
Host Interface
4.5 Timing Rule
Table 4.75 Timing specifications (1 of 3)
No. | Name | Standard | Timing specification |
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1 | Arbitration | 2.4 µs min. | The minimum wait period between the time the |
| Delay |
| SCSI device sends a BSY signal and the time the |
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| value on the data bus for determining the |
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| priority of bus use is judged in the |
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| ARBITRATION phase. A maximum time is not |
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| defined. |
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2 | Assertion Period | 90 ns min. | Minimum pulse width of an ACK signal sent by |
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| INIT and an REQ signal sent by TARG for |
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| synchronous data transfer. |
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3 | Bus Clear Delay | 800 ns max. | Maximum allowable period between the time |
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| either of the following events occurs and the |
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| time the SCSI device stops driving all bus |
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| signals. |
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| (1) Detection of the BUS FREE phase (when |
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| both BSY and SEL signal become false |
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| during Bus Settle Delay). |
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| Note: |
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| Maximum allowable period between |
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| the time both BSY and SEL signal |
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| became false and the time the bus is |
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| released is 1,200 ns. |
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| An SCSI device that requires a period |
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| longer than Bus Settle Delay for the |
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| detection of the BUS FREE phase |
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| must release the bus within (Bus Clear |
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| Delay) minus (Bus Settle Delay excess |
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| time). |
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| (2) Another SCSI device asserts the SEL signal |
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| during an ARBITRATION phase. |
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| (3) The RST signal becomes true (RESET |
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| condition). |
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4 | Bus Free Delay | 800 ns min. | Minimum wait period between the time the |
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| SCSI device detects a BUS FREE phase and the |
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| time it sends a BSY signal to initiate an |
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| ARBITRATION phase. |
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5 | Bus Set Delay | 1.8 µs max. | Maximum allowable period between the time an |
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| SCSI device detects a BUS FREE phase and the |
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| time it sends BSY and SCSI ID signals to |
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| initiate an ARBITRATION phase. |
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