INT 10 - VIDEO - HP Vectra EXTENDED BIOS - SET MONITOR INFO
        AX = 6F02h
        BL = new value for extended control register (see below)
Return: nothing
Notes:  this function is only valid when an HP MultiMode Video Display Adapter
          is installed
        the Extended Control register is at I/O address 3DDh
SeeAlso: AX=6F01h,AX=6F03h

Bitfields for extended control register:
 bit 0  screen resolution (0 = 200 lines, 1 = 400 lines)
 bit 1  underline enable (if set, 'blue' bit of fg color = underl)
 bit 2  font (0 = Standard-8, 1 = HP-Roman-8)
 bit 3  memory disabled for CPU access
 bit 4  allow access to full 32K memory instead of wrapping at 16K
 bit 5  select second 16K page instead of first
 bits 6,7 unused

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