Information.
Release 13.06.1998

This is a first draft release of the BBC Disc Drive documentation.

The document as it exists at the moment is in a very early stage and there is still a fair amount of information and diagrams to be added.

I have decided to release it at this early stage due to a couple of reasons.

  1. Many people have been asking me for the results of a survey regarding disc drives that I did.
  2. It will help people sort out any problems they may be having connecting up drives.
  3. Others may have information that is missing in this document and therefore be able to notify me of gaps and help me fill them in.

The current version of this document will always be available from the BBC Documentation Project site http://members.magnet.at/marku/bbc.htm .

If you do have anything to add then please let me know.


Mark Usher
marku@magnet.at




1. Basic Computer Hardware


If you want to fit a disc drive to your BBC then the BBC must be fitted with a DFS (Disc Filing System). This basically consists of a floppy disc controller chip, some logic chips and a DFS ROM containing the software. These were supplied as kits for the BBC micro in two sorts, one based on the 8271 floppy disc controller (FDC) and the other was based on the 1770 (or sometimes even the 1772) chip. There were also available some kits that combined both of these controllers on one board for compatibility with protected software, even though the 1770 has an 8271 emulation.

You can check if your BBC has a DFS fitted or not by simply removing the cover and checking IC78 which is above and to the left of the keyboard connector. If it has a chip fitted then your BBC has an 8271 upgrade fitted, if there is a carrier board in this slot then you have a 1770 DFS upgrade fitted, and if it is empty then you will have to fit a DFS upgrade yourself.

The BBC B+ and Master series computers were fitted with a 1770 controller as standard (later models were fitted with the 1772), so you will not need to obtain anything for these computers.
Electron owners will need an extra interface that plugs onto the computer externally. The Acorn manufactured interface is called a Plus 3 and includes a built in 3.5" drive. There were also interfaces produced by other companies, some included drives and others you had to buy a drive separately and attach it to the interface yourself.

1.1. The 8271 DFS upgrade

The 8271 was the first upgrade to be introduced for the BBC. This is based on Intel's 8271 single density floppy disc controller which became rarer and rarer as the 80's progressed due to it being no longer manufactured. The 8271 chip is now very hard to find and, when it can be found is often sold at quite extortionate prices. The upgrade kit consisted of:

1 x 8271 Floppy Disc Controller for IC78
1 x 74LS123 for IC87 (Not required if Econet is already fitted).
1 x 74LS10 for IC82
1 x 74LS00 for IC77 (For a Model A without an analogue upgrade fitted).
2 x 7438 for IC's 79 & 80
2 x 74LS393 for ICs 81 & 86
2 x CD4013B for ICs 83 & 84
1 x CD4020B for IC85
1 x 8 way Dual In-Line (DIL) switch (optional – soldering necessary)
1 x Disc Filing System ROM (Acorn or otherwise) for IC88

Fitting.
  1. Insert all the IC's into the sockets provided on the main PCB.
  2. On issue 1 or 2 circuit boards only, connect the two pads of link position S8 with a wire link.
  3. On issue 1, 2 or 3 circuit boards only, cut the leg of IC27 pin 9 as close to the PCB as possible and the track connected to it on the component side of the circuit board between IC27 and IC89, then reconnect the cut IC leg to the East pad of link S9 with a short length of insulated wire.
  4. On issue 4 boards onwards, cut the TCW link at position S9.
  5. Set the following links using MOLEX jumpers:-
S18 – North
S19 – East
S20 – North
S21 – 2 x East/West
S22 – North
S32 – West
S33 – West
  1. Insert the 8 way DIL switch into the holes on the bottom right hand side of the keyboard and solder into place. Leave all the switches in the off position.

Technical description of the 8271 Disc Interface

IC78 is a floppy disc controller circuit which is used to interface to one or two, single or double sided 5 ¼ inch floppy disc drives. Logic signals from the controller to the disc drive are buffered by two open collector driver packages IC79 and 80. The incoming signal from the disc drive is first conditioned by monostable IC87 producing a pulse train with each pulse of fixed width. These pulses are then fed to the data seperation circuits ICs 81 and 82. These form a digital monostable. IC86 divides the 8MHz clock signal down to 31.25kHz. ICs 83, 84 and 85 are then used to detect index pulses coming in from the drive which show that the drive is ready for a read or write operation.

1.2. The 1770 DFS upgrade

The 1770/1772 was manufactured by Western Digital and is a more modern double density controller, allowing an extra 80% storage capacity on a floppy disc. It is though a different physical size to the 8271 controller and consequently it has to be mounted on a small carrier board before it can be fitted into the IC78 slot on the BBC. This means that unless you have an original upgrade kit or a circuit design for a carrier board, that it would not be possible to fit this upgrade. I would like to publish a carrier board design, but at the moment I do not have one.

Before Acorn released their 1770 Upgrade kit, there were many others on the market, most notably from Solidisk and Watford Electronics. The 1770 upgrade also enables the BBC to use Acorn's ADFS – Advanced Disc Filing System with floppies which isn't possible with the 8271, although caution must be used here as the ADFS was released after many of these upgrade boards became available. Hence, with some 1770 upgrades there is an incompatibility with Acorn's ADFS, most notably the Solidisk board. Most of the incompatible boards did have a revision released after the issue of ADFS to overcome this problem. e.g. Solidisk Issue II is compatible with Acorn's ADFS.

Fitting instructions for Acorn's 1770 DFS Upgrade are available in a separate document at http://www.nvg.unit.no/bbc/doc/1770FittingInstructions.zip
Another point is Acorn's upgrade did not make use of the double density feature available with the 1770 FDC, whereas most of the other upgrades did.

1.3. Other upgrades

There were numerous other upgrades available.

Solidisk released the DFDC (Dual Floppy Disc Controllers) interface board. This was basically a carrier board with both 1770 and 8271 FDC's thus giving full compatibility. You changed between the two by the use of a small switch.

OPUS released their DDOS system which is again on a carrier board. I know little about this upgrade though. They also had some combined RAM disc and floppy drive systems that plugged directly into the 1MHz bus connector.

Matt Callow [callow@gfms.bt.co.uk] mentioned that he has a 1797 floppy controller mounted on a separate board (made by Computer Village Ltd.). At boot up the BBC reports 'LVL Dos'. I have no other information about this upgrade.

Kenda DMFS.
No information. Was this a 1771 based DFS ?

2. The DFS's

2.1. Acorn

DFS-0.9
8271 BBC B
DFS-0.98
8271 BBC B
DNFS 1.2
8271 BBC B
DFS 2.0j
1770 BBC B/B+
This was the first release of the 1770 DFS and was in EPROM.
DFS 2.10
1770 BBC B/B+
The same as v2.0j but in ROM.
DFS 2.20
1770 BBC B/B+
The release of the BBC B+ 128 saw version 2.2 DFS released. This was also used in the Master 128.
Shift-Z Break function included to emulate the 8271.
Extra commands necessary to deal with the 64K of paged RAM in the B+.
DFS 2.21
No record of it's release or existence.
DFS 2.22
1770 BBC B/B+
Developed to fix an esoteric OSFILE bug.
Also the 128k associated SRAM utilities have been tidied up to make them more user friendly.
This version will not work in all BBC Model B's fitted with a 1770 upgrade board.
DFS 2.23
1770 BBC B/B+
Cures the problem of v2.22 not working in all BBC's.
DFS 2.24
Master MOS 3.20
Loading with OSFILE &FF returns A=1.
File saves>64K work
DFS 2.25
1770 BBC B/B+
CLOSE#0 and *CLOSE and *SHUT leaves files with correct length.
Writing to extent works correctly.
Unknown command as LIBFS works correctly
DFS 2.26
1770 BBC B/B+
Last for the B/B+
OSGBPB speeded-up.
All four head step rates implemented i.e.
*CONFIGURE FDRIVE 0 1 2 3
for 1770 6 12 20 30 mS
for 1772 6 12 2 3 mS
DFS 2.27/8
Master
Software patch for spurious Motor-on after 1770 reset.
Following fixed:
If a) A file was open
b) the disk had been changed
c) BREAK was pressed
then the old disk catalogue would be written to the new disk.
DFS 2.29
OSGBPB tube problem introduced at 2.26 fixed.
*CONFIGURE FDRIVE 2 has software delay added to hardware delay.
This allows for support of slow step rate drives with 1772 fitted, i.e.
*CONFIGURE FDRIVE 0 1 2 3
for 1770 6 12 50 30 mS
for 1772 6 12 32 3 mS
DFS 2.45
Master MOS 3.50
You can now save files longer than 64k bytes.
All four step rates are now used.
OSGBPB now executes more quickly.
CLOSE#0 leaves files with the correct length.

2.2. Amcom DFS

When running an AMCOM DFS from sideways RAM you must write protect the sideways RAM bank as the DFS has a copy protection. The major incompatibility with this DFS is that you can't use coloured titles on a disc as the DFS uses an upper bit in the title string to signify extended mode so anything out of the ordinary in a disc tittle will confuse it.

2.3. HDFS

Angus Duggans DFS. For a full description of this DFS see http://www.nvg.unit.no/bbc/doc/HDFS.ps This is in PostScript format.

2.4. MRM E00 DFS.

This was a basic 8271 upgrade except that the DFS ROM was on a carrier board with it's own RAM chips. The RAM supplied on board serves as a dedicated disc workspace freeing existing RAM from &E00 to &1900. This will also run from sideways RAM as long as the sideways RAM bank is not write protected. There are some limitations to this DFS though. First, command lines in BUILD files should be less than 100 characters in length. Second, the maximum number of files which you may access at any one time is four (the standard allows five).

2.5. Watford

2.6. Solidisk

2.7. UDM United Disk Memories

3. The Drives

3.1. Drives in general

The BBC had many assorted drives attached to it, ranging from 8", 5¼", 3½" and 3" drives. The most widely used was the 5¼" drive and later with the Electron Plus 3 and the Master series the 3½ drive became the standard used.

Disk drives were sold by many different companies for the BBC, including Watford, Viglin and Cumana amongst others. Most of these drives though were badged drives from Japanese manufacturers, the most common being Epson, Mitsubishi and TEAC. There were two normal standards for the 5¼" disk drive, 40 and 80 track. The 40 track drive lays down it's magnetic tracks at a pitch of 48 tracks per inch (48 TPI) whilst the 80 track drives operate at 96 TPI, i.e. exactly half the track width of the 40 track drive. Both 40 and 80 track drives were available with a single head (which records on one side of the disk only) or with a double head enabling recording on both sides. A double headed drive has therefore twice the storage capacity of a single headed drive.

Using 8271 based DFS (FM encoding) disk capacities are:
BBC Formatted
Unformatted
40 Track Single Sided
100KB
250KB
40 Track Double Sided
200KB
500KB
80 Track Single Sided
200KB
500KB
80 Track Double Sided
400KB
1MB

Using 1770 based DFS (MFM encoding) disk capacities are:
BBC Formatted
Unformatted
40 Track Single Sided
180KB
250KB
40 Track Double Sided
360KB
500KB
80 Track Single Sided
360KB
500KB
80 Track Double Sided
720KB
1MB

3.2. Finding a suitable drive

Obviously the best drive for the BBC is an 80 Track double sided drive as this would give us the full 400K. Unfortunately these drives are not so common as 5¼" 720K drives were never used in PC's. Also 80 track single sided drives are quite uncommon, again for the same reasons. A 40 track double sided drive should be quite easy to find as they were used extensively in older PC's, but then we only have half the storage capacity that is possible. There were on the other hand many 720KB 3.5" disc drives made, as these were used by various computer manufacturers, so if you want to use 3.5" discs then these should be a lot easier to find. An added advantage is also that 3.5" double density discs are also easier to find than 5¼" double density discs, but for how long is another question entirely.

Many high density PC floppy drives i.e. 3.5" 1.44MB drives and 5¼" 1.2MB drives can also run in low density modes. Most of the 3.5" drives will switch between the two formats automatically, whereas the 5¼" drives are normally set as 1.2MB drives at the factory and need some jumpers changing before they will operate in a dual mode. The jumpers that need setting are labelled differently on different models, but you should look for High/Low density, and the rotation speed jumper. This is set to 360 RPM for high density operation, and so must be changed to dual 300/360 RPM mode so that low density can also be used.

As far as my test show, these drives will work with a 1770/1772 FDC but cause problems with the 8271 FDC. The reason seems to lie with the 8271 DFS and the timings contained within the DFS code. Jonathan Harston has written a program that will patch an Acorn DNFS 1.20 ROM image to change the DFS timings, and my tests show that this does indeed solve the problems. You must also remember to set the timings on the BBC keyboard links. The program has been included in the archive that contains this document. Just transfer the program to a disc that also contains an image of the Acorn DNFS 1.20 ROM. Run the program, you will be asked a few questions to which you answer yes or no, and then you will be the program will print the *SAVE command that you must use to save the new image. The program does not save the new image automatically.

3.3. Attaching Drives

First you will need a power supply. You can use the power supply from the underside of the BBC with a suitable lead. If you don't have a lead then this can be a problem as it is very hard to find the connector. The exact details are:

PSU socket: AMP 1-350241
PSU female pins: AMP 360666-1
cable connector: AMP 1-250234
male pins: AMP 350664-1

Alternatively you can use a power supply from a PC.
Besides a power supply you will also need a data transfer cable. This is a simple 34way ribbon cable, with an edge connector for the drive and another connector for the underside of the BBC. Be careful if you are using a PC floppy drive cable as this contains a twist in the cable. This is because all PC floppy drives are set as drive 1, and the twist reverses this for the first drive, effectively making it drive 0. The BBC doesn't operate like this. So if you are wanting to connect two drives you will have to "remove" the twist, or in a single drive system, just use the connector before the twist.

Once you have your BBC, DFS, drive and cables, you must configure the drive before connecting it up. If it is an old PC drive then it will be jumpered as DS1 (Drive 1) by default. If it is to be Drive 0 on your BBC, you must change the jumper to DS0, and in a dual drive system you would change the jumper on only one of the drives, so one is DS0 and the second is DS1.

Also the last drive on the cable, i.e. the one furthest away from the BBC must be terminated. Drives are also terminated by default. This is fine if you have a single drive system, but in a dual drive system the terminator must be removed on the drive nearest the BBC on the cable.

Terminators vary between drives. Some look like an IC and are usually in a DIL socket, or sometimes they are a thin row that is attached to the drives circuit board. Another possibility is that the terminator can be turned on or off by use of a DIL switch or jumper on the drives circuit board e.g. some Mitsubishi drives.

Once you have set all of this, you can then attach your drive and BBC together and start trying to format some disks.

3.4. Other drive jumpers


Head Loading

Some drives use a head load solenoid. This means that it requires either a Motor On or a valid Drive select signal before the head can be loaded against the media for communication with the disk. This is the purpose of the two, switch or link options found on many drives, HM or HS. These stand for Head to Motor and Head to Drive Select respectively. This means with the HM link set, the head of the disk drive will be loaded against the disk any time the motor is started up. It may well be that the computer wishes to access another drive, but as all the Motor On lines are usually connected together the motors of all the drives will be activated. Thus, any drive that has the HM option set will load the head of the drive against the media. When the computer comes to use that drive, then the drive will already be in a condition to pass information to and from the disk.

Head to Select

With the switch or link set in the HS position then the loading of the head against the media will only take place when that particular drive is actually selected for communication between its disk media and the computer. That is to say that with the HS option selected and a drive set to be drive one or DS1 of the system, then only when drive one is selected will the head of the drive actually be loaded ready for use.

For and against

There are arguments for and against both methods of head selection. With the HM option there is more wear on the disk due to the head always being loaded when any drive is selected or used. Any drive access however small will result in all the heads of all the drives being loaded against the media. If you have the HM option selected you will not require a Head Settling time before the drive is Ready For Use. It speeds up drive to drive access time and is a lot quieter if a lot of drive to drive transfers are taking place.
In the case of the HS option then disk wear is reduced to a minimum as the head is only in contact with the media when an access is required to that particular drive. This results in a lot of clicking taking place during drive to drive transfers. It also means that when the drive is selected then a small amount of time must be allowed for the head to settle against the disk before access is attempted. This is known as Head Settling time and can be as much as 50 m/s in older drives.

Self Loading

It may be that you have a drive that contains neither the HS or HM link options. If this is the case the drive is most likely to be the type whereby the head is loaded against the disk every time the drive door is closed. This means that the head of the drive is in contact with the disk at all times. This results in an even higher degree of disk wear than a drive with the HM option set.

Multiplexing

Another connection that can be found on floppy drives is the MX link. This is one that often causes trouble and confusion. Its purpose is to allow two or more drives to be connected together on the same cable. Incorrect setting of this can cause surprising results, even causing you to think there is a fault with another drive on the system.
The MX link should not be set in most drives, however in some of the early TEAC drives the opposite is true. It is also quite normal for the MX link not to be made in single drive systems.

3.5 BBC keyboard link configurations

Here are tables detailing the various link settings on the lower right hand side of the keyboard.

First all the settings:

BIT
Switch
Setting
Description




0
8
Start up Mode
1
7

2
6

3
5
0
!BOOT on Shift Break


1
!BOOT on Break
4
4
Disk Stepping times
5
3

6
2
0
HADFS Floppy driver


1
external driver
7
1
0
DNFS. Starts in DFS


1
DNFS. Starts in NFS

Here are the settings for the 8271 controller.

SW3
SW4
Step rate
Settle time
Head load
1
1
4ms
16ms
0ms
1
0
6ms
16ms
0ms
0
1
6ms
50ms
8ms
0
0
20ms
20ms
16ms

NB: Some documents state the last two times for head load are 32 and 64, not 8 and 16.

Here are the settings for the 1770 controller (up to DFS v2.29)

SW3
SW4
Step rate
Settle time
Head load
1
1
6ms

1
0
12ms

0
1
20ms

0
0
30ms


Here are the settings for the 1772 controller (up to DFS v2.29)

SW3
SW4
Step rate
Settle time
Head load
1
1
6ms

1
0
12ms

0
1
2ms

0
0
3ms


Setting link 3 and not link 4 will give you the slowest step time possible
with the 1772. You should avoid setting the step time of a standard 5.25
inch disc drive to 2 or 3ms with the 1772 chip, as most drives will not work
at these speeds.

4. Appendix 1

Disc Drive Chart

This chart should help you find a drive to use with the BBC. 1.2MB and 1.44MB models have not been included. The In use column signifies if a particular drive is known to be used with a BBC

Size
Unformatted capacity
Formatted capacity
Density
Manufacturer
Model
Height
In use
5¼"
250KB
180KB
SSDD
BASF
6106
Full
No
5¼"
250KB
180KB
SSDD
CDC
9408
Full
No
5¼"
250KB
180KB
SSDD
CDC
9428-1
Half
No
5¼"
250KB
180KB
SSDD
Hi-Tech
548-25
Half
No
5¼"
250KB
180KB
SSDD
M.P.I.
501
Half
No
5¼"
250KB
180KB
SSDD
M.P.I.
51M
Full
No
5¼"
250KB
180KB
SSDD
M.P.I.
B51S
Full
No
5¼"
250KB
180KB
SSDD
Pertec
FD200
Full
No
5¼"
250KB
180KB
SSDD
Shugart
SA200
Half
No
5¼"
250KB
180KB
SSDD
Shugart
SA215
Half
No
5¼"
250KB
180KB
SSDD
Shugart
SA390
Full
No
5¼"
250KB
180KB
SSDD
Shugart
SA400
Full
No
5¼"
250KB
180KB
SSDD
Tandon
TM100-1A
Full
No
5¼"
250KB
180KB
SSDD
Tandon
TM50-1
Half
No
5¼"
250KB
180KB
SSDD
Tandon
TM55-1
Half
No
5¼"
250KB
180KB
SSDD
Tandon
TM65-1L
Half
No
5¼"
250KB
180KB
SSDD
Teac
50A
Full
No
5¼"
250KB
180KB
SSDD
Teac
55A
Half
Yes
5¼"
250KB
180KB
SSDD
Tec
FB501
Half
Yes
5¼"
250KB
180KB
SSDD
Texas Peripherals
10-5355-001
Full
No
5¼"
250KB
180KB
SSDD
World Storage
FD100-5
Full
No
5¼"
250KB
180KB
SSSD
Alps
FDD 2124
Half
No
5¼"
250KB
180KB
SSSD
Shugart
SA400L
Full
No
5¼"
250KB
180KB
SSSD
Siemens
FDD100-5
Full
No
5¼"
250KB
180KB
MPI
51-S
Full
No
5¼"
500KB
360KB
Teac
55E
Half
No
5¼"
500KB
360KB
DSQD
Weltec
M48D-1
Half
No
5¼"
500KB
360KB
DSDD
Alps
2624-BKI
Half
No
5¼"
500KB
360KB
DSDD
Alps
DFC 222 AO5A
Half
No
5¼"
500KB
360KB
DSDD
Alps
DFC 222 BO2A
Half
No
5¼"
500KB
360KB
DSDD
Alps
FDD 2124A
Full
No
5¼"
500KB
360KB
DSDD
Bachelor
FD-104
Half
No
5¼"
500KB
360KB
DSDD
BASF
6128
Half
No
5¼"
500KB
360KB
DSDD
Canon
5201
Half
No
5¼"
500KB
360KB
DSDD
Canon
531
Half
No
5¼"
500KB
360KB
DSDD
CDC
9409
Full
No
5¼"
500KB
360KB
DSDD
CDC
9428
Half
No
5¼"
500KB
360KB
DSDD
CDC
9428-2
Half
No
5¼"
500KB
360KB
DSDD
Chinon
502
Half
Yes
5¼"
500KB
360KB
DSDD
Epson
500
Half
No
5¼"
500KB
360KB
DSDD
Epson
521L
Half
No
5¼"
500KB
360KB
DSDD
Epson
SD-521
Half
No
5¼"
500KB
360KB
DSDD
Epson
SD-621L-xxx
Half
No
5¼"
500KB
360KB
DSDD
Epson
SD321
1/3
No
5¼"
500KB
360KB
DSDD
Fujitsu
2551K
Half
No
5¼"
500KB
360KB
DSDD
Hewlett Packard
J455-3
Half
No
5¼"
500KB
360KB
DSDD
Hi-Tech
548-50
Half
No
5¼"
500KB
360KB
DSDD
Hi-Tech
548-A
Half
No
5¼"
500KB
360KB
DSDD
I.B.M.
0384-002
Full
No
5¼"
500KB
360KB
DSDD
M.P.I.
502B
Half
No
5¼"
500KB
360KB
DSDD
M.P.I.
52M
Full
No
5¼"
500KB
360KB
DSDD
M.P.I.
52S
Full
No
5¼"
500KB
360KB
DSDD
M.P.I.
B52S
Full
No
5¼"
500KB
360KB
DSDD
Maple Tech
MT-502
Half
No
5¼"
500KB
360KB
DSDD
Micropolis
1016-2
Full
No
5¼"
500KB
360KB
DSDD
Mitac
MC-490
Half
No
5¼"
500KB
360KB
DSDD
Mitsubishi
4851
Half
Yes
5¼"
500KB
360KB
DSDD
Mitsubishi
501A
Half
No
5¼"
500KB
360KB
DSDD
Mitsubishi
501B
Half
No
5¼"
500KB
360KB
DSDD
Mitsubishi
501C
Half
No
5¼"
500KB
360KB
DSDD
Mitsumi
D503
Half
No
5¼"
500KB
360KB
DSDD
N.E.C
1053
Half
No
5¼"
500KB
360KB
DSDD
Okidata
3305
Half
No
5¼"
500KB
360KB
DSDD
Okidata
3305BU
1/3
No
5¼"
500KB
360KB
DSDD
Okidata
3305U
Half
No
5¼"
500KB
360KB
DSDD
Okidata
3315B
Half
No
5¼"
500KB
360KB
DSDD
Olivetti
4311-3
Half
No
5¼"
500KB
360KB
DSDD
Olivetti
XM4311
Half
No
5¼"
500KB
360KB
DSDD
Panasonic
455
Half
No
5¼"
500KB
360KB
DSDD
Panasonic
551
Half
No
5¼"
500KB
360KB
DSDD
Pertec
FD250
Full
No
5¼"
500KB
360KB
DSDD
Phillips
3132
Half
No
5¼"
500KB
360KB
DSDD
Qume
142
Half
No
5¼"
500KB
360KB
DSDD
Qume
542
Full
No
5¼"
500KB
360KB
DSDD
Qume
DT/5
Full
No
5¼"
500KB
360KB
DSDD
Remex
RFD 480
Half
No
5¼"
500KB
360KB
DSDD
Samsung
SFD500K
Half
No
5¼"
500KB
360KB
DSDD
Sanyo
500C
Half
No
5¼"
500KB
360KB
DSDD
Sanyo
FDA-5200
Half
No
5¼"
500KB
360KB
DSDD
Shugart
SA210
Half
No
5¼"
500KB
360KB
DSDD
Shugart
SA450
Full
No
5¼"
500KB
360KB
DSDD
Shugart
SA455
Half
No
5¼"
500KB
360KB
DSDD
Shugart
SA551
Half
No
5¼"
500KB
360KB
DSDD
Siemens
FDD221-5
Full
No
5¼"
500KB
360KB
DSDD
Tandon
TM100-2A
Full
No
5¼"
500KB
360KB
DSDD
Tandon
TM101-2
Full
No
5¼"
500KB
360KB
DSDD
Tandon
TM50-2
Half
No
5¼"
500KB
360KB
DSDD
Tandon
TM55-2
Half
No
5¼"
500KB
360KB
DSDD
Tandon
TM65-2L
Half
No
5¼"
500KB
360KB
DSDD
Tandon
TM75-2
Half
No
5¼"
500KB
360KB
DSDD
Teac
53B
Half
No
5¼"
500KB
360KB
DSDD
Teac
55B
Half
No
5¼"
500KB
360KB
DSDD
Teac
55BR
Half
No
5¼"
500KB
360KB
DSDD
Teac
55BV
Half
No
5¼"
500KB
360KB
DSDD
Tec
FB503
Half
No
5¼"
500KB
360KB
DSDD
Toshiba
0242A
Half
No
5¼"
500KB
360KB
DSDD
Toshiba
5401
Half
No
5¼"
500KB
360KB
DSDD
Toshiba
5406
Half
No
5¼"
500KB
360KB
DSDD
Toshiba
5426
Half
No
5¼"
500KB
360KB
DSDD
Toshiba
5451
Half
No
5¼"
500KB
360KB
DSDD
Toshiba
5454
Half
No
5¼"
500KB
360KB
DSDD
Toshiba
5471
Half
No
5¼"
500KB
360KB
DSDD
Toshiba
5472
Half
No
5¼"
500KB
360KB
DSDD
Toshiba
5474
Half
No
5¼"
500KB
360KB
DSDD
Toshiba
6371
Half
No
5¼"
500KB
360KB
DSDD
Toshiba
6374
Half
No
5¼"
500KB
360KB
DSDD
Toshiba
6471
Half
No
5¼"
500KB
360KB
DSDD
Toshiba
6474-T2P
Half
No
5¼"
500KB
360KB
DSDD
Toshiba
M48D-12
Half
No
5¼"
500KB
360KB
DSDD
Weltec
M48D-14
Half
No
5¼"
500KB
360KB
DSDD
World Storage
FD200-5
Full
No
5¼"
500KB
360KB
DSDD
YE Data
YD580
Half
No
5¼"
500KB
360KB
DSDD
YE Data
YD580B
Half
No
5¼"
500KB
360KB
SSQD
CDC
9429-1
Half
No
5¼"
500KB
360KB
SSQD
M.P.I.
91M
Full
No
5¼"
500KB
360KB
SSQD
M.P.I.
B101M-S
Full
No
5¼"
500KB
360KB
SSQD
M.P.I.
B91S
Full
No
5¼"
500KB
360KB
SSQD
Tandon
TM100-3
Full
No
5¼"
500KB
360KB
SSQD
Tandon
TM100-3M
Full
No
5¼"
500KB
360KB
SSQD
Tandon
TM101-3
Full
No
5¼"
500KB
360KB
SSQD
Victor
TM100-3-VIC
Full
No
5¼"
500KB
360KB
SSDD
Hitachi
HFD 305S
Half
No
5¼"
500KB
360KB
SSDD
Micropolis
1015-2
Full
No
5¼"
500KB
360KB
SSDD
Micropolis
1115-5
Full
No
5¼"
500KB
360KB
SSDD
Phillips
3121
Half
No
5¼"
500KB
360KB
SSDD
Shugart
SA300
Half
No
5¼"
500KB
360KB
SSDD
Shugart
SA410
Full
Yes
5¼"
500KB
360KB
SSDD
Siemens
FDD121-5
Full
No
5¼"
500KB
360KB
SSDD
Siemens
FDD196-5
Full
No
5¼"
500KB
360KB
Epson
SD-520
Half
No
5¼"
500KB
360KB
Micro Solutions
BACKPACK(5L)
Half
No
5¼"
500KB
360KB
Mitsubishi
4852
Full
No
5¼"
500KB
360KB
Mitsubishi
MF501A,B
Half
No
5¼"
500KB
360KB
MPI
52-S
Full
No
5¼"
500KB
360KB
PACIFIC RIM
U360
Half
No
5¼"
500KB
360KB
SHUGART
SA460
Full
No
5¼"
500KB
360KB
Toshiba
0401GR
Half
No
5¼"
1.0MB
720KB
DSQD
AT&T
KS-23114
Half
No
5¼"
1.0MB
720KB
DSQD
BASF
6138
Half
No
5¼"
1.0MB
720KB
DSQD
Canon
220
Half
Yes
5¼"
1.0MB
720KB
DSQD
Canon
221
Yes
5¼"
1.0MB
720KB
DSQD
Canon
530
Half
No
5¼"
1.0MB
720KB
DSQD
CDC
9409T
Full
No
5¼"
1.0MB
720KB
DSQD
CDC
9429
Half
No
5¼"
1.0MB
720KB
DSQD
Fujitsu
2554K
Half
No
5¼"
1.0MB
720KB
DSQD
Fujitsu
M2552A
Half
No
5¼"
1.0MB
720KB
DSQD
Hi-Tech
596-10
Full
No
5¼"
1.0MB
720KB
DSQD
JVC
MDP-100
Half
Yes
5¼"
1.0MB
720KB
DSQD
M.P.I.
92M-002
Full
No
5¼"
1.0MB
720KB
DSQD
M.P.I.
B102M-S
Full
No
5¼"
1.0MB
720KB
DSQD
M.P.I.
B92M
Full
No
5¼"
1.0MB
720KB
DSQD
M.P.I.
B92S
Full
No
5¼"
1.0MB
720KB
DSQD
Micropolis
1006-4N
Full
No
5¼"
1.0MB
720KB
DSQD
Micropolis
1015-4
Full
No
5¼"
1.0MB
720KB
DSQD
Micropolis
1015-6
Full
No
5¼"
1.0MB
720KB
DSQD
Micropolis
1115-4
Full
No
5¼"
1.0MB
720KB
DSQD
Micropolis
1115-6
Full
No
5¼"
1.0MB
720KB
DSQD
Micropolis
1117-6
Full
No
5¼"
1.0MB
720KB
DSQD
Mitsubishi
4852
Half
No
5¼"
1.0MB
720KB
DSQD
Mitsubishi
4853
Half
Yes
5¼"
1.0MB
720KB
DSQD
Mitsubishi
4853
Half
No
5¼"
1.0MB
720KB
DSQD
Mitsubishi
503
Half
Yes
5¼"
1.0MB
720KB
DSQD
N.E.C
1055
Half
Yes
5¼"
1.0MB
720KB
DSQD
Panasonic
465
Half
No
5¼"
1.0MB
720KB
DSQD
Panasonic
595
Half
No
5¼"
1.0MB
720KB
DSQD
Ricoh
5100
Half
No
5¼"
1.0MB
720KB
DSQD
Seiko
8640
Full
No
5¼"
1.0MB
720KB
DSQD
Shugart
SA460
Full
No
5¼"
1.0MB
720KB
DSQD
Shugart
SA465
Half
Yes
5¼"
1.0MB
720KB
DSQD
Shugart
SA561
Half
No
5¼"
1.0MB
720KB
DSQD
Tandon
TM100-4
Full
No
5¼"
1.0MB
720KB
DSQD
Tandon
TM100-4A
Full
No
5¼"
1.0MB
720KB
DSQD
Tandon
TM101-4
Full
No
5¼"
1.0MB
720KB
DSQD
Tandon
TM101-4A
Full
No
5¼"
1.0MB
720KB
DSQD
Tandon
TM55-4
Half
No
5¼"
1.0MB
720KB
DSQD
Tandon
TM65-4
Half
No
5¼"
1.0MB
720KB
DSQD
Teac
55FR
Half
Yes
5¼"
1.0MB
720KB
DSQD
Teac
55FV
Half
No
5¼"
1.0MB
720KB
DSQD
Tec
FB504
Half
No
5¼"
1.0MB
720KB
DSQD
Toshiba
0202A
Full
No
5¼"
1.0MB
720KB
DSQD
Toshiba
5629
Half
No
5¼"
1.0MB
720KB
DSQD
Victor
TM100-4-VIC
Full
No
5¼"
1.0MB
720KB
DSQD
Weltec
M16-P12
Half
No
5¼"
1.0MB
720KB
DSQD
Weltec
N96-12
Half
No
5¼"
1.0MB
720KB
DSQD
YE Data
YD280
Full
No
5¼"
1.0MB
720KB
DSDD
Phillips
3133
Half
No
5¼"
1.0MB
720KB
DSDD
Weltec
M16-R12/910
Half
No
3½"
1.0MB
720KB
DSQD
Chinon
FB354
Half
Yes
3½"
1.0MB
720KB
DSQD
Citizen
OPDB-22A
1/3
No
3½"
1.0MB
720KB
DSQD
Citizen
OSDA-01D
1/3
No
3½"
1.0MB
720KB
DSQD
Citizen
OSDA-77D
1/3
No
3½"
1.0MB
720KB
DSQD
Citizen
OSDA-90E-U
1/3
No
3½"
1.0MB
720KB
DSQD
Citizen
OSDD-05B
1/3
No
3½"
1.0MB
720KB
DSQD
Citizen
OSDD-57
1/3
No
3½"
1.0MB
720KB
DSQD
Citizen
OSDD-57B
1/3
No
3½"
1.0MB
720KB
DSQD
Epson
180
Half
No
3½"
1.0MB
720KB
DSQD
Epson
200P-053
Half
No
3½"
1.0MB
720KB
DSQD
Epson
200P-055
Half
No
3½"
1.0MB
720KB
DSQD
Epson
200P-073
Half
No
3½"
1.0MB
720KB
DSQD
Epson
280
1/3
No
3½"
1.0MB
720KB
DSQD
Epson
SMD-380-xxx
1/3
No
3½"
1.0MB
720KB
DSQD
Epson
SMD-389-xxx
Half
No
3½"
1.0MB
720KB
DSQD
Fujitsu
M2551A
No
3½"
1.0MB
720KB
DSQD
Fujitsu
N02B-0112-B001
Half
No
3½"
1.0MB
720KB
DSQD
Fujitsu
N02B-0112-B201
Half
No
3½"
1.0MB
720KB
DSQD
Mitsubishi
353-12
1/3
No
3½"
1.0MB
720KB
DSQD
Mitsubishi
353AF
Half
Yes
3½"
1.0MB
720KB
DSQD
Mitsubishi
353B-12
Half
No
3½"
1.0MB
720KB
DSQD
Mitsubishi
353B-82
1/3
No
3½"
1.0MB
720KB
DSQD
Mitsubishi
353C
1/3
No
3½"
1.0MB
720KB
DSQD
Mitsubishi
MF353B,C
Half
No
3½"
1.0MB
720KB
DSQD
Mitsumi

No
3½"
1.0MB
720KB
DSQD
N.E.C
1035
Half
No
3½"
1.0MB
720KB
DSQD
N.E.C
1036A
1/3
No
3½"
1.0MB
720KB
DSQD
N.E.C
1037A
1/3
No
3½"
1.0MB
720KB
DSQD
Newtronic
D357
1/3
No
3½"
1.0MB
720KB
DSQD
PACIFIC RIM
U720
No
3½"
1.0MB
720KB
DSQD
Panasonic
253
1/3
Yes
3½"
1.0MB
720KB
DSQD
Sony
53W
1/3
No
3½"
1.0MB
720KB
DSQD
Sony
63W
1/3
Yes
3½"
1.0MB
720KB
DSQD
Sony
MP-F11W
1/3
No
3½"
1.0MB
720KB
DSQD
Teac
135FN
1/3
No
3½"
1.0MB
720KB
DSQD
Teac
235F
1/3
No
3½"
1.0MB
720KB
DSQD
Teac
335F
19.0
No
3½"
1.0MB
720KB
DSQD
Teac
35F
Half
No
3½"
1.0MB
720KB
DSQD
Teac
35FN
Half
No
3½"
1.0MB
720KB
DSQD
Toshiba
3527H
1/3
No
3½"
1.0MB
720KB
DSQD
Toshiba
3527TH
1/3
No
3½"
1.0MB
720KB
DSQD
Toshiba
352TH
1/3
No
3½"
1.0MB
720KB
DSQD
Toshiba
4202-AOK
1/3
No
3½"
1.0MB
720KB
DSQD
Toshiba
4207-AOK
1/3
No
3½"
1.0MB
720KB
DSQD
Toshiba
4207-AOK
1"
No
3½"
1.0MB
720KB
DSQD
Toshiba
4210
1/3
No
3½"
1.0MB
720KB
DSQD
Toshiba
4261
1/3
No
3½"
1.0MB
720KB
DSQD
Toshiba
ND-352T,S
1/3
No
3½"
1.0MB
720KB
DSQD
Toshiba
ND-354A
1/3
No


5. Appendix 2


Floppy Disc Controller Technical Information


1771 Pin information
1
VBB
-5V
2
!WE
!Write enable
A logic low copies the data on the DAL into the selected register when CS is low.
3
!CS
!Chip select
4
!RE
!Read enable
A logic low on this input controls the placement of data from a selected register on the DAL when !CS is low.
5,6
A0-A1
Register select:


A1
A0
!RE
!WE
0
0
Status register
Command register
0
1
Track register
Track register
1
0
Sector register
Sector register
1
1
Data register
Data register
7-14
!DAL0-DAL7
!Data Access Lines
Enabled by !RE OR !WE
15
!PH1/STEP
!Phase 1/Step
If the !3PM input is low then three phase motor control is selected and !PH1-PH3 outputs are used to control it.
16
!PH2/DIRC
!Phase 2/Dir
17
PH3
!Phase 3
18
!3PM
!3 phase motor select
19
!MR
???
!PH1 is active low after !MR.
20
VSS
GND
21
VC
+5V
22
!TEST
!Test
Should be tied to +5V or left floating.
23
HLT
Head load timing
When this is logic 1, the head is assumed to be engaged.
24
CLK
Clock
Free running 2MHz +-1% square wave for internal uses.
25
!XTDS
!External data
Logic low or open selects seperation
the internal data separator
26
FDCLOCK
Floppy disc clock
For external data separation
27
FDDATA
Floppy disc data
Raw data if !XTDS is 1 or externally separated data if !XTDS is 0.
28
HLD
Head load
Controls the loading of the RW head against the media.
29
TG43
Track greater than 43
30
WG

31
WD
Contains clock and data bits
32
READY
Ready
Same is !b7 in the status register
33
!WF
Write fault
34
!TR00
!Track 00
35
!IP
!Index pulse
Held for a minimum of 10us when an index mark is found on the disc.
36
!WPRT
!Write protect
A logic low terminates a command and sets the write protect bit.
37
!DINT
!Disc initialisation
If !DINT=0 the operation is cancelled and the write protect bit is set.
38
DRQ
!Data request
Indicates that more data is needed in the data register, or the data is waiting to be taken.
39
INTRQ
Interrupt request
Set at the completion (successful or otherwise) of any operation. Use a 10k pull resistor to +5V.
40
VDD
+12V