Tandy 1000 HX Technical Reference Manual page 397

Set Cursor Type
Set the cursor type and attribute.
Entry Conditions:
AH = 1
CH = bit values:
bits 5-6 = cause an invisible or erratically blinking cursor
bits 5-6 = 00 produces a visible, blinking cursor.
bits 4-0 = start line for cursor within character cell
CL = bit values:
bits 4-0 = end line for cursor within character cell
Set Cursor Position
Write (set) cursor position.
Entry Conditions:
AH = 2
BH = page number (must be 0 for graphics modes)
DH = row (0 = top row)
DL = column (0 = leftmost column)
Get Cursor Position
Read (get) cursor position.
Entry Conditions:
AH = 3
BH = page number (must be 0 for graphics modes)
Exit Conditions:
DH = row of current cursor position (0 = top row)
DL = column of current cursor position (0 = leftmost column)
CX = cursor type currently set [1]:
See Set Cursor Type (AH = 1) above.
Read Light Pen Position
Reads light pen position.
Entry Conditions:
AH = 4