IMS IMSAI 8080 User Manual page 406

The CRI Port writes Biphase Encoded Data
to the tape. This can be used to generate
Byte/Lancaster or Tarbell data formats.
The Biphase encoding generates Byte/Lan­
caster data formats by sending alternating
l's and 0's when a zero bit is to be recor­
ded. It sends all l's when a one bit is to
be recorded. In this standard, the max­
imum data rate is 30 bytes per second.
The CRI can also operate in the Tarbell
Standard, using one bit of phase encoding
per data bit. This standard allows the User
to record data at the standard rate of
187 bytes per second or faster if the rec­
order used is of sufficient quality.
The recorder section can have two cassette
recorders connected to it at one time, thus
providing the User with the basic cap­
ability for a cassette operating system.
MIO
Functional Description