MFM Floppy drive?

[bbcmicro]

Yes, I know this is in the luggables forum, but my question is as follows;
I have a Sharp 7200 luggable, as far as I know it's IBM compatible. Boots from a 5.25" floppy as it has either a dead HDD or has forgotten it through a flat internal battery. No idea which format floppy but I do know it's single sided. Lost the one boot disk I had so is now a doorstop (This is why I need a 5.25" drive for my PC! Unfortunately, temporary removal from the sharp to a PC, it didnt work with any of the 2 availiable options in my PC's BIOS (360 or 1.2) So if it is to boot again I will need a PC that supports this unknown format or someone to make some disks for me)

Upon inspection inside it had what I can only guess is an MFM drive. Its big and square, with no inlet for power, with a green and grey ribbon cable which is narrower than a standard IDE. I have never seen an MFM drive and had a guy point at it and state that it is, so I may be wrong.

I have a floppy drive pulled from a T3100e which also looks MFM. I have never heard of an MFM floppy, but I haven't really been listening. It has the same cable and plugs, again no input for power.

My question is thus, If I could access the BIOS and set it up, could this 1.44mb floppy be used in place of the MFM drive, or would it be like plugging a IDE FDD into an IDE HDD slot (If that was physically possible) and with possibly disastrous results? This isn't really practical and the question is out of curiosity. If I wanted an extra drive I would use a normal one with a split cable & card edge connector, but I would still need a disk for the BIOS.

[dreddnott]

MFM (modified frequency modulation) simply refers to the type of encoding used to write the data to the disk surface. In fact, nearly all floppy disk drives (including your fancy new 1.44MB floppy) use MFM encoding.

What most people think of when they think of "MFM drives" are actually the ESDI/ST-506 connectors that connect MFM and RLL hard disk drives to the controller card.

I've heard of several types of floppy drives that don't have a separate power connector (early Macintosh, IBM RS/6000) but since I'm not at all familiar with the Sharp 7200 luggable, I'd like to know more about your system - post a pic or count the number of pins (it's not an edge connector type, is it?).

I'm also pretty sure that if you plugged it in direct, you would likely fry your floppy drive and possibly fry the motherboard, because the 5 and 12-volt DC is being delivered through that ribbon cable, rather than a separate power adapter. Blam!

[bbcmicro]

At the moment its in pieces, takes 15 minuites to put back together so I'll post pics in a mo.
I'm glad I asked before I tried it!
Thanks.

[bbcmicro]

http://img149.imageshack.us/img149/2772/joe003vc4.jpg
http://img145.imageshack.us/img145/6812/joe002wb1.jpg
http://img88.imageshack.us/img88/4176/joe001hu6.jpg

Waiting for floppy images to load...

[bbcmicro]

http://img174.imageshack.us/img174/1161/flop001gg8.jpg
http://img137.imageshack.us/img137/7863/flop002oz6.jpg
http://img174.imageshack.us/img174/3364/flop003ai1.jpg
http://img83.imageshack.us/img83/9828/flop004ht4.jpg

A sticker on the back of the luggable tells me it is a Sharp 7221.

[nige the hippy]

Is that floppy drive going spare? they're a bit hard to come by.

If the hard disk is an old "mfm" one it will have a wide (40 or 50 way I can't remember) connector for control, and a 20 way (or so) one for data as well. It will also have a power connector.

so something big & square with a narrow cable???? god knows wirhout looking at it... more pictures!

any floppy drive I've heard of uses MFM encoding same as early hard disks, BUT the interfaces are totally different.

Like with the serial interface FORGET PLUG & PLAY EVER EXISTED! in the world we're dealing with here, the only intelligent peripheral is the human.

my batch of 5.25 floppies should be here soon etc....

[bbcmicro]

If that's the case, then the Sharp drive may not be MFM. It just has a 26 way connector, as does the floppy. I have no idea what standard these are!

Yes, the 3.5" floppy is up for grabs if you still want it!

http://img133.imageshack.us/img133/9522/hdd001gc6.jpg
http://img147.imageshack.us/img147/9222/hdd002fe0.jpg
http://img167.imageshack.us/img167/9571/hdd003ma9.jpg

[nige the hippy]

just did a bit of googling and an old thread from this forum popped up

http://www.vintage-computer.com/vcforum/archive/index.php/t-171.html

may be slightly useful.

It did remind me about it being worth clearing the CMOS on PCs that just won't boot. the info on the screen often makes sense, but the actual drive configuration in memory is corrupt.

on old pcs, either disconnect the battery, or if there's a jumper do whatever with it, and wait 10 mins.

[bbcmicro]

I don't think its the CMOS battery, I already tried that a while ago to see if the default settings would get the drive to boot.

Unfortunately I cant make a setup disk or a boot disk, no 5.25" floppy drive (Arg, I feel like I'm going in circles! it all comes back to a floppy drive) I dug out another disk, and it boots to DOS 3.x alright, but it is full of crap, its a bit flaky and tries to make a ramdrive, with no EMS thats pretty useless. I cant copy it because I have no ramdrive or HDD. I would be happy with another 5.25 instead of the mystery disk but thedrives are a wierd size. Not quite half height but a bit bigger than a quarter, if a quarter is half a half height(?)

[nige the hippy]

ok I'll get a pc compatible 5.25 drive to you as soon as i have one. Do you also want the rs232 breakout box?

[bbcmicro]

Please :D
(Feels blood pressure ebb away...)

[nige the hippy]

your luck's in boyo!

floppies arrived today, can't believe it, they're half height DS/DD 40 track drives BRAND NEW!!!! (still sealed in bags & boxes) and appear to be rather nice cast chassis tandon/sankyo TM65-2L

I've another parcel to post tomorrow/thursday, you hopefully should get them friday.

of the rest, what I don't need will be going on ebay shortly. unless there are any requests.

nig.

[kb2syd]

Well, I'm always looking for DS/DD drives, but shipping to the states would put these out of my price range.

[nige the hippy]

you could probably buy them in the US for less than the shipping

[dongfeng]

edit: misunderstood the question...

[kb2syd]

you could probably buy them in the US for less than the shipping

That's what I meant...

[bbcmicro]

Hurrah! :D

Nig, do you want that strange FDD? Still not sure what it is!

[bbcmicro]

I found the harddrive was just inside a metal cage...

Inside there was a black JVC drive with blue rubber corners, "Hard Drive Disk Model JD3824R00-1", serial 12246958, once such example here:
http://cgi.ebay.com/JVC-20mb-Hard-Disk-Drive-Model-JD3824R00-1_W0QQitemZ8817454164QQcmdZViewItem

Google yielded a few references but not to what interface this is.

[Mike Chambers]

i wouldn't be surprised if that drive is compatible connector-wise with the ones in my osborne. sounds like what you're describing, and the power is fed through the ribbon cable. i couldn't tell you the name of the standard though, sorry.