Ncr Software - NCR PC4I Technical Reference

VIDEOTEX
Videotex Controller register R58 is significant only
as its bit 6 must be set, and bit 7 has an
enabling/disabling effect regarding bit
6
of the
registers R33 - R57: if bit 7 of R58 is set, the
adoption of the lower screen fringe area color does
not apply.
NCR SOFTWARE
The NCR Videotex package includes a number of
executable files providing a user friendly interface
conforming to the requirements of the specific
country.
One of the files supplied provides an interface to
useful Videotex Controller, VLP, and modem functions.
This program, like the others in the Videotex
package, is designed to run under the disk operating
system. Once loaded, it remains in memory as a
resident process, providing a library of routines
which can be called from subsequently loaded
processes. Refer to your Videotex User's document for
the actual filename for your country.
The functions are executed in much the same way as
disk operating system function calls: loading certain
CPU registers, issuing an interrupt, and accepting
return parameters.
• The function number is placed in BX
• The interrupt issued is type 75H
Other parameters are function-specific. Where 8-bit
parameters are passed in a 16-bi t CPU register, the
upper 8 bits of the register are zero.
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