******¢ DISKSAVR1.BAS DOCS!¢ The program is on this disk!¢¢ Ever copy a disk only to have the¢ routine choke on ONE bad sector? Well¢ DiskSaver! is the remedy! Works on¢ Sparta Sngl. or Enh. Density. Uses¢ direct disk access thru USR.¢ Allocates bad sectors in bit-map so¢ no data can be written to them.¢ Writes to the boot sectors so "DIR"¢ will show the correct amount of free¢ sectors. Will also fix disks that¢ show freespace greater than the whole¢ disk. Ever have that happen? I hope¢ you find this routine useful. Watch¢ for a dbl density version on: The REM¢ lab. The WeB BBs 24hr 7 days 708-884-¢ 0315¢ * DiskSaver! v1.0 (c) 1990 by REMlab¢ *************************************¢ First things first.¢ I got to looking at the pile of disks¢ I had that wouldn't format for one¢ reason or another and got to¢ wondering just how large that pile¢ was going to get before having to pay¢ extra rent. Then I started to wonder¢ just why those disks wouldn't format.¢ Using a sector editor, I discovered¢ that most of the disks had a bad¢ sector or two. Realizing that a box¢ of "cheap" disks cost as much as $6¢ retail, I would be throwing them away¢ to the tune of over $20.00. Yes, I¢ had a pile of over thirty disks that¢ wouldn't format correctly! So, I¢ decided to see if I could get ANY use¢ out of that pile.¢ I discovered that I could fix the¢ disks using a sector editor. This¢ required a great deal of typing to¢ write the boot sectors the way they¢ were intended.¢ Then I discovered I could fool the¢ editor by starting off with a¢ properly formatted blank disk,¢ reading the boot sectors, one at a¢ time, and swapping disks to write¢ those sectors to the "bad" disk.¢ Still alot of typing and time¢ consuming too. I wanted a routine¢ that I could just load and run and¢ let the machine do the work like it¢ was intended to do. No problem, just¢ read the boot sectors of a good disk¢ and write them to the bad one. It's¢ that easy. ¢¢ WRONG!!!!!!!!¢ You can't read the boot sectors like¢ you would a read a file! And even if¢ you could, what about the bad¢ sector/s? How do you prevent data¢ from being written to those sectors?¢ I thought of creating a file using¢ the bad sectors. But, then how would¢ I get DOS to write the file to those¢ particular sectors and if the file¢ ever got accidentally erased how¢ could DOS be prevented from writing¢ data to those sectors? ¢¢ Things seemed impossible and I was¢ about to give up when I was messing¢ with the sector editor again and¢ realized I might be able to allocate¢ sectors without having to create a¢ file that uses those sectors. It¢ worked! Now I had to find a way of¢ getting the machine to do all the¢ work so I wouldn't have to use the¢ editor sector by sector. I found a 49¢ byte USR routine in a BASIC utility¢ package I had laying around that¢ would allow direct access to the¢ disk, one sector at a time, and any¢ sector on the disk.¢ Using that USR routine I could read¢ each sector except the bad ones and a¢ simple error trap would branch to a¢ line that would tell me which sector¢ was bad.¢ Now came the hard part, changing the¢ sector map so DOS would skip the bad¢ sectors. I tried and tried until I¢ discovered that the sector map allows¢ for sector 0. SECTOR 0 DOESN'T¢ EXIST!!! But, it's in the sector¢ map!¢ Figure that one out! Okay, the sector¢ editor, then the USR routine,¢ allocate the bad sectors, a bad disk¢ becomes a good disk, right?¢¢ WRONG!!!!!!!!¢ I had a "fixed" disk and I started to¢ copy some files to that disk. I did a¢ "DIR" in the disk and guess what it¢ showed. 123 FREE SECTORS I tried to¢ copy one more file, a 121 sector¢ file.¢¢ ERROR 162!? How can that be? How¢ could I be so dumb? I forgot to¢ change the bytes that tell you how¢ many free sectors are on the disk. Oh¢ well, just remember that there are¢ fewer sectors on the disk than a¢ "DIR" shows.¢¢ WRONG!!!!!!!!¢ Finding the free sector bytes¢ required alot of trial and error. ie;¢ sector editor, change a byte, exit to¢ DOS, "DIR", wrong bytes, sector¢ editor, change a byte, back to DOS,¢ "DIR", wrong bytes, etc. etc....¢¢ It about drove me nuts! Back to the¢ ol' drawing board? No! I only had to¢ add a few lines that would keep a¢ count of the bad sector and change¢ the free sector bytes before writing¢ the boot sectors and sector map to¢ the disk.¢¢ So, here's beta-test version 1.¢ DiskSaver! by REMlab.¢ It loads from DOS with BASIC enabled.¢ Sorry, SpartaDos 3.2 only in this¢ version and no double density, yet.¢ (But, I'm still working on it. When¢ perfected, it will handle ALL DOSes¢ known to the Atari 8-bit [I hope].)¢ Before I forget, DiskSaver! has taken¢ up a large chunk of my time, and, I'm¢ not yet through with it. But, I still¢ gotta eat! Any donations will be¢ gladly accepted and will be devoted¢ to writing more useful stuff and to¢ the running of my board.¢ If you feel the need, send it to:¢ REMlab % R. Cook, P.O. Box 1144¢ Arlington Hts., IL, 60006-1144¢ Atari! Power without the price! ¢ **END**¢
