作者BF3716 (JS)
看板Grad-ProbAsk
标题Re: [理工] 计算机组织与系统
时间Fri Apr 17 16:50:19 2009
We want to compare the maximum bandwidth for a synchronous and asynchronous bus.
The synchronous bus has a clock cycle time of 50ns,and each bus transmission
takes 1 clock.The asynchronous bus requires 40 ns per handshake.The data portion
of both buses is 32 bits wide.Find the bandwidth for each bus when performing
one-word reads from a 220-ns memory.
[同步]
1. 传送位址给记忆体: 50ns
2. 记忆体存取: 220ns
3. 传送资料: 50ns
传送one-word 合计需要320ns
one-word 4bytes
汇流排频宽: ---------- = --------- = 12.5 MB/Sec
320ns 320ns
[非同步] 交握协定具有7个step
1. step1 : 40ns
2. step234 : max(3*40ns,220ns) = 220ns
3. step5 : 40ns
4. step6 : 40ns
5. step7 : 40ns
传送one-word 合计需要380ns
one-word 4bytes
汇流排频宽: ---------- = --------- = 10.52 MB/Sec
380ns 380ns
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1F：推 sak1346:原PO计组神 快拜 04/17 16:52
2F：推 newfantasy:推神手~帮我看一下18068^^ 04/17 17:08
3F：推 beautyanzi:step234 : max(3*40ns,220ns) = 220ns ，有写错吗? 04/17 21:24
4F：→ beautyanzi:3*40ns=? 04/17 21:25
5F：→ Westind:感谢 又懂一题了 04/17 22:03
6F：→ BF3716:Step2+Step3+Step4 跟记忆体存取会并行，要取比较久的时间 04/17 22:44
7F：→ BF3716:可以参考交握协定的时序图 04/17 22:45