4 ms·
I'm not sure this is true, since you could simulate it on other CPUs. I believe most modern OSs don't use the top byte, so you can store things in there (as lon
by verdagon 4y ago
I'm not sure this is true, since you could simulate it on other CPUs. I believe most modern OSs don't use the top byte, so you can store things in there (as long as you clear it before trying to dereference it).
- vardump 4y agoWhile that may be true, my experiences from Motorola 68k times still make me shiver. 68k used just bottom 24 bits for an address. Later models used full 32 bits, breaking anything that used the top 8 bits for something else. The introduced incompatibility was that bad and hard to get rid of. So pardon me for feeling uneasy.
- irdc 4y agoYes, but on the Mac (where these bits were used) the entire system participated, whereas this is per-process and needs to be explicitly enabled.