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Chapter 3 |
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| Pin # | Signal | Description |
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| All Task File operations occur in byte mode on the low order bus |
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| all data transfers are 16 bit using |
| 4 | SDD8 | Secondary Disk Data 8 – Refer to SDD7 on |
| 5 | SDD6 | Secondary Disk Data 6 – Refer to SDD7 on |
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| 6 | SDD9 | Secondary Disk Data 9 – Refer to SDD7 on |
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| 7 | SDD5 | Secondary Disk Data 5 – Refer to SDD7 on |
| 8 | SDD10 | Secondary Disk Data 10 – Refer to SDD7 on |
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| 9 | SDD4 | Secondary Disk Data 4 – Refer to SDD7 on |
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| 10 | SDD11 | Secondary Disk Data 11 – Refer to SDD7 on |
| 11 | SDD3 | Secondary Disk Data 3 – Refer to SDD7 on |
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| 12 | SDD12 | Secondary Disk Data 12 – Refer to SDD7 on |
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| 13 | SDD2 | Secondary Disk Data 2 – Refer to SDD7 on |
| 14 | SDD13 | Secondary Disk Data 13 – Refer to SDD7 on |
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| 15 | SDD1 | Secondary Disk Data 1 – Refer to SDD7 on |
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| 16 | SDD14 | Secondary Disk Data 14 – Refer to SDD7 on |
| 17 | SDD0 | Secondary Disk Data 0 – Refer to SDD7 on |
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| 18 | SDD15 | Secondary Disk Data 15 – Refer to SDD7 on |
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| 19 | GND | Ground |
| 20 | NC/Key | Not connected / Key pin plug |
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| 21 | SDREQ | Secondary DMA Request – Used for DMA transfers between host and drive |
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| (direction of transfer controlled by DIOR* and DIOW*). Also used in an |
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| asynchronous mode with SDACK*. Drive asserts SDREQ when ready to |
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| transfer or receive data. |
| 22 | GND | Ground |
| 23 | SDIOW* | Secondary I/O Write Strobe – Strobe signal for write functions. Negative edge |
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| enables data from a register or data port of the drive onto the host data bus. |
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| Positive edge latches data at the host. |
| 24 | GND | Ground |
| 25 | SDIOR* | Secondary I/O Read Strobe – Strobe signal for read functions. Negative edge |
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| enables data from a register or data port of the drive onto the host data bus. |
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| Positive edge latches data at the host. |
| 26 | GND | Ground |
| 27 | SDIORDY | Secondary I/O Channel Ready – When negated extends the host transfer cycle |
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| of any host register access when the drive is not ready to respond to a data |
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| transfer request. High impedance if asserted. |
| 28 | NU | Not used (Pull down to ground through 470 ohm resistor) |
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| 29 | SDDACK* | Secondary DMA Acknowledge – Used by the host to acknowledge data has |
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| been accepted or data is available. Used in response to DMARQ asserted. |
| 30 | GND | Ground |
| 31 | IRQ15 | Interrupt Request 15 – Asserted by drive when it has pending interrupt (PIO |
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| transfer of data to or from the drive to the host). |
| 32 | NC | Not connected |
LittleBoard 550 | Reference Manual | 37 |