Atari Program Recorder

The data rate was nominally 600 bit/s, but the simple error correction and short gaps between the resulting packets lowered this somewhat.

The original 410 was a modified Sears model 799.21672500 Solid State Cassette Recorder with a Japanese mechanism by Bigston.

This was replaced by a somewhat smaller and more rounded unit around 1981 using a new mechanism from Transtek or Chelco Sound in Hong Kong.

They can be distinguished by the colored sticker inside the drive bay, Chelco used silver while Sanyo was orange.

[1] When the XE series were released they were initially sold into existing markets and Atari introduced a number of XE-styled accessories to go with them.

[1] The XE line was later sold primarily in eastern Europe, South America and other markets that had not previously seen low-cost home computers.

This was enforced by leaving off the daisy-chaining port on the tape decks, forcing it to be the last device on the SIO chain.

Data sent to the cassette device driver toggled which of the two tones was played to DATAOUT while being timed by the clock.

During playback, the two outputs would toggle DATAIN on and off, which was automatically interpreted by the POKEY and reformed into a series of bytes for storage.

The first two bytes were 01010101 01010101, used for clock recovery by the POKEY to address tape stretch and other common problems in cassette systems.

Generally, BASIC programs were instead stored in their tokenized form which could be read and written as binary data using the Short IRG.

Directly after this header there is code expected for a potential multi stage boot that returns with the carry flag cleared in case of an error.

The system would then assert the MOTOR line to begin playback, reading from the tape for up to 35 seconds looking for the header packet.

[12] Another feature of the Atari SIO port was the AUDIOIN pin, which was connected to the left channel of the cassette.

This was originally used with a series of computer aided instruction (CAI) cassettes that were sold by Atari and later by third parties.

The associated program would then turn on the MOTOR line to begin playback and then read data until it saw a series of ones on the POKEY.

[17] The basic signaling rate of the system was 600 bit/s, but there was some additional overhead due to the inter-record gaps and the packet structure.

Among the best known was the Turbo 2000 system from Czechoslovakia, which increased the basic data rate of an XC12 to 2270 bit/s, almost four times as fast as the original standard.

[20] In 1983, Carl Evens posted a short note on ways to improve the reliability of reading data from the decks.

This reduces the width of their bell-curve-shaped frequency response and eliminates any overlap where a signal might produce output in both channels.