From: see-sig@online.no   
      
   "ReptilesBlade"  wrote in message   
   news:1135049322_857@spool6-east.superfeed.net...   
   > Knut Roll-Lund  wrote in   
   > news:456dnSRZl44UxjreRVnzvA@telenor.com:   
   >   
   >> ReptilesBlade wrote:   
   >>> Knut Roll-Lund  wrote in   
   >>>   
   >>> Ok, I went to Best Buy today and got a new power supply. I figured out   
   >>> how to re-wire it so that it does not have to be plugged into a mobo to   
   >>> work thanks to Bill. I did just what you suggested there and it went   
   >>> down just as you said it would.   
   >>>   
   >>> That should mean that for all practical purposes once I get those 720k   
   >>> 3.5" disks from CN80 this upgrade will be finished. I cannot wait to   
   >>> get to transfer stuff from my Model 4 and my P4 and begin to really be   
   >>> able to use this thing!   
   >>   
   >> You can use 1.44MB HD disks by taping over the extra hole on the   
   >> underside, for testing (right side). The sensor is mechanical from the   
   >> underside.   
   >>   
   >> Using HD media is not recommended as there are differences, but I have   
   >> never had any problems not even over time (some years now). The spec is   
   >> close enough and the tweak is for lower density. Note this is 3.5"   
   >> specific. I never trust a single disk anyway: Allways backup!!!   
   >>   
   >>> On a side note I have discovered I kind of enjoy keeping an irregular   
   >>> diary with the Model 4 and anything I write on it is most certainly   
   >>> secure because I would be surprised if anyone else in my family could   
   >>> do anymore than just turn the system on and stare at the title screen   
   >>> lol! I would assume that the data would be safe from anyone unpleasant   
   >>> trying to access it as well because, to quote a news article I once   
   >>> read, "The TRS-80 uses a programming language today's geeks no longer   
   >>> speak".   
   >>>   
   >>> T'is a good day, perhaps once I get the disks and play with the thing a   
   >>> bit more I can focus on getting it on-line.   
   >>   
   >> Knut   
   >>   
   >   
   > What! Can you give me a pic showing this? Please?   
      
   I don't have a photo just now, sorry, but I'll elaborate on the description:   
      
   The drive has two small microswitches sensing the HD hole in the disk and   
   the writeprotect hole in the disk. The writeprotect hole has a slider and it   
   is on the left side of the disk. A DD disk has only the writeprotect hole.   
   The microswitches are mounted in the bottom of the drive and sense the   
   status when the disk is lowered onto them (inserted).   
      
   The difference between 3.5" DD and HD media is small. The most important   
   factor here is the corsivity, this is a measure of how powerful a magnetic   
   field should be to write the disk. This means a difference in the current   
   used in the magnetic head when writing. The drive adjust the difference   
   between HD and DD based on the hole.   
      
   3.5" DD is 720KB and HD is 1.44MB. (Note: Apple2 do 800KB on the same 3.5"   
   DD media)   
      
   The normal M4/4P can't do HD. DD is the maximum of the floppy controller.   
   Therefore we need to use DD media.   
      
   But since the HD and DD is so close you can cover the HD hole with tape and   
   the drive will think it is a DD media and use it as such.   
      
   The argument against this practice is that the write current is not high   
   enough and the bits written will be weak, and if they don't outright fail   
   they will fade. I have not experienced any problem with this, but you should   
   know it, that using HD media is not proper.   
      
   So if you want to do testing  you can use HD media if you have, while you   
   wait for DD media to arrive.   
      
   Knut   
      
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