High Density floppy drive for the Atari ST

 

This is our prototype drive, Built and working on 27/06/02

 

 

Here is our Prototype 1.44meg drive. Drive measures 120x30x180mm (WxHxD) approx.. Slimline anodized aluminum case with black ABS trim at front and rear. Front shows the 1.44 floppy drive. Rear shows cable and DC power socket.

The floppy connector is the normal 14pin DIN plug found on the Atari ST range of computers. The extra jack plug with the white lead is the extra wire needed for the ST to make use of 1.44meg drives. The ST is only designed with 720K drives in mind so the connector does not have enough pins to make use of 1.44meg drives. To correct this the extra wire is needed ( the white one ). This plugs into the back of the ST when the 1.44meg floppy board is fitted.

The power supply is a external 5volt 1amp wall adapter (not shown in image). This plugs into the socket on the back of the drive. A external power supply is used since the ST's power supply has enough to cope with without the extra load of another floppy drive.

The drive supports both Double Density (720K) and High Density (1.44meg) discs. The drive can be used as a 720K drive without the 1.44meg driver board but will of course be unable to read 1.4meg discs. With no 1.44meg driver board installed the drive will only read 720K discs and the extra white lead will be unused in this instance.

Drive specifications.

Data transfer rate:
2-MB mode 500,000 bits/sec (for MFM)
1-MB mode 250,000 bits/sec (for MFM)
Average access time 94 ms.
Maximum format capacity 22 sectors -82 tracks-1833472 Bytes

Notice with 2MB mode the drive transfers data twice as fast as a normal 1MB disc! Meaning as a bonus for using High Density discs the transfer rate will also increase thus programs will load faster etc.