> I bet PowerPC still has some 68000 stuff into it.
You'd lose. There were two platforms who made that jump, but the architectures have no lineage in common at all.
You'd lose. There were two platforms who made that jump, but the architectures have no lineage in common at all.
There seems to have been a lot of work on emulation by Gary Davidian from an early stage - starting with the AMD 29000 then 88k and then finally on PowerPC - according to his CHM oral history.
https://youtu.be/XYWp_R33mDs?si=4czECGOaHiM-MQqt
Roughly lines up with the history recounted here:
https://lowendmac.com/2014/ibm-apple-risc-and-the-roots-of-t...
Apple was planning to go with a radical new design, breaking with the past in both software and hardware, but Gary Davidian & co. saved them from their own foolishness via a skunkworks project that actually could ship.
By complete co-incidence I have a blog post on the various Mac CPU transitions in draft that should be out tomorrow.
One mildly amusing point, which I don't think is mentioned in either link is that the Cognac project was so called because the surname of John Hennessy, of Stanford RISC and MIPS fame, is also, of course, the name of a brand of Cognac.
Already in 1964, in IBM System/360, the condition-code was a part of a bigger register, the "processor status word". The terms are much older than that.
Also in MC68000, the CCR is a part of the bigger status register, which, unlike the CCR, can be accessed only by privileged programs.
In POWER, the condition register also holds only the condition-code part of the status, but it has room for 8 groups of condition codes, to allow high speed even for cheaper in-order CPUs, which do not have register renaming (where otherwise a shared condition-code register would prevent the concurrent execution of instructions).