Definetely one my pet peeves about Windows Installer is how it deals with instruction set architectures (ISAs). Looking at Windows NT history, supported ISAs have come (amd64, IA-64) and gone (Alpha, PowerPC, MIPS) – yet most of the time, there was more than one ISA being officially supported. Having to ship binaries for multiple ISAs therefore always has been on the agenda for many ISVs. Needless to say, supporting multiple ISAs requires special consideration when developing setup packages and providing separate packages – one for each ISA – has become common practice to approach this.
The stack pointer, esp on i386, denotes the top of the stack. All memory below the stack pointer (i.e. higher addresses) is occupied by parameters, variables and return addresses; memory above the stack pointer must be assumed to contain garbage. When programming in assembly, it is equally easy to use memory below and above the stack pointer. Reading from or writing to addresses beyond the top of the stack is unusual and under normal circumstances, there is little reason to do so.