31 lines
1.2 KiB
Markdown
31 lines
1.2 KiB
Markdown
## Lecture 1 (12:00) - Twos Compliment
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- First field becomes -128
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- Overflow happens when:
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- Both numbers are positive or negative
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- Sign is different to sign of input
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| -128 | 64 | 32 | 16 | 8 | 4 | 2 | 1 | Output |
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|------|----|----|----|---|---|---|---|--------|
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| 0 | 0 | 0 | 0 | 1 | 0 | 1 | 0 | 10 |
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| 1 | 1 | 1 | 1 | 0 | 1 | 0 | 1 | Invert |
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| | | | | | | | 1 | 1 |
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| | | | | | | 1 | | Overflow |
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| 1 | 1 | 1 | 1 | 0 | 1 | 1 | 0 | -10 |
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-10x10 = -10 x (8+2) = (-10 x 8) + (-10 x 2)
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| -128 | 64 | 32 | 16 | 8 | 4 | 2 | 1 | |
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|------|----|----|----|---|---|---|---|------|
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| 1 | 1 | 1 | 1 | 0 | 1 | 1 | 0 | -10 |
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| 1 | 0 | 1 | 1 | 0 | 0 | 0 | 0 | <<< |
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| 1 | 1 | 1 | 1 | 0 | 1 | 1 | 0 | -10 |
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| 1 | 1 | 1 | 0 | 1 | 1 | 0 | 0 | < |
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| 1 | 0 | 1 | 1 | 0 | 0 | 0 | 0 | -80 |
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| 1 | 1 | 1 | 0 | 1 | 1 | 0 | 0 | -20 |
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| 1 | 1 | | | | | | | Overflow |
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| 1 | 0 | 0 | 1 | 1 | 1 | 0 | 0 | -100 |
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