Replacing floppy
in [Design]
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From: Archimedes' Lever on 27 Apr 2010 23:20 On Tue, 27 Apr 2010 20:09:44 -0400, Jamie <jamie_ka1lpa_not_valid_after_ka1lpa_(a)charter.net> wrote: >Archimedes' Lever wrote: >> On Tue, 27 Apr 2010 08:27:41 -0400, Jamie >> <jamie_ka1lpa_not_valid_after_ka1lpa_(a)charter.net> wrote: >> >> >> Set your clock right, dingledorf. >Well, that would explain why my virus scanner has been going >off a day early lately.. > > Thanks for the tip, window licker! > You were originally told by the Thompson tard or Terrell tard. You were simply too much of a tard to have caught it.
From: SoothSayer on 27 Apr 2010 23:57 On Wed, 28 Apr 2010 12:32:10 +1000, Grant <omg(a)grrr.id.au> wrote: >'cos floppies are so unreliable, and I have a borrowed instrument that >can dump screen images to floppy. Floppies are fine if you do not rely on the 6x factory format that had no error checking. You MUST re-format, and fully format (not quick, if it is even available) the disk. THEN check it for errors aside from the format's standard check. THEN you can rely on it... a little longer.
From: SoothSayer on 28 Apr 2010 00:36 On Wed, 28 Apr 2010 12:32:10 +1000, Grant <omg(a)grrr.id.au> wrote: >The old Ferguson BigBoard could read floppy drive with Z80 micro running >at 2.5MHz, without a controller. Nasty (tricky?) use of NMI to get the >response time for data transfer though. They Atari 800 had a Tandon 5.25" full height, 360kB floppy drive. The interface was two connectors. If I still had the hundred or so games it had, I could get twenty times what I paid for them now.
From: Grant on 28 Apr 2010 04:19 On Tue, 27 Apr 2010 20:57:43 -0700, SoothSayer <SaySooth(a)TheMonastery.org> wrote: >On Wed, 28 Apr 2010 12:32:10 +1000, Grant <omg(a)grrr.id.au> wrote: > >>'cos floppies are so unreliable, and I have a borrowed instrument that >>can dump screen images to floppy. > > > Floppies are fine if you do not rely on the 6x factory format that had >no error checking. > > You MUST re-format, and fully format (not quick, if it is even >available) the disk. THEN check it for errors aside from the format's >standard check. THEN you can rely on it... a little longer. Yes, but each time I do that I throw out 2 or 3 bad disks, and eventually the floppy drive will go bad too. Grant. -- http://bugs.id.au/
From: Mark Zenier on 27 Apr 2010 11:47
In article <hr4o7b$tts$1(a)news.albasani.net>, Jan Panteltje <pNaonStpealmtje(a)yahoo.com> wrote: >On a sunny day (Sun, 25 Apr 2010 18:27:31 GMT) it happened mzenier(a)eskimo.com >(Mark Zenier) wrote in <hr4f1h073i(a)enews2.newsguy.com>: > >>In article <hr16eu$90e$1(a)news.albasani.net>, >>Jan Panteltje <pNaonStpealmtje(a)yahoo.com> wrote: >>>The serial protocol is either MFM or FM, NRZ code, with CRC added for >>>each sector. >> >>Not NRZ. For both input and output, it's a short (100-300 ns) pulse >>for each flux transition. For the input, inside the drive it's the >>clock for a T flip-flop that (gated by the enables) drives the head. >>For output, it's a one-shot triggered by a peak detector. > >I think you are wrong: RTFDS, I suggest one of the Western Digital floppy controller ones like the 279x family. Or the MC3469, '70, '71 floppy drive electronics ICs. > http://en.wikipedia.org/wiki/Modified_Frequency_Modulation > ><quote> > As is standard when discussing hard drive encoding schemes, > MFM encoding produces a bit stream which is NRZI encoded when written to disk. Er, you see the phrase "when written to the disk". Go look at an old floppy drive schematic. (There's one in the original IBM PC Hardware book, if you're as big a packrat as I am, or I could scan some others that I have). You'll find that the write data line is used to clock a T flip-flop, so what's in the cable is not what's on the disk. > A 1 bit represents a magnetic transition, and a 0 bit no transition. ><end quote> > >I should know, I designed a multi standard floppy controller board, >and it works :-) >It has one of the lowest error rates in the universe, ZERO. >Want the diagram? Check and see if you've got a RC and Xor edge detector on the write data line... Mark Zenier mzenier(a)eskimo.com Googleproofaddress(account:mzenier provider:eskimo domain:com) |