On 24/03/2016 14:31, Alex Bligh wrote: > Sorry, I should have been clearer on the states: > > bits > 210 > > 1-- Unallocated, and hence reads as zero > -1- Allocated, and reads as zero > --1 Allocated, and reads as non-zero > > So 100 means 'definitely unallocated, will read as zero'. > > If you are saying that there is also a state called 'Unallocated, but reads > as non-zero',
Yes. > that could be handled by adding a fourth bit. Same idea. One > would presume this would only ever be set in conjunction with bit 2. > My point in general was to represent all the possible states and let the > client > determine what it wants to do with the information. This seems overengineered... Paolo