EXTERNAL DISK CONNECTOR IDENTIFICATION MODE
An identification mode is provided for reading a 32-bit serial
identification data stream from an external device. To initialize
this mode, the motor must be turned on, then off. See pin 8,
MTRXD* for a discussion of how to turn the motor on and off. The
transition from motor on to motor off reinitializes the serial
shift register.
After initialization, the SELxB* signal should be left in the
inactive state.
Now enter a loop where SELxB* is driven active, read serial input
data on RDY* (pin 1), and drive SELxB* inactive. Repeat this loop
a total of 32 times to read in 32 bits of data. The most significant
bit is received first.
EXTERNAL DISK CONNECTOR DEFINED IDENTIFICATIONS
$0000 0000 - no drive present.
$FFFF FFFF - Amiga standard 3.25 diskette.
$5555 5555 - 48 TPI double-density, double-sided.
As with other peripheral ID's, users should contact Commodore-Amiga
for ID assignment.
The serial input data is active low and must therefore be inverted
to be consistent with the above Table.
EXTERNAL DISK CONNECTOR LIMITATIONS
1. The total cable length, including daisy chaining, must not exceed
1 meter.
2. A maximum of 3 external devices may reside on this interface,
but specific implementations may support fewer external devices.
3. Each device must provide a 1000-0hm pull-up resistor on those
outputs driven by an open-collector device on the Amiga
(pin 8-10, 16-21).
4. The system provides power for only the first external device in the
daisy chains.
- Appendix E 311 -
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