3 ms·
Reading from L2 requires sending down a request and then waiting for the response. This makes me realize that the actual speed is 5.5 mm in 0.625 ns because it'
by brucedawson 5y ago
Reading from L2 requires sending down a request and then waiting for the response. This makes me realize that the actual speed is 5.5 mm in 0.625 ns because it's a two cycle delay in each direction. I'll update the article.
But, this request/response means that a ring bus seems unlikely because a unidirectional ring bus should make the sum of the request/response times identical for all CPUs, if I'm understanding correctly.
- kens 5y agoYou mentioned a document with a detailed description of the internals of the Xbox 360 CPU. I don't suppose that document is available to the public?
- brucedawson 5y agoSorry, I've never seen a non-NDA document with full details. Some information was released but it was a bit spotty.
- marcan_42 5y agoI was thinking bidirectional ring bus in my model; indeed if it were unidirectional you'd end up with the same result for all CPUs. FWIW, the Cell used a bidirectional ring bus network, and it's of the same generation and happens to share technology heritage with the XCPU... (very similar PowerPC core) :-)