Editing Commodore Datasette (section)

== Features ==
[[File:Commodore-Datasette-C2N-Mk2-Back.jpg|thumb|The connection cable to the Datasette]]

The Datasette is probably the most sophisticated tape-storage method of any microcomputer.{{r|deceukelaire198502}} Typical [[cassette tape|compact cassette]] interfaces of the late 1970s use a small controller in the computer to convert [[digital data]] to and from [[analog audio]] tones. The interface connects to the cassette deck using normal audio cables like [[RCA connector|RCA jacks]] or [[phone connector (audio)|3.5mm phone jacks]]. Such a system is compatible with the [[Apple II]]<ref>{{cite magazine | magazine = Apple Orchard | title = The Apple II Cassette Interface | url = https://archive.org/details/Apple-Orchard-v2n1-1981-Spring/page/n57 | page = 57-58 | publisher = International Apple Core | volume = 2 | issue = 1 | date = Spring 1981 | issn = 0277-1950 | oclc = 647837472 | via = [[Internet Archive]] | df = dmy-all}}</ref>{{rp|pages=[https://archive.org/details/Apple-Orchard-v2n1-1981-Spring/page/n57 57-58]}} and [[TRS-80 Color Computer]], as well as many [[S-100 bus]] systems, and allows them to be used with any cassette player with suitable connections,<ref>{{cite magazine |magazine= Popular Mechanics |date=February 1983 |title=The Five Friendliest Computers |first=Herb |last=Friedman |pages=97}}</ref> but using analog tones—similar to how [[dial-up modem]]s work—often results in [[read error]]s instead of successful loading of data.{{r|deceukelaire198502}}

[[file:Commodore Basic screenshot.jpg|thumb|left|The Datasette loading process]]

In the Datasette, instead of writing two tones to tape to indicate bits, patterns of [[Square wave (waveform)|square wave]]s are used, including a [[parity bit]]. Programs are written twice to tape for [[error detection and correction|error correction]]; if an error is detected when reading the first recording, the computer corrects it with data from the second.{{r|deceukelaire198502}} The Datasette has built-in [[analog-to-digital converter]]s and [[audio filter]]s to convert the computer's digital data into analog audio and vice versa. Connection to the computer is done via a proprietary [[edge connector]] (Commodore 1530) or [[mini-DIN connector]] (1531). The absence of recordable audio signals on this interface makes the Datasette and clones the only cassette recorders usable with Commodore computers, until aftermarket converters made the use of ordinary recorders possible.

Because of its digital format the Datasette is both more reliable than other data cassette systems and very slow,<ref name="deceukelaire198502">{{cite news | url=http://www.atarimagazines.com/compute/issue57/turbotape.html | title=How TurboTape Works | work=Compute! | date=February 1985 | access-date=30 October 2013 | author=De Ceukelaire, Harrie | pages=112}}</ref><ref name="128book">{{cite book | chapter-url=https://archive.org/stream/The_Official_Book_for_the_Commodore_128#page/n21/mode/2up | title=The Official Book for the Commodore 128 Personal Computer | publisher=Howard W. Sams & Co. | author1=Waite, Mitchell | author2=Lafore, Robert | author3=Volpe, Jerry | year=1985 | pages=11–32 | isbn=0-672-22456-9 | chapter=Peripherals: Displays, Disk Drives, Printers, and More}}</ref> transferring data at around {{nowrap|50 bytes}} per second. After the Datasette's launch, however, special ''[[turbo tape]]'' software appeared, providing much faster loading and saving.{{r|deceukelaire198502}} Such software was integrated into most commercial prerecorded applications (mostly games), as well as being available separately for loading and saving the users' homemade programs and data. These programs were only widely used in Europe, as the US market had long since moved onto disks.

Datasettes can typically store about {{nowrap|100 [[kilobyte|kByte]]}} per {{nowrap|30 minute}} side.<ref>{{Cite web|url=http://starbase.globalpc.net/~vanessa/hobbies/commodore-info.html|title=Basic Commodore information}}{{dead link|date=June 2017 |bot=Jennica |fix-attempted=yes }}</ref> The use of ''turbo tape'' and other fast loaders increased this number to roughly {{nowrap|1000 kByte}}.

The Datasette has only one connection cable, with a {{convert|0.156|in|adj=on}}&ndash;spacing<ref>{{cite magazine|title=Rupert Report: Computers in Control|magazine=Ahoy!|date=July 1987|page=32|last=Rupert|first=Dale|issn=8750-4383|publisher=Ion International|location=New York|url=https://archive.org/stream/ahoy-magazine-43/Ahoy_43_July_1987#page/n35/mode/2up|access-date=2018-04-12}}</ref> PCB [[edge connector]] at the computer end. All input/output signals to the Datasette are all digital, and so all [[digital-to-analog conversion]], and vice versa, is handled within the unit. Power is also included in this cable. The [[pinout]] is ground, {{nowrap|+5 V [[direct current|DC]]}}, motor, read, write, key-sense.<ref>[http://old.pinouts.ru/Storage/CassetteC64_pinout.shtml pinouts.ru - C64 Cassette pinout], 2012-01-15</ref> The sense signal monitors the play, rewind, and fast-forward buttons but cannot differentiate between them. A mechanical interlock prevents any two of them from being pressed at the same time. The motor power is derived from the computer's unregulated {{nowrap|9 V DC}} supply<ref>{{cite book|title=Commodore 64 Programmer's Reference Guide|year=1984|isbn=0-672-22056-3|publisher=Commodore Business Machines|location=West Chester|at=Commodore 64 Schematic Diagram|url=http://www.zimmers.net/anonftp/pub/cbm/schematics/computers/c64/C64SchematicP2.png|access-date=2018-04-12}}</ref> via a transistor circuit.<ref>{{cite book|title=SAMS Computerfacts CC4: Computer: Commodore 64|page=2|year=1984|publisher=Howard W. Sams|location=Indianapolis}}</ref><!-- Sams says it measures 6.45V under load (p. 9). -->