Owner's manual

130 Allegro DOS Owner’s Manual
Function AH=2Fh
Subfunction: AL = 00h (read status byte)
Output: AL = Status Byte, where:
Subfunction: AL = 01h (read video contrast)
Output: AL = Video Contrast
The range of video contrast is from 0 to 63.
Subfunction: AL = 0Ch/AL = 0Dh (turn backlight off/on)
AL = 0Ch turns the display backlight off. AL = 0Dh turns the display
backlight on. Returns nothing.
Subfunction: AL = 0Eh/AL = 0Fh (set heater off/auto)
AL = 0Eh turns the display heater off. AL = 0Fh sets the display
heater to automatic. Returns nothing.
❖ Note: In automatic mode, the heater is active when the display
temperature is below -3° C.
Subfunction: AL = 10h/AL = 11h (set key beep off/on)
AL = 10h turns the key beep off. AL = 11h turns the key beep on.
Returns nothing.
Subfunction: AL = 12h (power down system)
This function causes the Allegro to immediately power off just like
it does when the On/Off key is pressed and the Allegro is in On/Off
mode. If external power is connected to the Allegro, this function
causes the Allegro to go into a semi-low power state where it appears
to be off, but it is actually on. Any event that normally causes the
Allegro to turn on (pressing the On/Off key, com port ring in, etc.)
causes the Allegro to reboot. When the external power is removed,
the Allegro powers off.
Subfunction: AL = 13h (put system in reboot mode)
When it is executed, the Allegro is set to reboot mode. In this mode
the on/off key causes power to be turned off. Returns nothing.
Subfunction: AL = 14h (put system in suspend/resume mode)
When it is executed, the Allegro is set to suspend/resume mode. In
this mode, the power is not completely shut off. The Allegro is still
running but at very low power, so it appears to be off. When the key
is pressed, the Allegro resumes where it left off.
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