5.25" floppy disks

8 inch floppy disks were first popular floppy disks. They were used in nearly all aspects of computing in 1970s and early 80s.

These floppy disks were used in computers, workstations, microcomputers, industrial analysers and machine driving computers, and even in some terminals.


Manufacturer: different

Type: Disks
Capacity:  80kB-500kB, some had 980-1200kB.

Fortunately, most PCs will work with many 5.25" drives, they only must be jumper-configured do DS1, not DS0. It's needed in BIOS to set it as 1.2MB or 360K. Very old drives, such as these from CP/M machines (Quad-density) usually won't work well. Disks from microcomputers (Commodore, Atari) may be modulated in GCR, not MFM, so they won't be readable/writable easily in PC 5.25" drive. You can use special cables to connect Commodore drive to PC or use some programs to only read these disks, they may work.

Many times you don't have a sleeve to put your disk into. You should keep 5.25" disks in sleeves when not in use, as they have no cover to protect media from dust. Get this PDF, print it out and glue tabs to make a sleeve.

If you try to recover old 5.25" disks, especially from high-humidity environment, remember about floppy "hardware virus" - read FAQ for more info.

And don't forget to look at:
 - Cyberden's 5.25" Floppy disk sleeves archive
 - A nice explaination of PC floppy interface in John Eliott's Floppy drives Page

If you try to use higher density floppies in lower density drives (like PC disks in Amiga), you may have problem: Data written in higher density drive will be usually readable, but erasing them and writing data may cause errors.
Why? Higher density drive has stronger head, writing bits stronger. Weaker head can't remagnetize higher magnetized surface.
There's only one solution: Use HD-written disks only to put data TO low-density drive system, but write on this system to completely magnetically blank disks (after formatting in low-density drive), these disks should be never written with a higher density disk drive.
Making these blank disks is easy: Just demagnetize the disk entirely. To do it, you can use AC electromagnetic coil or even transformer soldering iron. Standing 2-3m away of media power electromagnet or soldering iron on. Slowly move it near the disk, make few swinging/round moves few centimeters near media. Repeat it for about 30 seconds, may be longer, but DON'T TURN IT OFF. Before turning off move coil/iron 2-3m away from media, or it'll stay magnetized some way.

Downloads for floppy disk? Yes.
"Thanks" to TEAC who deleted their all floppy knowledge base, ha, ha
 - Backup copy :) Not 100% complete, but it is.
 - FD505-XXX Manual (PDF)
 - FD55BR-XXX Manual (PDF)
 - FD55GFR-XXXX Manual (PDF)
 - FD235HF Manual (PDF)
And of course compilation of various FDD jumper settings in PDF.

3.5" drives manuals are in 3.5" disks page.

Here you'll see a few examples of 5.25" disks, drives and accessories. You can also look in PCs or 8-bit Micros, as they may have their own floppy disk drives. In these examples you can see what mechanisms are used in floppy drives to move head or disc itself.

Let's describe typical mechanisms of 5.25" drive: Head (or two on carrier in more popular two-sided drives) is moved horizontally by stepper motor. The same time, disc itself is spinned by hub motor. To carry motion from motor to disc, a locking mechanism with something like a clutch is used, locking the disc in the shaft of engine. This mechanism is usually equipped with lever, flap or button to put the upper part into the hub locking the disc. If it's misaligned or worn out, disk is kept in lock when lever is unlocked, usually spinning hub makes it unlock.
To get information about mechanism, a series of mechanical or optical sensors are used. Typical are:
 - Optical barrier looking for write protection and disk change, as if you change disc you have to break optical barrier for write protection.
 - Index hole - in many drives, to monitor for start of tracks, optical barrier located near the center of the disc. In fact only hard-sectored disc use it in its typical way.
 - Lock monitor - usually mechanical switch used to tell the drive that it's closed.
 - Optical barriers to keep head moving in mechanical constrains.
Spinning disc can be realized:
 - With precise motor connected to the hub with belt - popular in early-80s drives, it usually has black and white bars for stroboscope diagnostics.
 - With motor attached with its coils to PCB, used to drive the shaft directly - popular in most later drives, but harder to service. Later units allowed to easily switch between 300 and 360RPM without long callibration.
Moving heads is usually done with:
 - Stepper motor pushing head carrier with piece of metal tape. The motor can be installed with shaft horizontally (usually) or vertically, perpendicular to head carrier moving axis.
 - Stepper motor with shaft covered by worm screw, this screw pushes/pulls head carrier - shaft is installed parallel to head moving axis. This technology was used to made smallest drives.
 - Stepper motor equipped with a large horizontally-placed wheel, in which the same worm screw is cut-in. It's used to move head. Used mostly with success in early German drives, used with less success in Eastern European drives (as the worm cut was not deep enough).
Some later drives have additional solenoid which is used do drop heads to the surface of the disc when disc is used and lift heads after operation. Its action is easy to hear, as it emits quite loud click when heads are dropped or lifted.
    And don't forget about drive electronics. There are usually some jumpers or pads. The must-have is drive number, which, in PC, must be always set to DF1 (D1, DRIVE1, ID1 or just 1 in 4-jumper block numbered starting with 0), even in two-drive systems. There are more jupers, TEAC Manuals usually describe them, other drives use similar descriptions. Many times you can see FG jumper which shorts electronics ground to metal frame ground.  INUSE or IU turns pin 4 of connector to IN USE signal. ML - decides should drive motor be activated by MOTOR signal in interface cable, or is it only for disk-in-use information purposes. RY/DC is commonly used to decide should line 34 of connector be used as READY signal or DISK CHANGE signal.
More rare jumpers:  U0 and U1 jumpers are rare, they allow to invert drive LED signal and to decide whether LED should be turned on (usually some combos of DRIVE SELECT, IN USE and READY signal, with OR or AND between). LG - Inverts LOW/HIGH density selection signal line.
Some rare drives use I and IS jumpers to set speed. If I is set, drive uses dual-speed: 360rpm for high density and 300rpm for low. If I and IS are off, drive spins 360rpm. If both are on, drive goes dual-speed, but remains in ready state after changing format by DENSITY line.
E2 - even more rare, used sometimes in hard-sectored drives. Controls index line of drive.
 

Here are few disk drives discussed:
Alps DFC222B02A
Density: Double (360K in PC)
Jumpers not described well. Disc motor board described very well, you can see which connections are for which function, making it theoretically possible to alter drive speed. Head assembly covered by piece of metal.
Locking mechanism: Turning lever.
Head moving mechanism: Stepper motor (shaft horizontally) + steel tape, shaft perpendicular to head moving direction.
Spinning mechanism: Motor in PCB.
Electronics close-up Connections are well labeled here... Notice white termination resistors in socket

 
Chinon FZ-502
Density: Double (360K in PC)
Jumpers not described well, visible on the side of PCB. Head assembly and whole upper part covered by piece of metal.
Locking mechanism: Turning lever.
Head moving mechanism: Stepper motor moving head carrier, shaft located vertically.
Spinning mechanism: Motor in PCB.
 
Notice head moving motor Connector piece  

 
Digital DS-53A
Density: Double (360K in PC)
Jumpers accessible by cut-out in metal shielding. Head assembly and whole upper part covered by piece of metal.
Locking mechanism: Turning lever.
Head moving mechanism: Stepper motor + metal belt, with shaft vertically (pic. below) 
Spinning mechanism: Motor in PCB.

General view Electronics with SMD components Rear

 
NEC FD-1157C
Density: High (1.2MB PC)
Only simple jumpers. Head mechanism lifted and dropped by solenoid, it makes loud clicks which is normal. Upper assembly covered by piece of metal. Upper head has its own metal protective cap, glued with piece of foam. This piece may fall apart letting protective cap fall to the mechanical part - check it before testing drive!
Locking mechanism: Turning lever.
Head moving mechanism: Stepper motor moving head carrier with metal belt, shaft located horizontally.
Spinning mechanism: Motor in PCB.

Technical parameters on NEC website.

Notice the solenoid - metal cylinder with blue label near head carrier.  

 
Canon MD5501
Density: High (1.2MB PC)
Only simple jumpers (DRIVE ID). Upper assembly should be covered by piece of metal, but it isn't in my unit. Drive was available with normal and low-profile panel to use in small computers. It's generally low-profile drive, it's half high as normal, making it 1/4 of standard full 5.25" height (full height is 2 typical drives).
Locking mechanism: Button.
Head moving mechanism: Stepper motor with worm screw shaft parallel to head moving direction.
Spinning mechanism: Motor in PCB.
If you really want to see the jumper settingsm look at this document.
 
Electronics is mainly in SMD, as the drive must be small.   Canon MD5501 with low-profile panel in case with AC power supply, as external FDD for Compaq laptop.

 
TEAC FD-55GFR
Density: High (1.2MB PC)
Very popular drive manufactured with different front panels, LED colors and shapes. Jumpers as in TEAC drives - many soldered, many not. Manual can explain some of them. Upper assembly not protected by any metal shielding.
Locking mechanism: Turning lever.
Head moving mechanism: Stepper motor, metal belt, shaft horizonatlly.
Spinning mechanism: Motor in PCB.
Index hole electronics (?for hard-sectored disks?) not soldered. Electronics PCB is very small.  
<- Exact view of front panel.  

 
Mera-KFAP ED-516
Density: High (1.2MB PC)
Similar to early TEAC and Robotron products. Jumpers - mostly unknown. Built around western components, assembled in KFAP in Kraków, Poland. Notice two-color LED in front panel - it lighs red when 360K disks are used or green with 1.2MB disks.
Locking mechanism: Turning lever.
Head moving mechanism: Stepper motor, metal belt, shaft horizonatlly.
Spinning mechanism: Motor in PCB.
 Schematic of ED-516
Electronics is like in TEAC drives. One SMD component, rest is through-hole Export version has Russian description.

 
Mera-KFAP ED-510
Density: Double (360KB PC)
Similar to early TEAC and Robotron products. Jumpers - mostly unknown. Built around western components, assembled in KFAP in Kraków, Poland. Red LED only.
Locking mechanism: Turning lever.
Head moving mechanism: Stepper motor, metal belt, shaft horizonatlly.
Spinning mechanism: Motor in PCB.
 Schematic of ED-510


Assembling FDDs in KFAP, Kraków, Poland.

Electronics similar to 516 model Copare with electronics of 516. Some chips are missing, but board is the same. Russian description, no CM (Unified System) number now.

 

 
Mera-KFAP ED-505
Density: Double (360KB PC)
Similar to early TEAC and Robotron products, electronics is more robust than in  later ED-510 model. Jumpers - mostly unknown. Built around western components, assembled in KFAP in Kraków, Poland. Red LED only.
Locking mechanism: Turning lever.
Head moving mechanism: Stepper motor, metal belt, shaft horizonatlly.
Spinning mechanism: Motor in PCB.
.
 Schematic of ED-505
 
Upper part is not different than 510 Compare with 510 - more through-hole chips, not SMD. Russian description, but CM (SM) number in latin, not in cyrilic.

 

 

 

 
IZOT EC5088 M1
Density: Low, single-sided!
Soviet Union computers were equipped with these. They were unreliable because worm screw was not deep enough. In Poland it was used in some Soviet measuring devices, in Soviet Union in Agat computers. Interface more or less compatible with typical one, but as in all Eastern block equipment connector and pinout is different. "M1" had 40 tracks, while "M" had 35. Made in Bulgaria.
Locking mechanism: Flap.
Head moving mechanism: Stepper motor, worm screw in a horizontally-placed disc.
Spinning mechanism: Motor and typical belt transmission.
Unfortunately documentation I got was incomplete, most parts were missing. All things I got are: Parts Catalog, Parts change, Warranty card and Errata (all in DJVU format).
Here are two files from Internet, I don't know where I found it: Manual, Some FDC manual with pinout (using different connector than my unit, but there are signals described).
I think I don't have to say that's in Russian :).
As it came to me Flap closed Flap opened
Electronics with Soviet components Motor driving electronics. Bottom - belt transmission and head motor
Manuals and connectors shipped with unit. After removing electronics - visible head carrier assembly. Details of head moving assembly. More detailed photo can be seen here.

 

Some other drives:

BASF unit used in Commodore PC-10. Very quiet mechanics. Another 360K BASF unit, with worm-screw disc head driving and strange locking mechanism. Works well in old PC.
 
Drives in Siemens PC/X, one of first European PCs. Floppy disks accessories and stuff.