(thing) by ariels Mon Dec 18 2000 at 11:21:15
branch if carry clear.
A 6502 opcode. To perform 2-byte addition, you can do this: 
    LDA a
    ADC b
    STA c
    BCC s1
    LDA a+1
    ADC b+1
    STA c+1
 s1:RET
I like it!