Hi I am new to this environment I am on Pharo 6.0 - 64 Mac OSX version, Downloaded over the weekend. Just did some learning and found that the description for bitAnd: is probably wrong. It reads exactly the same as bitOr: here are some tests as performed in the workspace Also included bitXor: for the fun of it bitAnd: arg Primitive. Answer an Integer whose bits are the logical OR of the receiver's bits and those of the argument, arg. Numbers are interpreted as having 2's-complement representation. Essential. See Object documentation whatIsAPrimitive. <primitive: 14> self >= 0 ifTrue: [^ arg bitAnd: self]. ^ (self bitInvert bitOr: arg bitInvert) bitInvert. 0 bitAnd: 0 -> 0 1 bitAnd: 0 -> 0 2 bitAnd: 0 -> 0 3 bitAnd: 0 -> 0 0 bitAnd: 1 -> 0 1 bitAnd: 1 -> 1 2 bitAnd: 1 -> 0 3 bitAnd: 1 -> 1 bitOr: arg Primitive. Answer an Integer whose bits are the logical OR of the receiver's bits and those of the argument, arg. Numbers are interpreted as having 2's-complement representation. Essential. See Object documentation whatIsAPrimitive. <primitive: 15> self >= 0 ifTrue: [^ arg bitOr: self]. ^ arg < 0 ifTrue: [(self bitInvert bitAnd: arg bitInvert) bitInvert] ifFalse: [(self bitInvert bitClear: arg) bitInvert] 0 bitOr: 0 -> 0 1 bitOr: 0 -> 1 2 bitOr: 0 -> 2 3 bitOr: 0 -> 3 0 bitOr: 1 -> 1 1 bitOr: 1 -> 1 2 bitOr: 1 -> 3 3 bitOr: 1 -> 3 bitXor: arg Primitive. Answer an Integer whose bits are the logical XOR of the receiver's bits and those of the argument, arg. Numbers are interpreted as having 2's-complement representation. Essential. See Object documentation whatIsAPrimitive. <primitive: 16> self >= 0 ifTrue: [^ arg bitXor: self]. ^ arg < 0 ifTrue: [self bitInvert bitXor: arg bitInvert] ifFalse: [(self bitInvert bitXor: arg) bitInvert]. 0 bitXor: 0 -> 0 1 bitXor: 0 -> 1 2 bitXor: 0 -> 2 3 bitXor: 0 -> 3 0 bitXor: 1 -> 1 1 bitXor: 1 -> 0 2 bitXor: 1 -> 3 3 bitXor: 1 -> 2 Picked it up when I was trying to explain the simplicity of the even method on smallInteger. Methods work just fine, but the description is wrong regards Koos brandt