IBM RT Series Hardware Reference Manual page 360

TNL SN20-9844 (March 1987) to 75X0235
Vector Draw Graphic Operations
Vector Draw (X'35')
This graphic operation draws a straight line contained within the bit map (1024 x 1024). The
line is defined by four parameters, X from, Y from, X to, and Y to. The logical operators on the
bit map for the line draw are set line on (F), set line off(O), and 'XOR' line (A).
Example: Draw a Line From (48,256) To (16,512).
Queue Queue Action
By
Register Register Reg
Address Data Queue Processing Start Min Max End
Que Ptr
X'1030' Load X from R 1 Xl =48
o
1023
X to
Que Ptr-1 X'0100' Load Y from RO Y1 = 256
o
1023 Y to
Que Ptr-2 X'5010' Load X to R5 X2= 16
o
1023
Que Ptr-3 X'6200' LOAD Y to R6 Y2 = 512
o
1023
Que Ptr-8
X'D35F' Execute Line Draw Set line on No decrement
At the completion of the line draw, the X,Y 'to' coordinate is saved in the X,Y 'from'
coordinate registers. This permits the next graphic operation to use this saved X, Y 'to'
coordinate information for the next X,Y 'from' coordinate with out having to reload (polyline)
as shown below.
Example: Continue Drawing a New Line From (16,512) to (256,512)
Queue Queue
Action
By
Register Register
Address Data Queue Processing Start Min Max
Que Ptr X'5100' Load X2 into R5 X2=256
o
1023
Que Ptr-1
X'6200' Load into R6 Y2 = 512
o
1023
Que Ptr-2 X'D35F' Execute line draw Set line on No decrement
Note: X,Y 'to' coordinate is saved in the X,Y 'from' registers.
48
Extended Monochrome Graphics Adapter