For all of you who just adore (and only adore) Windows XP, start laughing at me, because I am going old school style.

What I want to do is be able to actually read any byte I want from a floppy disk. I am using a standard 3 1/2 inch floppy disk drive to help me out.

The problem is that everything I have done so far has lead to failure.

I even tried connecting the output pins to the LED's and the only output pin that seems to work is the write-protect detection pin.

When I plug the floppy drive into the computer, it works normally.

I have searched several websites, and there is not one single website explaining the details on how to manually read a single byte from a floppy disk!

Why do I want to do this? Because it is SAFER, and the risks are somewhat lower.

I want to eventually take raw data from a floppy disk, (from bit 0 to the end) and program a microcontroller from it.

Also, I want to program some bios chips and hopefully get my old bios working again.

I just picked up another motherboard, and I am using it now as part of my computer. The only two drawbacks are loss of speed, and no CD-ROM booting.

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-=: The best low-priced components to troubleshoot with are the speaker and the LED :=-

 

What do you mean by manually read a single byte?

Are you looking for software to do that for you, trying to write software on the PC that'll do that, using a uC connected to the drive? Your post is not clear on what you are trying to achieve..

 

It's not 'old school' it's more 'pre-school' :lol:

As you don't have the faintest idea how disk drives work, why do you find this suprising?.

You need a 'floppy disk controller', these used to be available (30+ years ago?) as a chip set, to connect between the drive and your micro-processor. For many years now they have been part of the large chipsets on PC motherboards.

BTW, a poster on my wall (of my first computer system), shows a picture of the floppy disk controller (which I never had, too expensive!), it has 23 IC's on the board!.

That's because it's not possible! - you can't read a single byte from a floppy drive (or a hard drive or CD-ROM either). The minimum amount you can read is a sector, which varies depending on the size of the drive, large drives have large sector sizes!.

If you do a web search you can find IDE interface details for connecting CD-ROM's to PIC's (and other micro-controllers), but an IDE interface has most of the controller circuitry on the drive, so the external interface components are minimal.

There was a long thread on the PICList years ago about trying to use a floppy with a PIC, as far as I know no one managed it? - an obvious snag is the lack of RAM, as you need to store at least a single sector.

__________________
PIC programmer software, and PIC Tutorials at:
http://www.winpicprog.co.uk

 

IF you were in linux I would suggest "dd" and make a copy of the floppy (byte-wise) and then edit that

OR just go "vim /dev/fd0"

however, since you seem to be a windows user, I suggest
http://www.hexworkshop.com/

I used this back in 95days when I had to learn abt harddrives and the VFAT filesystem. I started with floppies and then carried on from that.

__________________
Nothing is impossible.
Once a problem is realised, the rest is just details

 

As Nigel stated, you cannot read/write just a byte. But only in sectors (for a floppy with VFAT that is 512 bytes)

However, with a sector loaded you can then manipulate the byte you want and write that sector back

__________________
Nothing is impossible.
Once a problem is realised, the rest is just details

 

However, reading your post a bit more..

You want to interface directly with the floppy. IT is possible, just goto a floppy drive manufacturer and they should have the pin-outs as well as access times

__________________
Nothing is impossible.
Once a problem is realised, the rest is just details

 

Your motivations are somewhat weird. Why is a floppy disk reader safer? Anyway, I've interfaced MMC cards before. I believe CF interface has also been achieved before, but obtaining a CF socket may be somewhat tricky. I've even implemented the FAT on the MMC. Works fine and "safe". These cards pack many times the size capacity of the humble floppy, are fungus resistant, compact-sized, non-mechanical ...
Next, isnt it much simpler to make a less fancy serial/parallel programmer?

 

Yes, reading compactflash or Secure digital cards with a pic (or any µC) is easy...

Compactflash is the most easy and doesnt require extra memory (like Nigel said , you need to read 1 sector at a time wich is 512 bytes for CF, but the CF card has a 512byte buffer built in) - it does however require a whole lot of µC pins.

SD is a little harder and you need your own 512byte buffer memory (I²C ram would do nicely, or a µC with enough ram to spare), but since it's serial it only requires few pins...

And face it, a memory card slot on your project is a lot better looking then ickky disk drive :lol:

There's lots of info on the net 'bout CF & SD interfacing.
I would also like to add that a memory card is safer then a diskdrive...
I haven't had any data failures on a memory card yet, but my pile of defective diskettes is getting larger all the time...

 

After making a programmer with using a parallel port, I have in the process damaged one parallel port on my old motherboard (which is now trashed). Using removable storage and transferring it to my programmer is IMO a safer approach because then I don't risk damaging another port.

The only other options I have is to interface my own programmer with a CD-ROM drive, or a hard drive. I prefer using the floppy drive because there are only 34 pins to deal with, and from what I have learned, 1/2 of them are grounded.

__________________
-=: The best low-priced components to troubleshoot with are the speaker and the LED :=-

 

You want to design an interface so that you can connect your microcontrollers to a floppy drive for the purposes of programming them???

I really can't understand why anyone would dream of doing such a thing. You're going to need to design your own file system, and write some firmware to support it. Once you've done that you're going to need to write some software which will take the data you've obtained from your floppy drive and program your required microcontroller with it using the required protocol for that particular microcontroller. If you then decide you want to program a different type of microcontroller, you're going to need to re-write part of your software to support it and you're going to need to do this EVERY time you decide that you want to work with something different. Then you're going to need to build a dedicated system which permanently interfaces to the floppy drive, and a suitable output interface for connecting to the desired microcontroller. This interface would also have to be adapted each time you chose a different type of microcontroller to work with.

Even assuming you're willing to do all that work, and you're capable of doing it, I still don't see how you're the slightest bit better off. Especially since floppy disks are a highly unreliable way to store information. If you've been damaging parallel ports using parallel programmers, you've been doing something wrong.

Hmmm

Brian

 

If you've damaged the parallel port it's because you've done something stupid! - from your previous posts when you did it, you did everything ABSOLUTELY STUPIDLY!

Just use a little common sense, respect what a parallel port is, and don't attempt your usual random connections!.

In the same vein, your floppy programmer idea is even more stupid!, there are numerous programmer designs out there, pick one and build it properly!.

__________________
PIC programmer software, and PIC Tutorials at:
http://www.winpicprog.co.uk

 

Maybe nigel can cool off abit.

We've all done stupid things at various points of our lives.

 

Try reading his previous posts when he killed his port! :lol:

__________________
PIC programmer software, and PIC Tutorials at:
http://www.winpicprog.co.uk

 

Yes

Lower Risk taking, Code Portability, Selective programming, etc. :wink:

That is easy. I will use DOS interrupts or access the disk by port address and write byte-by-byte.

In this case, I doubt I will need software, because if I just program raw data, sequentially, I think I can get away with a shift register, and a counter. The counter can then terminate disk reading when a set amount of bytes have been read.

I'm only using one kind of microcontroller now, so this won't apply to me.

This is the part I need help figuring out. That's why I wanted to know how to read a bit from the disk.

I would find it more insane, bulky, and time consuming to create a CD just for 2K of information.

The programmers I dealt with were all made by myself. Incidentally, one programmer worked nicely, but lacked some functions.

__________________
-=: The best low-priced components to troubleshoot with are the speaker and the LED :=-

 

Anyway, the main issue is that you have weird notions of "better" that the majority of us feels quite unacceptable, or just a waste of time.