Floppy drives

Floppy drives in microcomputers' time were a sign of luxury - they were very expensive, sometimes more expensive than a computer itself, and usually were very slow. In some appliances they were required, but it was usually done in big databases, accounting software or industrial data collecting. In home computers they weren't popular.

Because 8-bit microcomputers are simple, they usually don't have floppy drive controller. So the floppy drive unit had to be nearly a complete computer which communicated with micro using bus and had its own operating system called DOS (Disk Operating System).


Atari 1050
Atari 8-bit computers (XL/XE series)
Manufactured by: Atari

Format: 5.25", 88/127K (single/dual density)
Conected to: Atari SIO (serial port)
Capabilities:
 - Atari 810 compatible
 - 6507 microprocessor based controller built-in
 - 19200bps transfer
 - New version of Atari DOS, not 100% compatible with 810's.

 


 

Atari 1050 was a typical floppy drive used with Atari 800XL microcomputer. As 810 drive could use only 88K of the disk, 1050 could use double density - 127K. Unfortunately it's Atari DOS 3.0 was not completely compatible with 810's DOS making many programs unusable.

My unit comes from my university. I spotted it thrown to recycling and I bought it (with tape recorder and Atari 800XL) cheap. Unfortunately, it seems to be damaged seriously, it's not starting. As I removed all damaged chips, not many left in there.

WARNING! If you unplug data cable, be sure to unplug power supply cable first! If not, U1 may be damaged!

Power Supply:

1-2  -  9V AC at 3.0A
(without load power supply may get higher voltage - it's normal)

DO NOT PLUG DC! It'll DESTROY Graetz rectifier diodes!

 

Indus GT
Atari 8-bit computers (XL/XE series)
Manufactured by: Indus

Format: 5.25" Double density (179K?)
Connected to: Atari SIO (serial port)
Capabilities:
 - High capacity of disks
 - Higher speed
 - Control panel with 7-segment display and buttons for showing drive state info
 - Possible to boot CP/M using drive's integrated Z80 CPU, but only when RAMCharger card is installed to give 64K of RAM to FDD.
 - Office software included on floppy disks
This drive is a Ferrari among drives. It's faster, can write bigger disks and can even boot CP/M in Atari. How? The drive uses Z80 CPU, so CP/M can run on it making Atari terminal only. But to make CP/M running you need to have RAMCharger expansion installed in Indus GT drive, giving it 64K of RAM. It's hard to get this expansion, see links to get information how to build it.

My unit seems to work (initializes properly, boots software and reacts to commands), but I have never used it. It's from USA, but power supply transformer is re-wound to support 220V. Lack of inventory numbers or stickers suggests that it was bought by private buyer - strange for so expensive device.

Inside, manufacturer put many good components from different sources. There are many adapters between connectors to make it work. There's Indus mechanics inside, more reliable than Tandon one used in early versions.

The office software I have is mostly non-copy protected except spreadsheet, so enclosed image is for disassembly purposes only and will NOT WORK. Only this disk is protected because spreadsheets in 80s were killer applications, especially for 8-bit home computers.



Word processor


Spreadsheet

Disk scans

Power supply:

1 - GND
2 - +12V DC, 2A.

 

To boot a disk:
1. With Atari off turn the drive on and wait for it to reach track 39.
2. Insert boot disk
3. Start Atari. Drive should start booting when Atari shows "Ready" string.

Links:
 - http://trub.atari8.info/index.php?ref=indus_cpm_en - Here you can get information how to get CP/M running on Indus.


Commodore 1551
Commodore 16/Plus4
Manufactured by: Commodore

Format: 5.25", 170kB (same as 1541)
Connected to: C16/+4 Cartridge port
Capabilities:
 - Faster than 1541 (faster interface)
 - Working with Plus/4 integrated software
 - Better mechanism than in 1541
 - 6510T CPU inside
 - Disk compatibility with 1541

 

This floppy drive was dedicated to work with Commodore 16/Plus 4 computer. It was not much popular because of its price and incompatibility with more popular Commodore 64 computer.

It had better mechanism than original 1541 and had less overheating problems, mostly due to less power consumption.

 

 


Commodore 1541 II
Commodore 64
Commodore 128
Manufactured by: Commodore

Format: 5.25", 170kB (same as 1541)
Connected to: Commodore serial port
Capabilities:
 - Better mechanism than in 1541
 - External power supply - no overheating problems.
 - DIP switches on the rear solved problems with soldering jumpers inside.

 

 

 

Second Commodore's upgrade of 1541 disk drive. First one was replacing mechanism with modern one, with rotating lock. Second upgrade was to remove power supply from cover removing overheating problems almost completely.
External power supply can be placed anywhere so the drive is smaller too.
As 1541 could be switched to other drive number with inside jumpers, these jumpers could be cut and re-soldered. 1541-II had DIP switches, allowing to change drive number without removing cover.

Power Supply:

1 - +5V DC 1A
2 - GND
3 - nc
4 - +12V DC 500mA

 

Usage:
To load disk contents:
LOAD"$",8
LIST

To format new disk:
OPEN1,8,15,"N:DISK,01":CLOSE1
DISK is a disk short name
01 is disk's unique number (2 digits)

Drive's ID (in all examples it's default 8) can be changed with DIP switches at the bottom.


Commodore 1541
Commodore 64
Commodore 128
Manufactured by: Commodore

Format: 5.25", 170kB
Connected to: Commodore serial port
Capabilities:
 - 170K single sided floppy drive
 - 6502 microprocessor inside
 - GCR floppy disks recording
 
First popular Commodore's drive for Commodore 64 computers. It was very slow and had overheating problems. Early models had problems with disk removal mechanism (made by Alps Electric) and overheated a lot.
To deal with overheating users usually put pencils to mounting holes making air convection from bottom to top possible, but it wasn't much efficient.
1541 used single side of disk. It was possible to cut a second write protection hole in disk and flip it to format and use second side.

 
 

Usage:
To load disk contents:
LOAD"$",8
LIST

To format new disk:
OPEN1,8,15,"N:DISK,01":CLOSE1
DISK is a disk short name
01 is disk's unique number (2 digits)

Drive's ID can be changed with inside jumpers (these can be cut or soldered back).

 

Commodore 1571
Commodore 64
Commodore 128
Manufactured by: Commodore

Format: 5.25", dual side (330K)
Connected to: Commodore serial port
Capabilities:
 - Two heads for dual side writing
 - GCR and MFM capabilities (to make CP/M working in Commodore 128)
 - Faster than 1541
 - 1541-compatible mode

 

This is Commodore's high-end floppy drive, made to use with Commodore 128 computer. It had faster serial communication and MFM support, allowing to read CP/M disks.

There were 2 types of these drives. Earlier had a linear, transformer based power supply which was overheating much. Later model had switching power supply installed instead of transformer one.

My unit came to me much damaged. It had broken logic and many dry solders in power supply. If your 1571 is not working OK and it has transformer-based power supply, check the power supply first - especially transformer soldering.

 
 

Additional links:
 - http://www.zimmers.net/anonftp/pub/cbm/demodisks/c128/index.html - Here you'll find CP/M for C128.

 

External FDD for Amiga
Amiga 500
Amiga 600
Manufactured by: ?

Format: 3.5" 880K
Connected to: Amiga's External FDD port
Capabilities:
Working as Amiga's secondary floppy disk drive.

 

 

 

 

 

I have no idea who manufactured it. It's from Germany, and it's a normal Amiga external floppy disk drive with electronics only needed to join external connector to internal (ribbon) floppy drive cable.

 

 
 

 

 

Datalux SV-702
Amiga 500
Amiga 600
Manufactured by: Spectravideo

Format: 3.5" 880K
Connected to: Amiga's external FDD port
Capabilities:
Working as Amiga's secondary floppy disk drive.

 

 

 


 

This drive is nothing unusual - inside, there is only small circuit allowing to connect internal drive to external connector.

 

 
 

 

 

Acorn BBC Master 5.25" Drive
Acorn BBC Master (and some others)
Manufactured by: ??

Format: 5.25" 40-track 160kB
Connected to: BBC Master's FDD port
Capabilities:
Using smallest ADFS format, 160kB per disk.

 

 


 

It's a normal Teac drive in an enclosure, the ribbon cable is long to reach Acorn's case, it has a DIN socket on the rear to provide power (screws are mine! When I got it it was hanging outside on wires), ribbon cable is pushed between upper and lower part of casing. It's not original, but it works.

 

 


(rear view)

 

 

 

Acorn BBC Master Compact 3.5" Drive
Acorn BBC Master Compact
Manufactured by: Acorn

Format: 3.5"
Connected to: BBC Master Compact FDD port
Capabilities:
 - 3.5" disk support - there's a drive and ribbon cable, controller is built into microcomputer
 - Powering BBC Master Compact - power supply is giving 5V DC at 2A, with wire to plug into Master Compact.

 


 

 

 

 

 

 

 

RFT KC85 Floppy Disk Basis and Drive
Robotron RFT KC85/3 and KC85/4
Manufactured by: RFT VEB Mikroelektronik

Format: 5.25"
Connected to: RFT KC85 computer
Capabilities:
 - Can read, format and write 5.25" disks
 - Runs a CP/M clone (MicroDOS) on its 4MHz Z80 processor, while computer becomes a terminal.
 - Possible to expand RAM using module up to 4MB. This RAM works then as a RAM disk A: for MicroDOS system.

I don't have information how to make disk images in/out physical disks.
 

The strange thing here is the floppy drive itself. It is like Teac drives which were purchased by Robotron and re-branded, but it looks that it is not Teac. There are some Japanese parts, like opto-barriers or mechanical detectors, but many chips are Soviet or German. It looks like at the end of GDR, they finally launched licensing Japanese disk drives.


Original FDD head protective card.

 

 

http://www.mpm-kc85.de/html/D004FD.htm - Manuals and disk description
http://www.sax.de/~zander/kc85/kc85_hw.html - Schematics and ROMs
http://www.sax.de/~zander/kc85/tip/tip7.html - Make a connector