7.1.6) What is the Atari cassette utilization/filesystem?

(Section sources include: De Re Atari, OS Users Manual, XL Addendum) The following are characteristics of the cassette utilization/filesystem as implemented by the Atari Operating System. - Mark = 5327Hz (audible sound frequency) - Space = 3995Hz (audible sound frequency) - Bit = space(0) or mark(1) - Byte = 10 bits: - 1 start bit (space) - 8 data bits - 1 stop bit (mark) - Record = 6-132 bytes, as follows: - Speed measurement byte, first of two. Marker character = $55 (hex) - Speed measurement byte, second of two. Marker character = $55 (hex) - Control byte. One of three values: 1) $FC = Record is a full data record. 2) $FA = Record is a partially full data record, and the next record should be an end-of-file record. 3) $FE = Record is an end-of-file record. - Data bytes. 128 bytes for a full data record or an end-of-file record, or 2-128 bytes if a partially full data record, where the last byte is not really a data byte, but rather contains the number of actual data bytes (1-127). - Checksum byte - Pre-Record Write Tone (PRWT) = pure mark tone - Post-Record Gap (PRG) - Record Frame = PRWT + Record + PRG - Inter-Record Gap (IRG) = PRG + PRWT - Normal IRG Mode: Tape comes to stop after each record frame - Short IRG Mode: Tape is not stopped between record frames. (Short IRG Mode is supported by the Atari BASIC commands CSAVE and CLOAD.) - Normal IRG PRWT = 3 seconds of mark tone - Short IRG PRWT = 0.25 second of mark tone - Normal IRG PRG = Up to 1 second of unknown tones (motor stop/start time) - Short IRG PRG = pure mark tone, duration set by user program (may be zero) - File consists of: 1) 20-second leader of mark tone 2) Any number of data record frames (each frame contains one data record) 3) End-Of-File record frame (contains an end-of-file record)