dong Hun Kim) writes: >How to install the switch : [...] If I trick my drive into writing 1.44M on a 720K disk, and then I give it to somebody who has not defeated the sensor in his drive, can he read the disk? (In other words, does DOS set the density for reading by looking at the hole, or just the density when formatting?) Tim
dts@cloud9.Stratus.COM (Daniel Senie) (03/24/89)
In article <8168@xanth.cs.odu.edu>, rlb@cs.odu.edu (Robert Lee Bailey) writes: > which detects the presence or absence of a hole to determine whether > the media is 1.44M or 720K. Has anyone successfully modified their > hardware and/or software to defeat this feature? (I use the term > "FEATURE" with tongue in cheek!) I want to use cheap 3.5" diskettes > at 1.44M, but, this asinine gimmick forces us to format to 720K. The Toshiba drive I bought has a jumper which, when removed, allows format of low density disks at high density. I have left this jumper FIRMLY in place. You have had good luck with a PS/2 Mod 50, but I had so many problems with this on PS/2 Mod 60s that I won't ever do it. Since I also have a 1.2MB 5.25 drive on this machine (which I use for backups) I don't need all that many 1.44MB disks. Fuji film and BASF are opening a very large plant in Lowell, MA to produce 3.5" floppies, so I expect the price will come down eventually. (Currently a large percentage of the disks are shipped from Japan). -- Daniel Senie UUCP: harvard!ulowell!cloud9!dts Stratus Computer, Inc. ARPA: anvil!cloud9!dts@harvard.harvard.edu 55 Fairbanks Blvd. CSRV: 74176,1347 Marlboro, MA 01752 TEL.: 508 - 460 - 2686
dkim@maui.cs.ucla.edu (Dong Hun Kim) (03/25/89)
In article <10121@cit-vax.Caltech.Edu> tim@cit-vax.UUCP (Timothy L. Kay) writes: >In article <22063@shemp.CS.UCLA.EDU> dkim@cs.ucla.edu (Dong Hun Kim) writes: >>How to install the switch : > [...] > >If I trick my drive into writing 1.44M on a 720K disk, and then I give >it to somebody who has not defeated the sensor in his drive, can he >read the disk? (In other words, does DOS set the density for reading >by looking at the hole, or just the density when formatting?) > >Tim This is a good point, which I forgot to mention in my previous posting. The answer is : NO, he will not be able to read it. Because his drive will still look for the hole, and if there is no hole, it assumes as 720K. EXCEPTION : IBM-PS/2 drive does not use probe, so it can format and read both densities. Dong Kim
erik@netcom.UUCP (16) (03/26/89)
In article <22063@shemp.CS.UCLA.EDU>, dkim@maui.cs.ucla.edu (Dong Hun Kim) writes: = In article <8168@xanth.cs.odu.edu> rlb@cs.odu.edu (Robert Lee Bailey) writes: = There is a small (tiny) pin which probes the hole. The pin is located = at the lower right hand side inside the drive ( just below the hole ). = If the pin is pressed (no hole) it recognizes the diskette as 720K, = otherwise 1.44Mb. = = > Has anyone successfully modified their = >hardware and/or software to defeat this feature? (I use the term = >"FEATURE" with tongue in cheek!) I want to use cheap 3.5" diskettes > >at 1.44M, but, this asinine gimmick forces us to format to 720K. = > =Modification procedure deleted] = > I implemented the above modification with very satisfactory > results on Toshiba, Teac, and Sony drives. I have a Toshiba ND-356T-A, FDD4603G0K, 1.44Mb drive. On the bottom of the drive Jumper B is used for density select, enable/disable of the function. If you wanted to install a switch you could just use a header on the pins. That way you could enable or disable the density select for use. Erik