Newsgroups: comp.sys.apple2 Path: news.weeg.uiowa.edu!news.uiowa.edu!hobbes.physics.uiowa.edu!math.ohio-state.edu!howland.reston.ans.net!spool.mu.edu!olivea!apple.com!goofy.apple.com!mumbo.apple.com!gallant.apple.com!kip-112.apple.com!murph From: Jim Murphy Subject: Re: MORE on flopticals and their ilk Sender: news@gallant.apple.com Message-ID: <1993Jul29.215913.13227@gallant.apple.com> X-Useragent: Nuntius v1.1.1d24 Date: Thu, 29 Jul 1993 21:59:13 GMT X-Xxdate: Thu, 29 Jul 93 14:59:33 GMT X-Xxmessage-Id: References: Organization: Apple Computer, Inc. Lines: 29 In article <1993Jul29.182950.23002@wixer.bga.com> Dave Huang, khym@wixer.bga.com writes: >BTW, can someone from Apple tell me how the MSDOS FST checks to see if >a disk is in MSDOS format (if it's not too complicated :-)? MSDOS >disks that I make with "mformat" aren't recognized by the FST, but >real MSDOS disks formatted on an IBM work great. Is it the lack of a >real boot block? Well, looking at the source, the FST takes 5 steps to determine if a disk is in MS-DOS format. All of the steps must be successful. They are: 1 - Read in block 0 (the boot sector) 2 - Byte at offset $000 must be $E9 or $EB (8088 short jump or long jump instruction) 3 - Byte at offset $1FE must be $55 (ID byte) 4 - Byte at offset $1FF must be $AA (ID byte) 5 - Bytes at offset $00B-C must be $200 (Bytes per sector must equal 512) That's about it. Jim Murphy murph@apple.com "...never quite said what I wanted to say to you, The Cure never quite managed the words to explain to you..." Untitled