From c81f5d6fe45e2953b5a560f1104a5213fb0c37be Mon Sep 17 00:00:00 2001 From: David Given Date: Thu, 7 Mar 2019 23:20:54 +0100 Subject: [PATCH] Talk about flippy disks. --- doc/525-floppy.webp | Bin 0 -> 7630 bytes doc/faq.md | 55 +++++++++++++++++++++++++++++++++++++++----- 2 files changed, 49 insertions(+), 6 deletions(-) create mode 100644 doc/525-floppy.webp diff --git a/doc/525-floppy.webp b/doc/525-floppy.webp new file mode 100644 index 0000000000000000000000000000000000000000..cb08fbf51c592f743033b69aeee3cc563f55f9e8 GIT binary patch literal 7630 zcmV;<9WmlkNk&G-9RL7VMM6+kP&il$0000G0000h0RSuk06|PpNZJJe009ZcZ6qmD z_ww%KAMr9BydwHP0oW)3s!90&;l0Q_G6Q$R*FxpIuM$O+p4woG0Z13i@cbbm&T0hl9>4e=nt4lULU|q;w3JLm&O?AX1%v6*f8^E z5ff^flpZK$!DM0%5M75`!2`*c@YN{2nZMY%ier-ReSd9 ztDy0c+b$`4+--qlo?4e(J9*IgQ5Bcb1EjK*BN9f{$TB%%Q^qg^5@n4Zl&bP1QB69+ z#I#B{MRE!(A*-ay9H~S#9RbyaB~)ce4U~r=vS$??0ij%uI3Ov-stl{pDN3h+R%w(X zEUM9*Vo9ltVF+Xy0TW zRh3SWoZ?l6AtaT-kz^SSL3lWvLKsp~m1GDA)ubWhl`NACfjUbH^)y68oeTk%k%kz@ zs*(($go7iTLaVfiP#{3fbc$D_IfZ<%3cT{5Ra(WXtvN+ zr$DL-M@T3OM`Ri42$fkHHTA`c*TE(gl3rDC7q=!RFP)I@%yecUI z)F7ddfSU4(ph$ok^a`N}P9>dURyl=yuu3>WDwC`Nrvwdgz>$tnnJ4Rlh9IRPOG+rG zBTz0GVw5pxh%5tPRa(W7gsSKWp`0|t0STwdDi2;22&D;738#jf0uc&fRJJqTUR8ikZm%$lSV0Y(7`r)*9E;nb82$ahZ2PB=6a*FU!V95{>Re~c~hLj;pEJu)KnTAl7SuzhmLr7(k zA;7YUI*$ks--Hn2?YdO*X|9@YSeOxq3-5pZxJx9zi>#1+s+Tu5(}e)IV_D+dgnR1uYRG0C9l; z2%Urn(iQ>nM8dh>-B^b!p7V^$FKfF<3iBo0S{-pxW=Bw9YKKx|BY+xXZqn*#t04o( z9RdMf5WNI(i86&oLCTy0$l%sI5fCLl=O|K;}XOK>#8kafwp{m-L_00OGoDjK8!0Is%x1i>38xRU^gM>`ExP&gpQ7XSdzgaDlZDl7pl z0X{JjheDzuA|bCnXwX0g32AMD-j#0PKN*3pdt@7^*?LoE{7PzT;J@2%i}d}tqn^V~ zfzT1zlAG7KK^-r{2Gnv8pKkdJ|9&{a4{-J-7e>ndg-z(xjwE2X42lU_f-`;;C ze5E}~@c{m1{b&7;Dkjr@0KcC9Y5%qAZT~0wf6JeKzfk|{_YnSn{mcH4)1Q1&!4+{& z$hHra&u?Ey6^v|R+`Q`Uo{9jdOgJ3gJk)M%OhRbw(h45B1Wz10n7+-y)@|-~*D?jz z_HwN=FALZGsewyMD}nTFLW(MdN{6cfaCG?4U2!BWI>4^Lzp2~w6g6xd&TZL^R1#F z>_Yii82A&oX1pv=d1CkK5{KJw4!upMl1@k5OVr&o;a@4u?Xar?^xi|h`Kie|77;q@ zrN^jeefOk7$_$wl79SkzumB?&r?6GeY+;vvjT-`@vp?1s(6-)^%Zv<*F!Tj#aay6a z0%rsdX>DKn$&f?+fw7{}eXtwNQ~Ex8hY-WH9^3b1l7^fpvS{3$cnqKXhQfT=8X%H| z2>OE%Dc-5c>f1@R_IK8>7X=Zmt`d*4-e*MNMukbQY9k0kT_nc79Ztnwr`5+@^=0#j zUZPa*UeuB~OAP{3DqnUfm0*wM|9+H@$#%K(lU>9k>zGagE%#9dxZc+Q*8{hV&}hdV zd`MZ$7eR^)==1&4i{X?${}RncXO6Vj$)O|(EpG#NEpxVFwQ(%Co%5-0R?SGJ2)W9u zb5Gnba1SWW9ZNAEDwCCYB8~SUuLSDT+*0O!9B^666`jVL(f|BT;K60t-c&dNmla6r zy*e?agopfwy7LvyBckWWxnT!2)kCk!A@hZa@)ltz%;nb#MP(9k=hiZ70~C=2OE8s` zisbuG85gi-adhK}b%m8G$4uOd#*Z|K+b$ZS>SKLUWhy72ibSJR*SL`NP0SPAq8W(! 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If anyone wants to give it a try, please [tell me about it](https://github.com/davidgiven/fluxengine/issues/new). -**Q.** Is this like KryoFlux / Catweasel / DiskFerret? Do you support KryoFlux stream files? +**Q.** Does it work on hard sectored disks? + +**A.** Probably? I already have decoder support for some hard-sectored disk +formats, based on Kryoflux streams people sent me, and the firmware supports +reporting index hole information, so in theory it _should_ work; but I +haven't had the chance to try it end-for-end. I really need a hard-sectored +5.25" floppy to test with. + +**Q.** Does it work with flippy disks? + +Uhhh... probably not. + +So the problem with flippy disks (5.25" single-sided disks which could be +inserted upside down to read the second side) is the index hole. Trouble is, +the window to let the sensor see the index hole isn't symmetrical on a 5.25" +disk, so if you turn the disk upside down, the drive can't see the hole any +more: + +
+non-flippy 5.25 inch disk +
+ +Some flippy disks had two windows, so they'd work properly either way up, but +most didn't. This was fine on a lot of old machines because those drives +didn't have an index hole sensor. But a lot of modern drives use the index +hole to detect whether the disk is actually present and if they don't see it, +they simply won't work. There's nothing FluxEngine can do; it's a hardware +limitation. + +(If you have one of the rare disks with two index holes, then FluxEngine +_will_ read those.) + +There are workarounds. One is to read the data on the other side of the disk +using the other head --- because, of course, modern drives are double-sided. +Sure, the disk is spinning in the wrong direction, but that's no problem. +Except there _is_ a problem, which is the tracks on the two sides of the disk +are not in the same place; one side has them offset eight tracks compared to +the other. But a flippy disk has both sets of tracks in the same place, +because they're both accessed using the side 0 head... + +The only real way round this is to modify a 5.25" drive. That's _seriously_ +not in FluxEngine's remit. Sorry. + +**Q.** Is this like KryoFlux / Catweasel / DiskFerret? Do you support KryoFlux +stream files? **A.** It's very like all of these; the idea's old, and lots of people have -*tried it (you can get away with any sufficiently fast microcontroller and -*enough RAM). FluxEngine can -read from KryoFlux stream files natively, and there's a tool which will let -you convert at least one kind of Catweasel file to FluxEngine's native flux -file format. +tried it (you can get away with any sufficiently fast microcontroller and +enough RAM). FluxEngine can read from KryoFlux stream files natively, and +there's a tool which will let you convert at least one kind of Catweasel file +to FluxEngine's native flux file format. **Q.** Can I use this to make exact copies of disks?