Tandy 1000 HX Technical Reference Manual page 395

Video Display
These routines provide an interface to the video display, which is
the output half of the console (CON) device. MS-DOS considers
the video display to be the default standard output (STDOUT)
device.
Software Interrupts:
10 hex (16 dec)
Function Summary:
Control Routines:
AH = 0: Set CRT Mode
AH = 1: Set Cursor Type
AH = 2: Set Cursor Position
AH = 3: Get Cursor Position
AH = 4: Read Light Pen Position
AH = 5: Select Active Page
AH = 6: Scroll Active Page Up
AH = 7: Scroll Active Page Down
Text Routines:
AH = 8: Read Attribute/Character
AH = 9: Write Attribute/Character
AH = 10: Write Character Only
Graphics Routines:
AH = 11: Set Color Palette
AH = 12: Write Dot
AH = 13: Read Dot
Other Routines:
AH = 14: Write TTY* to active page
AH = 15: Get CRT Mode
AH = 16: Set Palette Registers
*Screen width is determined by the mode previously set. Some
"control" characters (ASCII 00H-1FH) perform the usual spe-
cial terminal function. These include (but are not limited to)
BEL (07H), BS (08H), LF (0AH), and CR (0DH).