3 ms·
The article states: >"The ARM2 had pretty much the same instruction set as the ARM1, although featured new multiplication and (later) atomic swap instructions.
by bogomipz 8y ago
The article states:
>"The ARM2 had pretty much the same instruction set as the ARM1, although featured new multiplication and (later) atomic swap instructions."
Does this mean that the ARM1 didn't support any atomic operations or were they using something else besides "compare and swap"?
- jecel 8y agoThe ARM1 did not have any atomic operation. You only need those if you have more than one processor. It also lacked the multiply and multiply-accumulate instructions, as stated above. These took multiple cycles, which is not very RISC-like. That is also true of the load multiple and store multiple instructions of the ARM2 (I don't remember if the ARM1 had them). The ARM2 also added the coprocessor interface.
- jecel 8y agoOops - in the analysis of the PLA2 in the ARM1 there are both the load/store multiple instructions and the coprocessor stuff. In fact, together they take up about half of the logic. So I was remembering it wrong, then. http://daveshacks.blogspot.com/2016/01/inside-armv1-instruction-decoding-and.html http://daveshacks.blogspot.com/2016/01/inside-armv1-instruct...
- bogomipz 8y agoAh of course there were no mutli-cores back then. That makes total sense. Thanks.