Interfacing floppy drive?
DigitalMan
Posts: 42
It would seem that, of the 34 pins on·a floppy·connector (not too intimidating as it is), 14 are just GND, and only 17 are needed for one fully functioning drive, a couple of which probably wouldn't even be needed normally. 1.44MB is a lot of binary space when dealing with microcontrollers. I would think that using an SX or PIC as an interpereter, similar to how they act in a BASIC Stamp, could result in a massive program, and even multiple programs with more disks. Kind of reminiscient of that one thing... what was it? A computer, that's it. But reinventing the wheel is what I do.
Would there be any special procedures required to hook up an SX chip or any other microcontroller to a floppy drive? It seems simple enough, but motor pulses concern me.
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Chicks dig nerds... but not until after the prom.
Would there be any special procedures required to hook up an SX chip or any other microcontroller to a floppy drive? It seems simple enough, but motor pulses concern me.
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Chicks dig nerds... but not until after the prom.
Comments
I think he has some posts in the forum too.
http://www.techtravels.org/amiga/amigablog/?cat=2&paged=1
Bean.
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Cheap 4-digit LED display with driver IC·www.hc4led.com
Low power SD Data Logger www.sddatalogger.com
"I reject my reality, and substitute yours." NOT Mythbusters
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· I have used a standard 720K (Yes, that was the old standard) floppy drive on·a Z80 System many years ago, and it seems like the SX would be just as adept at it.· Of course, my file system resembled that of a Tape Drive, but it worked.· You just couldn't delete anything or append to anything.· But I was able to save and load data and search the files by filename.
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Chris Savage
Parallax Tech Support
csavage@parallax.com
Unfortunately, they somehow managed to give a chip that accesses a 17-pin drive 40 pins, and it needs two different·clock inputs.·I do believe a certain 28-pin chip could do the job better, I just need to figure out exactly what outputs are needed. I don't intend to use much of·a file system, preferably just a TOC somewhere with addresses of programs.·The data·would then be·passed on to a chip that works much like a BASIC Stamp interpereter.
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Chicks dig nerds... but not until after the prom.
You might want to consider flash media cards.· They are inexpensive, small and can store gigabytes of data.· Many of them use SD media.· They require just a serial data stream (thus you don't have to figure out wiring) and they are compatible with a common desktop PC.
The Saelig uALFAT-SD sells for about $40
http://www.saelig.com/miva/merchant.mvc?Screen=PROD&Product_Code=FF003&Category_Code=FF
Bean sells one for about $70
http://www.sddatalogger.com/
John Couture
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John J. Couture
San Diego Miramar College
The goal of this project set is to learn about older technologies, in order to better understand newer ones. Besides, that amount of memory would be overkill akin to replacing a BASIC Stamp's EEPROM with a hard drive.
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Chicks dig nerds... but not until after the prom.
I think what Chris is pointing out is that the creation of a file and the management of it are not part of the floppy drive. So you will have to either duplicate the MS-DOS format or create one of your own. The convience of MS-DOS is the File Allocation Table and this requires quite a bit of software space. That would be in the BIOS rom, DOS files, and SYS files [noparse][[/noparse]these files would have to be on each floppy].
Before MS-DOS, there were dozens. You might take a look at CPM for publically published information.
Try to figure out how to format and add a system file first.
The old Dr. Dobb's Journal [noparse][[/noparse]of overbyte and orthidontia] presented much of this material. If you can find a library that has kept those, they are a goldmine. The new Dr. Dobb's doesn't provide this material and I suspect it has something to do with that era being very combative about intellectual proprety rights [noparse][[/noparse]so the they bought the magazine's name, not the archives].
IMHO, I think that you can learn as much or more with the SDcards. I have never had a floppy disk not deteriorate in quality. Ferric Oxide seems to do very poorly in Taiwan with the high heat and humidity.
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"If you want more fiber, eat the package.· Not enough?· Eat the manual."········
This would be a tough project! The work involved goes a level deeper than just having to convert sectors into filesystem information.
In IDE hard drives, the "IDE" stands for "integrated drive electronics", meaning the individual magnetic pulses are processed in the hard drive unit itself. You send the hard drive a request to read a sector at some address, and the drive returns a block of bytes. These are interpreted into boot sectors, FAT sectors, directory and data sectors by the computer.
Not so for the floppies. Their interface has a "read" wire which emits a pulse for every magnetic flux transition detected. Thats it. It would be up to you to translate those pulses into bits, bytes, and sectors.
I suppose you could get and use a floppy controller chip, but what fun would that be?
David
When working at this level, with RAM measured in kilobytes, "file" is a foreign term
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Chicks dig nerds... but not until after the prom.