Mass storage of the Hp-85 is provided by a tape cartridge system using the 98200A data cartridge. Each cartridge holds about 200K bytes of information. This information may be any combination of source program files, binary program files and data files. The directory stored on the tpae wiull hold 42 six-character file names. By using the CATalog command, the user can easily review the contents of any data cartridge. A portion (256 bytes) of the directory is automatically stored in the system RAM. This significantly reduces the time required to access a file.
The HP-85 tape electronics can drive the tape at two different speeds. When searching for a file the tape speed is 1524mm/s (60 in/s). Once the file is found, the speed for read/write is slowed to 254 mm/s (10 in/s). This corresponds to a data transfer rate of 650 bytes per second.
An autostart capability is provided by the system firmware. When power is applied to the HP-85, it automatically rewinds the tape and reads the tape directory, looking for a program named Autost. If the file exists, the computer will find it on the tape, load it into memory, and immediately start running the program. Autost programs are supplied with some HP software pacs or can be generated by users for their particular needs.
Security is available for the files stored on the tape for the files stored on the tape cartridge. When storing a file the user can specify one of four types of security for that file. Also, the entire cartridge can be manually protected against inadvertant overwriting by setting the write-protect switch that exists on each cartridge.