Floppy Disk Drives

Introduction

IBM released the first floppy disk drive in 1972 - these used 8" floppy disks. In 1976 the 5¼" floppy disk, the "minifloppy", was made available. The drives were manufactured by Shugart Associates initially, but by 1978 there were over 10 manufacturers producing 5¼" floppy drives in competing physical disk formats: hard-sectored (90 KB) and soft-sectored (110 KB). Before long, the hard-sectored format disappeared.

The first IBM PC was envisioned with a cassette tape, but typically it came with one or two 5¼" floppy disk drives. The idea behind having more than one drive was so that you could have your 'Program' disk in one, and your 'Working Files' disk in another. In the earliest PCs these drives were "full-height", meaning they took up two drive bays - one on top of the other. In 1986 the IBM PC XT was made available which introduced the "half-height" drive which took up just one drive bay. This allowed the XT to have two floppy drives plus a full-height hard drive.

The original IBM 5150 Personal Computer with two 5¼" floppy disk drives IBM PC-XT with two 5¼" half-height floppy disk drives and a hard disk drive

Physical Disk Geometry

A floppy disk is essentially a very flexible piece (hence the term floppy disk) of plastic coated on both sides in a magnetic material. This 'disk' of plastic is contained within a protective envelope or hard plastic case, which is then inserted into the drive and automatically locked onto a spindle. It is then rotated at a constant speed (360 rpm for standard PC floppy drives) by means of a spindle motor. A head assembly consisting of two magnetic read/write heads, one in contact with the upper surface of the disk and one in contact with the lower surface of the disk, may be moved in discrete steps across the disk by means of a stepper motor.

A diagram showing the various terms used to desribe a disk's geometry

Due to the location of the head assembly and the fact the disk is spinning means the area of magnetic material that is passing under the upper head is seen to be a very narrow circular strip - this is called a track. Because there is both a track on the upper side of the disk and the lower side of the disk, both tracks together are called a cylinder. The number of possible cylinders for a given drive is clearly determined by the number of discrete steps available to the stepper motor. In practice, a track is considered too large a unit for storing information, so it is divided into sectors. Typically, each sector stores 512 bytes of data. The diagram above shows 9 sectors, which is typical of older 5¼" floppy disks. Later ones use 15 sectors per track, whilst the standard 3½" 1.44 MB floppy disk has 18 sectors per track. Cylinder numbers are the same as track numbers - they represent the position of the head assembly. The number of heads, tracks and sectors per track a drive has is called its geometry. If you multiply the number of heads by the number of tracks by the number of sectors per track a disk has, you will find how many sectors a given disk has. Multiplying that number by 512 will give you the total capacity in bytes.

For example:

A 5¼" double-sided low-density floppy disk has 9 sectors and 40 tracks per side, so 80 tracks in total if you count both the upper and lower side of the disk, so to calculate the total capacity:

9 x 80 = 720 [total sectors]
720 x 512 [bytes] = 368,640
368,640 / 1024 = 360 KB (kilobytes)

This same logic above works just as well for hard disks as it does for floppy disks, except a hard disk will contains multiple heads, whereas a floppy drive has just one head.

Storage Capacities

The first PC 5¼" floppy disks were single-sided, capable of storing 160 KB. In 1982 MS-DOS v1.1 added support for double-sided disks, increasing capacity to 320 KB (160 KB on each side). These disks allowed for 48 tracks per inch - after formatting they contained a total of 40 tracks with 8 sectors per track, and each sector could store 512 bytes. The formula for calculating disk capacity is:

(bytes per sector) x (sectors per track) x (number of tracks)

e.g. 512 x 8 x 40 = 163,840 bytes (160 KB) x two sides = 320 KB

By 1983 and the introduction of DOS 2.0, support for 9 sectors per track arrived, which provided two more capacities: 180 KB (single-sided) and 360 KB (double-sided). Then, coinciding with the launch of the IBM PC/AT in 1984, came high-density disks which used 96 tracks per inch. This meant a formatted 5¼" floppy disk could now hold 1,200 KB (1.2 MB) of data. High-density drives could also read double-density floppy disks, which permitted owners of older media to be able to upgrade without concern. These new high-density drives in the IBM were typically the Y-E Data model YD-380. If a customer opted for a low-density drive with their AT, they would have Y-E Data model YD-580, which supported up to 360 KB disks.

Meanwhile, 3½" floppy disks, known as "microfloppy" and first invented by Sony, had been introduced in 1983. For the IBM PC world, these started off as single-sided double-density (SS/DD), which gave a formatted capacity of 360 KB - the same as a double-sided 5¼" floppy disk. Very soon after, double-sided double-density (DS/DD) 3½"disks were made available, giving a formatted capacity of 720 KB. In 1987, "high"-density disks arrived which doubled this capacity to 1.44 MB. These required a high-density 3.5" drive drive to make use of the additional storage capability.

In short, the following formats were commonplace in the PC world from 1983 to the early 2000s:

Physical Size Sides/Density Formatted Capacity
5¼"   Double-Sided, Double-Density (DS/DD) 360 KB
5¼"   Double-Sided, High-Density (DS/HD) 1.2 MB
3½"  Double-Sided, Double-Density (DS/DD) 720 KB
3½"  Double-Sided, High-Density (DS/HD) 1.44 MB

High-density floppy disks were so ubiquitous throughout the 80s and into the 90s partly due to the high relative cost of hard disk drives at the time - in 1989 the typical hard disk drive ranged from 20 MB up to 80 MB with an entry-level price point of £170 for 20 MB. This compared to 5¼" high-density floppies which sold in boxes of 10 for £14 (£1 per MB for floppy storage vs £8.50 per MB for a hard disk). In the U.S., prices were similar (1.56:1 exchange rate at the time) - a 20 MB hard disk drive went for $260 whilst a box of 10 floppies was $12.

The Floppy Drive Cable

The standard PC floppy drive cable has several connectors, usually either 3 or 5. The connector furthest away from the others connects to the 'host' (the motherboard header or your floppy disk controller header). There are then either 1 or 2 pairs of connectors - these are used to support either a 3.5" floppy drive or a 5.25" floppy drive. It is not advisable to use both connectors in a single pair - this is the reason for having the second pair.

You may also notice the cable has a "twist" before the last pair of connectors. This is used to determine which drive [in a multi-drive] system is drive 'A' or 'B' [also called drive '1' or '2']. From the pin out table below; the swapped pins determine the "floppy drive enabled" flag, and which drive motor is enabled. The pins are line 10, line 12, line 14, and line 16, while the other lines in the twist are ground lines.

This twisted cable idea came about as a convenience, as it meant PC builders didn't need to fiddle with the floppy drive jumpers for each customer's configuration. Back when floppy drives were prevalent, customers chose either a single or dual floppy drive, since hard disks were so expensive.

All floppy drives were factory-configured as Drive B: - any signals that went to the last pair of connectors (after the twist) got their signals reversed so the drive motor and 'floppy enable' signal would be interpreted as Drive A: due to the twist.

Here are the pinouts of the cable:

Floppy Drive A/B Twist Pinout
-- Host/Controller Drive A Drive B Description
Wire 1-9 1-9 1-9 1-9 No Change
Wire 10 10 16 10 Motor Enable Drive 0/1
Wire 11 11 15 11 Ground, No Change
Wire 12 12 14 12 Drive Select 0/1
Wire 13 13 13 13 Ground, No Change
Wire 14 14 12 14 Drive Select 0/1
Wire 15 15 11 15 Ground, No Change
Wire 16 16 10 16 Motor Enable Drive 0/1
Wire 17-34 17-34 17-34 17-34 No Change

 

The 2.88 MB Floppy

A 2.88 MB floppy drive was developed by Toshiba (and manufactured by Mitsumi) in the late 1980s for IBM's new PS/2 range, but failed to catch on in large numbers outside of IBM. These drives employed a very tightly-packed 36 sectors per track, and required special "ED" (Extra Density) 2.88 MB disks to work. These look almost identical to high-density 3.5" floppy disks, but have an "ED" symbol and have their "media sensing" hole further down from the top-left corner than on a high-density disk - this allows 2.88 MB drives to recognise when ED media has been inserted.

One recognised contributing factor to this format not being widely accepted by other manufacturers is that the floppy disk controller needed to support a transfer speed of 1 Mbps (most could only cope with a maximum transfer speed of 256 Kbps on 720 KB drives and 500 Kbps on 1.44 MB drives). Since this meant a new controller card would be needed as well as the floppy drive itself, the cost of a PC manufacturer moving to the 2.88 MB floppy format was prohibitive.

IBM first fitted 2.88 MB floppy disk drives to their PS/2 Model 50, 60, 70 and 80 ranges. The drives had no separate power connector - instead the ribbon cable also supplied power to the drive. Some of these drives that were sold independently of an IBM PS/2 came with an adapter that converted the FDD interface from the proprietary IBM floppy interface to a standard 2-row 34-pin FDD connector and separate power connector. Even if your PC's BIOS supports 2.88 MB floppy drives, you still need this adapter for the drive to function.

3.5" Floppy Drives with Edge Connector

Some early IBM PS/2s and other PCs had 3.5" floppy disk drives that had a 40-pin edge connector instead of the later 34-pin 2-row header. These include the PS/2 Model 50, 60, 70 and 80. These older drives require an adapter or special cable that converts its 40-pin edge connector to a 34-pin header.

These 40-pin edge connectors are NOT the same as those used by 5.25" floppy drives, as the IBM drives had their power supplied through this interface.

The make a cable that connects the 40-pin edge connector to a 34-pin header connector, use this diagram:

Cable to convert 40-pin edge connector to a 34-pin header connector:

Edge connector pin Header connector pin Signal
1 1 Ground
2 2 -High Density Select
3 NC Reserved
4 4 Drive Type ID 1
5 5 Ground
6 NC Reserved
7 7 Ground
8 8 -Index
9 9 Ground
10 10 Reserved
11 11 Ground
12 12 -Drive Select
13 13 Ground
14 14 Reserved
15 15 Ground
16 16 -Motor Enable
17 17 Ground
18 18 -Direction In
19 19 Ground
20 20 -Head Step
21 21 Ground
22 22 -Write Data
23 23 Ground
24 24 -Write Enable
25 25 Ground
26 26 -Track 0
27 27 Ground
28 28 -Write Protect
29 29 Ground
30 30 -Read Data
31 31 Ground
32 32 -Head 1 Select
33 33 Ground
34 34 -Diskette Change
35 NC Ground
36 NC Ground
37 NC Ground
38 3 +5V DC
39 NC Ground
40 6 +12V DC

*NC = Not Connected

 

By 1993, PC compatibles were being sold with 3½" floppy drives made by the following manufacturers:

Y-E Data was a wholly owned subsidiary of the Yaskawa Electric Corporation, in Otsuka, Japan. Y-E Data Inc (YED) began in September 1973 and was one of the first Japanese businesses to venture into computer peripherals. They saw IBM's move from punched cards to floppy disk drives and imported technology from an American company called Orbis, Inc. Initially they simply resold the Orbis 8" single-sided drive domestically. It was capable of storing 128 KB on a disk. In 1974, they designed and produced their own floppy disk drive, the YD-74C - this was also an 8" single-sided drive. It was followed in 1977 with an 8" double-sided drive, model YD-174. In 1978 their first 5.25" floppy drive was launched - model YD-274. Their first 3.5" drive would arrive much later in 1987 - the YD-800 series. The C-series was designed for portables. A later F-series arrived in 1989. These were 'slim', and had models YD-3042 and YD-3082. Y-E Data continued to produce floppy drives into the late 1990s when there was a shift to the USB interface for these drives.

Mfr

Model Image Specs Notes/comments
Canon 221   5.25", Double Sized, Double Density 720 KB Half-height internal desktop drive
Canon 530   5.25", Double Sized, Double Density 720 KB Half-height internal desktop drive
Canon MDD531 5.25", Double Sided, Double Density 360 KB Half-height internal desktop drive
Canon 3361   3.5", Double Sided, High Density 1.44 MB Half-height internal desktop drive
Canon 5201   5.25", Double Sided, Double Density 360 KB Half-height internal desktop drive
Canon MD5501 5.25", Double Sided, High Density 1.2 MB Half-height internal desktop drive. Also available in black with same model number.
Canon MD5511 Dual 5.25" 1.2 and 3.5" 1.44 MB drive Half-height internal desktop drive
Chinon FZ-357

3.5" 1.44 MB, DS/HD

Internal desktop drive. Similar model is the FG-357.
Chinon FZ-502

5.25" 360 KB, DS/DD

Internal desktop drive. Also available in black.
Chinon FZ-506

5.25" 1.2 MB, DS/HD

Internal desktop drive. Similar model is FR-506.
Chinon 506-L  

5.25" 1.2 MB, DS/HD

Internal desktop drive
Citizen OSDA-01D   3.5" 720K, Double Sided, Double Density Internal desktop drive
Citizen OSDA-14A   3.5", Double Sided, High Density Internal desktop drive
Citizen OSDA-39D   3.5", Double Sided, High Density Internal desktop drive
Citizen OSDA-51B (Compaq)   3.5", Double Sided, High Density Internal desktop drive
Citizen OSDA-52B (Compaq)   3.5", Double Sided, High Density Internal desktop drive
Citizen OSDA-53B (Compaq) 3.5", Double Sided, High Density Internal desktop drive
Citizen OSDA-77D   3.5", Double Sided, Double Density Internal desktop drive
Citizen OSDA-81F   3.5", Double Sided, High Density Internal desktop drive
Citizen OSDA-90E-U 3.5", Double Sided, Double Density Internal desktop drive. Similar model is OSDA-90G-U.
Citizen OPDB-22A   3.5", Double Sided, Double Density Internal desktop drive
Citizen OSDD-05B   3.5", Double Sided, Double Density Internal desktop drive
Citizen OSDD-57   3.5", Double Sided, Double Density Internal desktop drive
Citizen OSDD-57B   3.5", Double Sided, Double Density Internal desktop drive
Citizen U1DA-14A   3.5", Double Sided, High Density

Laptop drive

Citizen V1DA-10A   3.5", Double Sided, High Density Laptop drive
Citizen V1DA-27A   3.5", Double Sided, High Density Laptop drive
Citizen V1DA-31B   3.5", Double Sided, High Density Laptop drive
Citizen V9DA-55A   3.5", Double Sided, High Density Laptop drive
Citizen V9DA-55B   3.5", Double Sided, High Density Laptop drive
Citizen V9DA-71B   3.5", Double Sided, High Density Laptop drive
Epson 170-SMD   3.5", Single Sided, Double Density 400 KB Half-height
Epson 180   3.5", Double Sided, Quad Density 720 KB Half-height
Epson 200P-053   3.5", Double Sided, Quad Density 720 KB Half-height
Epson 200P-055   3.5", Double Sided, Quad Density 720 KB Half-height
Epson 200P-073   3.5", Double Sided, Quad Density 720 KB Half-height
Epson 280   3.5", Double Sided, Quad Density 720 KB Half-height
Epson SMD-300 3.5", Double Sided, High Density 1.44 MB Half-height
Epson SD321 5.25", Double Sided, Double Density 360 KB Half-height
Epson SMD340 3.5", Double Sided, High Density 1.44 MB Half-height
Epson 400 W/Frame   3.5", Double Sided, High Density 1.44 MB Half-height
Epson 400P-4   3.5", Double Sided, High Density 1.44 MB Half-height
Epson SD-500 5.25", Double Sided, Double Density 360 KB Half-height
Epson 521   5.25", Double Sided, Double Density 360 KB Half-height
Epson 521L   5.25", Double Sided, Double Density 360 KB Half-height
Epson SD600 5.25", Double Sided, Double Density 360 KB Half-height
Epson SD621L 5.25", Double Sided, Double Density 360 KB Half-height
Epson SD680L 5.25", Double Sided, High Density 1.2 MB Half-height. Also sold in grey.
Epson SD-700/800 Dual 5.25" and 3.5" high density Half-height
Epson 1000   3.5", Double Sided, High Density 1.44 MB Laptop drive
Epson 1000P   3.5", Double Sided, High Density 1.44 MB Laptop drive
Epson SMD-1100 3.5", Double Sided, High Density 1.44 MB Half-height.
Epson SMD-1300 3.5", Double Sided, High Density 1.44 MB Half-height. Similar to SMD-1340.

Hitachi

HFD 305S

  5.25", Single-Sided Double Density 360 KB Internal desktop drive

Hitachi

FD532EIU

  5.25", Double-Sided High Density 2.4 MB Internal desktop drive

Hitachi

FDD412A

  5.25", Double-Sided High Density 1.2 MB Internal desktop drive

Mitsubishi

353AF   3.5" 720 KB Internal desktop drive

Mitsubishi

353B-12   3.5" 720 KB Internal desktop drive

Mitsubishi

353B-82   3.5" 720 KB Internal desktop drive

Mitsubishi

353C   3.5" 720 KB Internal desktop drive

Mitsubishi

353-12   3.5" 720 KB Internal desktop drive
Mitsubishi 355B-52   3.5" Double Sided, High Density Internal desktop drive
Mitsubishi 355B-82UF   3.5" Double Sided, High Density Internal desktop drive
Mitsubishi 355B-88UF   3.5" Double Sided, High Density Internal desktop drive
Mitsubishi 355BA-82UF/W51/4   3.5" Double Sided, High Density Internal desktop drive
Mitsubishi 355BA-88UF/W51/4   3.5" Double Sided, High Density Internal desktop drive
Mitsubishi 355C-12   3.5" Double Sided, High Density Internal desktop drive
Mitsubishi 355C-37/W51/4   3.5" Double Sided, High Density Internal desktop drive
Mitsubishi 355C-58UF   3.5" Double Sided, High Density Internal desktop drive
Mitsubishi 355C-82UF/W51/4   3.5" Double Sided, High Density Internal desktop drive
Mitsubishi 355C-88UF/W51/4   3.5" Double Sided, High Density Internal desktop drive
Mitsubishi 355C-215   3.5" Double Sided, High Density Internal desktop drive
Mitsubishi 355C-222   3.5" Double Sided, High Density Internal desktop drive
Mitsubishi 355C-258MC   3.5" Double Sided, High Density Internal desktop drive
Mitsubishi 355C-352   3.5" Double Sided, High Density Internal desktop drive
Mitsubishi 355C-526   3.5" Double Sided, High Density Internal desktop drive
Mitsubishi 355C599MA (PS/2)   3.5" Double Sided, High Density Internal desktop drive
Mitsubishi 355C599MB (PS/2)   3.5" Double Sided, High Density Internal desktop drive
Mitsubishi 355C599MQ41 (PS/2)   3.5" Double Sided, High Density Internal desktop drive
Mitsubishi 355C599MQ4 (PS/2)   3.5" Double Sided, High Density Internal desktop drive
Mitsubishi MF355F258 3.5" Double Sided, High Density Internal desktop drive
Mitsubishi 355W99M1 (PS/2)   3.5" Double Sided, High Density Internal desktop drive
Mitsubishi MF501A/B/C   5.25" Double Sided, Double Density Internal desktop drive
Mitsubishi MF503   5.25" Double Sided, Quad Density (720K) Internal desktop drive
Mitsubishi MF504A/B/C/S   5.25" Double Sided, High Density Internal desktop drive
Mitsumi D359C 3.5", Double Sided, High Density 1.44 MB Laptop drive
Mitsumi D359T2   3.5", Double Sided, High Density 1.44 MB Half-height
Mitsumi D359T3   3.5", Double Sided, High Density 1.44 MB Half-height
Mitsumi D359T5 3.5", Double Sided, High Density 1.44 MB Half-height
Mitsumi D503   5.25", Double Sided, Double Density 360 KB Half-height
Mitsumi D509V   5.25", Double Sided, High Density 1.2 MB Half-height
NEC 1035   3.5", Double Sided, Double Density 720 KB Half-height
NEC 1036A   3.5", Double Sided, Double Density 720 KB Half-height
NEC 1037A   3.5", Double Sided, Double Density 720 KB Half-height
NEC 1053   5.25", Double Sided, Double Density 360 KB Half-height
NEC 1055   5.25", Double Sided, Double Density 720 KB Half-height
NEC 1137H   3.5", Double Sided, High Density 1.44 MB Half-height
NEC 1155C   5.25", Double Sided, High Density 1.2 MB Half-height
NEC 1157C   5.25", Double Sided, High Density 1.2 MB Half-height
NEC 1158C   5.25", Double Sided, High Density 1.2 MB Half-height
NEC 1165A   8.0", Double Sided, Double Density 160 KB Half-height
NEC 1165FQ   8.0", Double Sided, Double Density 160 KB Half-height
NEC 1165F   8.0", Double Sided, Double Density 160 KB Half-height
NEC 1165H   8.0", Double Sided, Double Density 160 KB Half-height
NEC 1165S   8.0", Double Sided, Double Density 160 KB Half-height
NEC 5138A   3.5", Double Sided, High Density 1.44 MB Half-height
Sony 17W   3.5", Double Sided, High Density 1/3rd-height desktop drive
Sony 17W-5PF (SUN)   3.5", Double Sided, High Density 1/3rd-height desktop drive
Sony 17W-10   3.5", Double Sided, High Density 1/3rd-height desktop drive
Sony 17W-34   3.5", Double Sided, High Density 1/3rd-height desktop drive
Sony 17W-42   3.5", Double Sided, High Density 1/3rd-height desktop drive
Sony 17W-WFP (SUN)   3.5", Double Sided, High Density 1/3rd-height desktop drive
Sony 17W-90 (Compaq)   3.5", Double Sided, High Density 1/3rd-height desktop drive
Sony 40W-00 (PS2)   3.5", Double Sided, High Density 2.88 MB 1/3rd-height desktop drive
Sony 40W-9E   3.5", Double Sided, High Density 2.88 MB 1/3rd-height desktop drive
Sony 53W   3.5", Double Sided, Double Density 720 KB 1/3rd-height desktop drive
Sony 63W   3.5", Double Sided, Double Density 720 KB 1/3rd-height desktop drive
Sony 73W   3.5", Double Sided, High Density 3/4-height
Sony 73W-34D   3.5", Double Sided, High Density 3/4-height
Sony 75W (Apple)   3.5", Double Sided, High Density Half-height internal desktop drive
Sony 77W (PS2)   3.5", Double Sided, High Density Half-height internal desktop drive
Sony 120-04   3.5", Double Sided, High Density 1/3rd-height desktop drive
Sony 420-6   3.5", Double Sided, High Density 1/3rd-height desktop drive
Tandon TM-100-1(A) 5.25" Single-Sided, Double Density Full-height desktop drive, used in the IBM PC (Model 5150)
Tandon TM-100-2(A) 5.25" Double-Sided, Double Density Full-height desktop drive, used in the IBM PC/XT (Model 5160)
Tandon TM-100-3      
Teac 35F   3.5", Double Sided, Double Density Internal desktop drive
Teac 35FN   3.5", Double Sided, Double Density Internal desktop drive
Teac 35HFN   3.5", Double Sided, High Density Internal desktop drive
Teac 53B   5.25", Double Sided, Double Density Internal desktop drive
Teac 54B   5.25" - Unknown specs Internal desktop drive, found in Sanyo MBC-55X
Teac 55A   5.25", Single-Sided, Double Density Internal desktop drive, found in Sanyo MBC-55X
Teac 55B   5.25", Double Sided, Double Density Internal desktop drive, found in Sanyo MBC-55X
Teac 55BR   5.25", Double Sided, Double Density Internal desktop drive
Teac 55BV   5.25", Double Sided, Double Density Internal desktop drive
Teac 55FR   5.25", Double Sided, Double Density Internal desktop drive
Teac 55FV   5.25", Double Sided, Double Density Internal desktop drive
Teac 55G   5.25", Double Sided, High Density Internal desktop drive
Teac 55GFR 5.25", Double Sided, High Density Internal desktop drive
Teac 55GV   5.25", Double Sided, High Density Internal desktop drive
Teac 55GFV   5.25", Double Sided, High Density Internal desktop drive
Teac 55GVF   5.25", Double Sided, High Density Internal desktop drive
Teac 135FN   Double Sided, Double Density Internal desktop drive
Teac 135HF   3.5", Double Sided, High Density Internal desktop drive
Teac 135HFN   3.5", Double Sided, High Density Internal desktop drive
Teac FD-235F   3.5", Double Sided, Double Density Internal desktop drive
Teac FD-235HF 3.5", Double Sided, High Density Internal desktop drive
Teac FD-505 5.25", Double Sided, Double Density Internal desktop drive
Teac 05HF-030 3.5", Double Sided, High Density Laptop drive
Teac 05HF-532U   3.5", Double Sided, High Density Laptop drive
Toshiba 0202A   5.25", Double Sided, Double Density 720 KB Full-height drive
Toshiba 0242A   5.25", Double Sided, Double Density 360 KB Half-height drive
Toshiba 0401GR   5.25", Double Sided, Double Density 360 KB Half-height drive
Toshiba 0801GR   5.25", Double Sided, High Density 1.2 MB Half-height drive
Toshiba 0802GR   5.25", Double Sided, High Density 1.2 MB Half-height drive
Toshiba 352TH   3.5", Double Sided, Double Density 720 KB Half-height drive
Toshiba 3527H   3.5", Double Sided, Double Density 720 KB Half-height drive
Toshiba 3527TH   3.5", Double Sided, Double Density 720 KB Half-height drive
Toshiba 3561   3.5", Double Sided, High Density 1.44 MB Half-height drive
Toshiba 3564   3.5", Double Sided, High Density 1.44 MB Half-height drive
Toshiba 3567   3.5", Double Sided, High Density 1.44 MB Half-height drive
Toshiba 4210   3.5", Double Sided, Double Density 720 KB Half-height drive
Toshiba 4202-AOK   3.5", Double Sided, Double Density 720 KB Half-height drive
Toshiba 4207-AOK   3.5", Double Sided, Double Density 720 KB Half-height drive
Toshiba 4207-AOK   3.5", Double Sided, Double Density 720 KB Half-height drive
Toshiba 4261   3.5", Double Sided, Double Density 720 KB Half-height drive
Toshiba 4449-AOZ (PS/2)   3.5", Double Sided, Double Density 720 KB Half-height drive
Toshiba 5401   5.25", Double Sided, Double Density 360 KB Half-height drive
Toshiba 5406   5.25", Double Sided, Double Density 360 KB Half-height drive
Toshiba 5426   5.25", Double Sided, Double Density 360 KB Half-height drive
Toshiba 5451   5.25", Double Sided, Double Density 360 KB Half-height drive
Toshiba 5454   5.25", Double Sided, Double Density 360 KB Half-height drive
Toshiba 5471   5.25", Double Sided, Double Density 360 KB Half-height drive
Toshiba 5472   5.25", Double Sided, Double Density 360 KB Half-height drive
Toshiba 5474   5.25", Double Sided, Double Density 360 KB Half-height drive
Toshiba 5629   5.25", Double Sided, Double Density 720 KB Half-height drive
Toshiba 5861   5.25", Double Sided, High Density 1.2 MB Half-height drive
Toshiba 5863   5.25", Double Sided, High Density 1.2 MB Half-height drive
Toshiba 5881   5.25", Double Sided, High Density 1.2 MB Half-height drive
Toshiba 5882   5.25", Double Sided, High Density 1.2 MB Half-height drive
Toshiba 6371   5.25", Double Sided, Double Density 360 KB Half-height drive
Toshiba 6374   5.25", Double Sided, Double Density 360 KB Half-height drive
Toshiba 6471   5.25", Double Sided, Double Density 360 KB Half-height drive
Toshiba 6474-T2P   5.25", Double Sided, Double Density 360 KB Half-height drive
Toshiba 6782   5.25", Double Sided, High Density 1.2 MB Half-height drive
Toshiba 6784   5.25", Double Sided, High Density 1.2 MB Half-height drive
Toshiba 6881   5.25", Double Sided, High Density 1.2 MB Half-height drive
Toshiba 6882   5.25", Double Sided, High Density 1.2 MB Half-height drive
Toshiba 6890   5.25", Double Sided, High Density 1.2 MB Half-height drive
Toshiba BR505930-2   3.5", Double-Sided, Double-Density 720 KB Found in IBM PC Convertible (Model 5140)
Toshiba ND-3565-A   3.5", Double Sided, High Density 1.44 MB Half-height drive
Toshiba ND-356T-A   3.5", Double Sided, High Density 1.44 MB Half-height drive
Toshiba M48D-12   5.25", Double Sided, Double Density 360 KB Half-height drive
YE-Data YD-74C   8" SS/SD 128 KB Launched in 1974
YE-Data YD-174 8" DS Launched in 1977
YE-Data YD-180 8" slim, Double-sided, double-density 160 KB Launched in 1981. Half-height internal drive.
YE-Data YD-274   5.25" DS/DD 360 KB Launched in 1978
YE-Data YD-280 5.25" DS/DD 360 KB Launched in 1981. Full-height drive. Report of this being a 720 KB drive?
YE-Data YD-380 5.25" slim DS/HD 1.2 MB Launched in 1982. Supplied with the IBM PC/AT.
YE-Data YD-380B   5.25" slim DS/HD 1.2 MB Launched in 1982.
YE-Data YD-380C 5.25" slim DS/HD 1.2 MB

Note the lack of the 'lip' around the drive entry compared to the YD-380.

A black version called YD-380T was also produced - the light and arm were reversed on the 380T.

YE-Data YD-480   5.25" slim Launched in 1983.
YE-Data YD-580
YD-580B
5.25" DS/DD 360 KB Launched in 1983. Supplied with the IBM PC/AT (also in late PC/XT)
YE-Data YD-625 5.25" DS/HD Launched in 1997.
YE-Data YD-665C
YD-666C
3.5"  
YE-Data YD-800
YD-3540
  3.5" DS/HD Launched in 1987.
YE-Data YD-3042   3.5" DS/DD 720 KB Launched in 1988.
YE-Data YD-3082   3.5" DS/HD 1.44 MB Launched in 1988.
YE-Data YD-742   3.5" 4MB Launched in 1990.
YE-Data YD-700B series   5.25" and 3.5" double-speed drives Launched in 1991. YD-700B is 1" height. YD-702G is slim.
YE-Data YD-701 3.5" 1.44 MB Two IBM PS/2 versions were also created - one which had an edge connector and a second that had pin edge.
YE-Data YD-750   3.5" large capacity (20MB) floppy drive (SCSI). Launched in 1992.
YE-Data YD-702D 3.5" Internal desktop drive-height 1.44 MB. Launched in 1993.
YE-Data YD-702J Super-slim 3.5" FDD for laptops. Launched in 1993.
YE-Data ?   3.5" double-speed drives - new series Launched in 1995.
YE-Data ?   3.5" Double-speed drives. Launched in 1996.
YE-Data YD-802 5.25" DS/HD Produced in 1997.
YE-Data YD-8U10,
YD-8U12, YD-8U14
  USB interface floppy drive. Launched in 1998.

 

Frequently Asked Questions

Q) Can I get a 5.25" floppy drive connected via USB to a modern PC?

A) Yes! A company called Device Side Data have a product called the FD5025 USB 5.25" floppy controller. One great thing about this interface is that it works with not just PC drives, but also Apple, Commodore, Texas Instruments, Atari and more, and comes with Windows and Mac OS software to pull data off your disks for archival purposes! It costs $55 plus shipping within the USA.

There is also the Kryoflux which works a little differently. It's still an adapter but works at the lowest level of reading the magnetic flux from the disk, so it's agnostic of encoding scheme and spin speeds. It should therefore work with just about any format of disk. Software is included, and it's about 124 Euros.

If you want to try other ways... it's not particularly easy. What could be done is to find a 3.5" external floppy drive enclosure and use an adapter or modified cable similar to the one above on this page to convert its edge connector to a standard 34-pin 2-row header. The controller circuitry on the USB interface *may* support 5.25" drives (specifically 1.2 MB high-density ones), but it may not. Also, the HD (high-density) 5.25" drives run their motor at 360 rpm instead of the 300 rpm that all 3.5" drives spin at. SMSC made a USB bridge chip, USB97CFDC2-01. This supports "640K, 720K, 1.44M, 1.2M Windows 98 and 1.2M NEC DOS 6.x Formats" - you can possibly identify if your USB interface has this chip by checking in Device Manager. This chip has a VID of 0424 and a PID of 0fdc.

Power requirements are a little more tricky as many USB powered enclosures will not have enough power for a 5.25" drive. These usually have no more than +5V with a maximum current draw of 500mA. 5.25" floppy drives take power from a Molex 4-pin connector which provides +5V (red), GND (black), GND (black), and +12V (yellow). These drives do require both these voltage lines to function - the 12V line is used to power the stepper motor, and the 5V line is used for the logic board and read/write heads. So you'll need to get the +12V in there from a DC mains adapter.

Also be aware that PC floppy drives are jumpered as drive 1, not drive 0, so you will either have to find a cable with a twist, or determine how to re-jumper your drive.

Standard 5.25" floppy edge connector pinouts:

All pins on the other side are ground.