Some times it reads part of the disk. I don't know what it is looking at but it won't format over some types of original data. I've often erased with supper magnet to get past such stuff. It may also be that is just doesn't support 77 and can only do 80 tracks. Dwight ________________________________ From: cctalk <cctalk-bounces at classiccmp.org> on behalf of Terry Stewart via cctalk <cctalk at classiccmp.org> Sent: Monday, April 17, 2017 4:36:01 PM To: General Discussion: On-Topic and Off-Topic Posts Subject: Re: Extracting files off ?unknown? 8 inch disks. Any thoughts? adventures-with-an-8-inch-disk-drive-part1.htm One thing in this project puzzled me. Initially when I was testing the drive I tried to format it for 77-tracks. I used the command FORMAT B: /u /T:77 /N:15 . It wouldn't let me. MS-DOS said " "Formatting 1.15M parameters not supported by the drive" After trying a few other things (unsuccessfully) I just tried a straight FORMAT B: /u It then formatted it without complaint? Listening to the head moving, I counted 77 tracks. The last three tracks the clicking stopped. I'm assuming the head just wrote over that final track 3 times. MS-DOS told me I'd formatted for 1.2MB. I'm puzzled why I couldn't format the disk using the /t:77 and /n:15 switches. Did MS-DOS just go by what was in the CMOS. If that's the case, why have those switches at all? Are they just legacy switches for pre-CMOS machines? Anyone know the answer to this? Terry (Tez)

On Tue, 18 Apr 2017, Terry Stewart via cctalk wrote: The /T: and /N: switches do NOT set the number of tracks and sectors! They just don't! Instead, their function is to gather answers to those questions from the user, that the OS then uses to select which one of its limited number of formats matches what the user is requesting. It's like retail sales systems that ask my city, ask my ZIPCODE, and then change my city in my address from Berkeley to Albany for zipcode 94706 and (Yes, there are MANY ZIPCODES that straddle city boundaries, MANY that straddle county boundaries (a problem in correct computation of sales tax (cf. XenoSoft Sales Tax Genie)), and even a few that straddle state boundaries.) For example, /N: has values of 8, 9, 15 /12 won't be accepted. /T: has values of 40 and 80. If you are using a Shugart SA400, it should have also accepted 35. If you are using an 8" drive, it should also have accepted 77. For that matter, it should accept anything less than or equal to the limits of the drive, and use what you ask for, so that you could format 35 tracks, or 77, or 70, or 53, if you want, instead of only using your request as a selection between it's option. It has a very finite list of supported formats, and uses your variable settings only to select which one of THOSE to use! At one time, MS-DOS had some other drive types! DRIVPARM (and the related DRIVER.SYS device driver) were first visible in DOS 3.20 (the first time that all DOS supported 720K, although many OEM versions of 2.11 were configured with manufacturer specific additional drive types, such as Gavilan 720K MS-DOS 2.11K) DRIVER.SYS created a new drive letter (at the end of your drive letter list) accessing the drive, whereas DRIVPARM did an override of the drive type that was set in CMOS. If your BIOS CMOS settings didn't include 720K, you could set the CMOS to 360K, and use DRIVPARM/DRIVER.SYS to switch it to 720K. With DRIVPARM, it could still be B:, but with DRIVER.SYS, it would have a letter after your hard disk, etc. (Did you set LASTDRIVE?) At that time, type 7 (1.4M) and type 9 (2.8M) didn't exist yet, and it would also balk at drive types that were contrary to what DOS believed that the BIOS/hardware could support. (Neither the hardware nor INT13h needed any change to switch from a 160K/180K/320K/360K drive to a 720K) But, with DOS Version 6.00, type 3 (single-density 8-inch floppy disk drives) and type 4 (double-density 8-inch floppy disk drives) are no longer supported. With your CMOS set to drive type 1 (1.2M), what happens if you try to use DRIVPARM/DRIVER.SYS in DOS 5.00 to switch to type 4? Or /F:4 in DRIVER.SYS? NOTE: Many sources, INCLUDING MICROSOFT "support", have erroneous information about which versions of MS-DOS and PC-DOS support DRIVPARM. It's understandable, with MY experience I could easily misinterpret it in numerous incorrect assumptions. On a generic 5170, using 720K drive WITH PC-DOS and MS-DOS 3.20, DRIVPARM worked fine. But, when I replaced its BIOS with a copy of the "real" IBM BIOS, both operating systems reported "UNRECOGNIZED CONFIG.SYS COMMAND" for DRIVPARM! So, I had to use DRIVER.SYS. Replicated on an OEM 5170. Other weirdities surface: Chuck reported needing to tamper with the CONFIG.SYS line to use it. (perhaps he could repeat his explanation?) and http://www.uncreativelabs.net/textfiles/dos/BDRIVE.TXT -- Grumpy Ol' Fred cisin at xenosoft.com