FD-55F Series
Technical Specifications
The TEAC FD-55F never appears in the world of IBM compatible computers. Why is that? Because it is simply superfluous in the DOS world.
The TEAC FD-55F is a double-sided 5.25 inch drive that can write 96 tracks per inch (TPI) with 9 sectors per track. In other words, the capacity of a floppy disk is 720 KByte. This corresponds to the capacity of the standard 3.5-inch double-density (DD) drive. This 3.5-inch format has been supported since DOS version 3.2.
This was probably one reason why the 5.25 drives with 720 KByte did not find their way into the IBM world.
The MS-DOS Enzyclopedia, 1988, p. 865
FORMAT [drive] /4 - formats a standard double sided, double density disk (360 KB) on a quad-density disk drive.
Note: Each OEM determines which switches will be supported by the FORMAT utility included with the versions of MS-DOS sold with its computers.
I don't know any floppy disk controller or standard BIOS that supports this 5.25 inch QD disk drives on IBM compatible computers. Also the CompatiCard only supports a pseudo format with 800 KByte but not 720 KByte.
In the CP/M world the TEAC FD-55F can be found very often. There are a lot of disk formats with 80 tracks or 96 TPI. You can easily test this with the DOS program 22DISK. Simply select the appropriate format and format the diskette (initialize). This works without any problems. You even get a hint from 22DISK that 96 TPI (5.25 inch) are only supported by 1.2 MByte drives or by the TEAC FD-55F!
Jumper Settings
You have to be a little careful with the jumper settings. I have for example the type FD-55F-30. This has no DISK CHANGE (DC), but only the READY (RY) jumper. In other words, this drive does not work on an AT (I also tested it), but on a PC/XT, see also under Jumper settings. Another special feature is the XT jumper, which I don't use, I only use RY.
My jumper settings are: DS1 / IU / RY / FG
On the picture above you can also see the so called terminator or resistor pack. It is not set because I am using the TEAC FD-55F as drive B:. Only the last drive on the cable must have a terminating resistor installed! Attention! The TEAC FD-55F requires a 14 PIN resistor with 330 Ohm!
A Test With 22Disk and Uniform
I use the TEAC FD-55F with my IBM PC or XT and it works fine in combination with the programs 22Disk und Unifom PC. In other words, I use the floppy drive only in conjunction with external CP/M formats. Example:
22Disk:
- c:> cfmt /kay4 b:
- c:> dtoc /kay4 test.txt b:
The first command formats a diskette in drive B: in CP/M format DS, DD, 96 tpi (kay4) for the Kaypro Pro-8 Rom. The second command copies the file test.txt to drive B:.
With Uniform I selected the CP/M format "Kaypro Pro-8 Rom DSDD:96:CPM". Under PC-DOS the access is quite simply possible with DIR B:. The file test.txt is displayed correctly.
Changing a FD-55GFR to a FD-55F
... or, how do I get my drive to spin at 300 RPM instead of 360?
You need a 720 KByte floppy drive for your CP/M Kaypro but you only have a FD-55GFR (1.2 MByte)! Nothing easier than that. Just reduce the rotation speed from 360 RPM to 300 RPM and you have a 720 KByte drive with 80 tracks and 96 TPI (double sided, quad density, DSQD).
This modification can be done quite easily with the following four TEAC drives.
- TEAC FD-55GFR-149-U
- TEAC FD-55GFR-193-U
- TEAC FD-55GFR-570-U
- TEAC FD-55GFR-7193-U
I have tested this with my versions -149 and -193. It works flawlessly. There are many other subtypes of the FD-55GFR. I therefore assume that the situation will be similar for the others. Just give it a try.
Decisive here are the three jumpers I, IS and LG, see TEAC FD-55 jumper settings below. Furthermore, you need to tape contacts 1, 2, 3 and 4, that's it. You can also find out more details here.
Hearing test: Use a jumper with a long grip for your test at "I". Make the drive rotate and remove the jumper. If you have good hearing, then you can "hear" how the rotation speed changes.
Specifications (S) and Brochures (B)
- S: TEAC FD-55FV
- S: TEAC FD-55 Jumper Settings
- B: TEAC FD-55 Series (A, B, E, F, G, GF)