Teac FD-55 series
The Teac FD-55 is a series of 5.25" floppy drives, with varying characteristics depending on the suffix.
|Suffix||Density||Sides||Tracks per side||RPM||Notes|
|A||N/A||Double||Single||40||300||PC standard - original 180kB format|
|B||BR||Double||Double||40||300||PC standard - 360kB format|
|E||N/A||Double||Single||80||300||Not used with the PC|
|F||FR||Double||Double||80||300||Not used with the PC|
|G||GR||High||Double||77||360||Not used with the PC|
|GF||GFR||Double/High||Double||80||300/360||PC standard - 1.2MB/360kB|
|GS||?||Double/High||Double||80||300/360||SCSI version of FD-55GF (1.2MB/360kB)|
A-type (1S DD 40T)
- Main article: Teac FD-55A
This drive is a single-sided, 40-track, double-density drive, with a wide head suitable for reading and writing double-density disks in their native format. As it is only single sided, it will only work with 180kB (9-sector) and 160kB (8-sector) disk formats.
B-type (2S DD 40T)
A double-sided version of the A-type. This variant is the most common double-density drive, as it works with the standard 360kB disk format. The head width is double that of a HD drive, so it can read and write both single- and double-sided DD disks in their native format.
E-type (1S DD 80T)
A very uncommon drive, this one is double-density however it uses the stepper and head mechanism from an 80-track drive. This means it can read 40-track double-density disks, however when writing to them it will potentially suffer from the same problems as writing double-density disks on a HD drive - specifically the tracks will be half the size of the native 40-track drives.
To further limit its use, this variant is also single-sided, so it can't read 360kB disks, only the older single-sided 180kB formats.
It was advertised as a double-density 80 track drive - a format which was never adopted by the PC.
When the later R-update was introduced to the series, the E-type was not included in the update.
F-type (2S DD 80T)
A double-sided version of the E-type, this drive is essentially a 1.2MB high density drive, but with high-density support stripped out. This means it can only read and write double-density (360kB) disks, but with half-width tracks just like a HD drive does.
This format (DD 80T) was never adopted by the PC, so F-type drives are not very common.
G-type (2S HD 77T)
The only variant in the series that can write high-density 1.2MB media. The G-type on its own can only write to HD media, and does not have support for double-density disks. It also appears to be limited to 77 tracks, whereas the PC 1.2MB format uses 80 tracks.
GF-type (2S DD/HD 80T)
As the G-type could only access HD 1.2MB media in a world where DD 360kB media was common, its functionality was combined with the F-type to produce the GF-type. This drive could switch between HD and DD media, run at 300 (DD) or 360 (HD) RPM, and extended the HD format from 77 tracks to the 1.2MB PC standard 80 tracks. It allowed all previous disk formats supported by the FD-55 series to be read by a single drive.
It still suffered from the same issues as the E-type and F-type, in that its half-width head made writing to DD media unreliable, however DD disks could be read without problems.
This drive is a GF-type fitted with an interface converter that translates between the standard floppy interface and SCSI. It allows the drive to be one of up to seven connected to a narrow-SCSI bus.
Not much is known about this interface, so photos are welcome!
The original series of drives were later updated by Teac to take advantage of developments in circuit design and to reduce power consumption, and they were re-released with an R suffix to indicate the revised design was in use.
With the update, the single-sided A-type and E-type drives were discontinued and new versions of these drives were not produced. These two drives worked with formats that were long obsolete in the PC world, and as disks in those formats could still be read by B-type and F-type drives respectively, there was little reason to produce new versions of the drives.
The front panels of all drives in the series are the same, and come in three colours - white, grey and black.
- Manuals and brochures at Bitsavers