On Wed, 23 May 2012 09:22:03 Jack <...@earthlink.net> wrote : > Subject: Re: [Freedos-user] Virtual floppy change problem
> You are WRONG, Tom!! Is he ? or are you being RUDE, Jack ? > UIDE has NEVER ignored if a diskette has change-line support! It > does in fact check the BIOS data table at 0:448h for bit 0 (change > line for diskette A:) or bit 4 (change line for diskette B:). If > those bits are off, diskette A: or diskette B: will not be > cached. Not Tom, but I'd like to learn from /what exact source/ you got the definition for those bits. They are not universal, and we need look no further for why UIDE floppy caching may fail. Does that reference state that it applies to IBM-PC, PC-XT, PC-AT, PS2... or maybe some BIOSes of some particular brand and/or period ? In any case BIOS data byte [40:48] is /not/ documented in Ralf Brown's files, nor is it in Michael Tischer's book (other than HD/FD related). I have the source listing for a Goupil G5 BIOS ca. 1990 (a very faithful, and one of the rare "authorised by IBM", PC-AT clones) - those bits aren't used for disk change lines. An authentic IBM AT BIOS is accessible on the net, I haven't found the need for fetching it, someone might check there also. /Possibly/ those bits were defined as floppy line flags in the PS2 'compatibility' RM BIOS , I have no idea - having checked a PS2 technical manual which unfortunately doesn't have the BDA details. Now, puhlease! don't feel accused - I'm sure you did not make those bits up and that they work in your test machines and even for the bulk of your users . That you wait for users' complaints before checking the soundness of your assumptions is another question entirely. You are entitled to choose any method that works on recent gear if you find it convenient. But rather than pretending to support floppies on the whole range of DOS-capable PCs, and claiming that those that do not conform to your model are junk (or is it the users' fault ?) - you /must/ find a way to programmatically assert that your far from universal method /will/ work and take measures otherwise. IMHO you can't leave it to the (clueless, always...) user to assert his or her PC is not conforming to UIDE's model. Regards -- Czerno ------------------------------------------------------------------------------ Live Security Virtual Conference Exclusive live event will cover all the ways today's security and threat landscape has changed and how IT managers can respond. Discussions will include endpoint security, mobile security and the latest in malware threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ _______________________________________________ Freedos-user mailing list Freedos-user@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/freedos-user
