Confusingly, the Datassette at various times was sold both as the C2N DATASETTE UNIT Model 1530 and as the 1530 DATASSETTE UNIT Model C2N. Note the difference in spelling, which is seen on the original product packaging.
The Datassette contained built-in A/D converters and audio filters to convert the computer's digital information into analog sound and vice versa (much like a modem does over a phone line). Connection to the computer was done via a proprietary plug fitting directly with a corresponding part of the computer's circuit board edge. The absence of recordable audio signals on this interface made the Datassette and its few clones the only cassette recorders usable with CBM's machines, until aftermarket converters made the use of ordinary recorders possible.
The inexpensive and widely available audio cassettes made the Datassette a good choice for the budget-aware home computer mass market. In Europe, the Datassette was the medium of choice for several years after its launch, although disk drives were available. In the US, however, disk drives quickly outshadowed the Datassette, the Commodore 64 being the first home computer to popularize the medium and make it affordable – albeit still expensive (roughly 10 × the price of a Datassette).
The Datassette was a very slow and fairly unreliable medium (the latter caused by the sensitivity of the encoded analog signal to disturbances by magnetic fields and tape failure). Contemporary disk drives were an order of magnitude less slow and unreliable. Some years after the Datassette's launch, however, special turbo tape compression software appeared, providing much faster tape operation (loading and saving). Such software was available for loading commercial prerecorded applications (mostly games), as well as for use with one's homemade programs and data.
Many a potential software pirate fancied themselves smart for trying to copy software recorded on tapes through an ordinary twin tape deck. This seldom met with success: cheap tape decks transported the tapes too irregularly for the sensitive timing needs of the Datassette, while expensive decks had their own filters to enhance music quality – which actually degraded the quality of the data coding. Disks were much easier to copy, which spurred on the development of copy protection.
The are at least four main models of the 1530/C2N Datassette, listed chronologically below. The first two were made as PET peripherals, while the latter two were mostly marketed towards VIC-20 and C64 owners, although all were compatible with all those computers.
Similar in physical appearance but both connector-wise and storage-wise incompatible with the 1530/C2N models is the 1531 model, made for the Commodore 16 and Plus/4 series computers:
Description and history
Main models
In addition to this, some models came with a small hole above the keys, to allow access to the adjustment screw of the tape head azimuth position. A screwdriver could thus easily be used to effect the adjustment without opening the Datassette.