[CS61C FA20] Lecture 19.7 - Single-Cycle CPU Datapath II: Summary — Transcript

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1. 0:01[Music]
2. 0:10and welcome back to risk 5 cpu design
3. 0:13in this little mini module we don't
4. 0:16really have to do
5. 0:17anything else except to congratulate
6. 0:19ourselves
7. 0:20what do we congratulate ourselves on
8. 0:22well we have just
9. 0:23designed a complete data path that can
10. 0:26execute every single one
11. 0:28of the rv32i instructions from
12. 0:32risk five isa that's quite amazing that
13. 0:36enables us to execute us any c program
14. 0:40that we can compile into this file
15. 0:42assembly
16. 0:43on our custom processor that's quite an
17. 0:46accomplishment
18. 0:49so every single one of these
19. 0:50instructions from the risk 5
20. 0:53green sheet can be executed there are
21. 0:55two of them that are left to deal with
22. 0:56os support but we really don't need them
23. 0:59for
24. 1:00compiling programs
25. 1:04so in a very quick summary we have
26. 1:06designed a complete data path
27. 1:08it is capable executing all rx5
28. 1:11instructions
29. 1:12in a single cycle each now keep in mind
30. 1:16that we have designed one version of a
31. 1:19hardware
32. 1:20there can be multiple different
33. 1:22implementations
34. 1:23of risk 5 data path
35. 1:27in hours not every single instruction
36. 1:29was lighting up
37. 1:30every element in the data path every
38. 1:33unit in a data path
39. 1:35but every element or every unit
40. 1:38was lit up somehow so every single one
41. 1:40of them had a purpose
42. 1:42we also have seen that the execution can
43. 1:45be
44. 1:46generally separated into separate
45. 1:49phases of execution so we had
46. 1:52instruction fetch instruction decode
47. 1:55with register access execute phase
48. 1:58memory access phase and write back
49. 2:02and what we have seen that not every
50. 2:04single instruction
51. 2:07is active in every single one of these
52. 2:08phases
53. 2:10some of them may be active in just four
54. 2:12out of five phases
55. 2:15now important thing that we have been
56. 2:18touching
57. 2:19on is the this controller that was
58. 2:22configuring the data path
59. 2:23to execute the instructions properly
60. 2:27we have talked about what kind of
61. 2:28signals we would like to get out of that
62. 2:30control unit
63. 2:31but we haven't spent much time or any
64. 2:35time
65. 2:35on designing the control unit so
66. 2:39that's what we're going to do next see
67. 2:41you then