Programming Interface Information - Zenith Z-100 Reference Manual

Programming Interface Information

T he information in t his section repeats much of th e f oregoing, but i s
arranged in a format designed to darify and link together related concepts and
operations. Specific instrudions are presented here, which, together with the previ-
ous data, will enable you to perform spedfic programming operations.
The 2-letter registers referenced here are 8088 microprocessor registers.
Video Interrupt Vector
Any of the the video features may be programmed by the use of the spedfic
video function parameters, followed by an 8088 instruction call using the INTerrupt
command. The necessary parameters for a desired function are first placed in
the appropriate registers and the function code for that operation is placed in
the AH register. Then the INT instruction for the video I/O, interrupt vector 10
hexadecimal, 16 decimal, is called.
The video VO interrupt vector will allow several modes of operation to be im-
plemented:
• Text d isplays using the RGB compatibility mode. All of these displays allow
the use of multiple independent video pages.
• 80 ch a racter by 25 row text mode on an IBM monochrome display adapter
card. Allows a single video page only.
• Grap h ics displays using RGB color compatibility mode. 128-character
graphics character set contained in character ROM (on the video card) is
used. An additional 128 user-defined characters may be created and used.
Table 7.17 defines the function codes (AH value) recognized by the system.
Video Graphics Programming
Page 7.33