[Coco] 6809 CC Reg Overflow bit

Salvador Garcia salvadorgarciav at yahoo.com
Tue Nov 6 17:14:58 EST 2018


Hi all. I am reading William Barden's Assembly Language for the Color Computer and on the bottom of page 57 he presents the following code <snipped>:

LDA #100
ADDA #100   100 + 100 = 200  = V!

Then on the second paragraph below the code he states:


"... The first ADD added an immediate 100 to the 100 in the A register for a result of 200. This is an overflow condition, and the V Condition Code should have been set to a 0, indicating no overflow:"

If the V Condition Code is set to a 1 to indicate overflow, and the 100 + 100 op caused an overflow, why is he saying that the V Condition code is set to a 0?

Am I missing something? As always, thanks! Salvador







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