Commodore 1581 - Appendix F: Serial Interface Information

APPENDIX F
SERIAL INTERFACE INFORMATION
The Serial Interface consists of two 6-pin DIN Female Connectors
on each drive. The second connector is for daisy chaining to other
drives and/or peripherals. The voltage interface is a serial interface at
TIL levels.
There are three types of operation over a serial bus—Control,
Talk, and Listen. The host is the controller and initiates all protocol on
the serial bus. The host requests the peripheral to listen or talk (if the
peripheral is capable of talking as disk drive). All devices connected to
the serial bus receive data transmitted over the bus. To allow the host
to route its data to an intended destination, each device has a bus
address (known as device number). Disk drive's device addresses are
normally 8-11.
Data and control signals as follows:
Pin No.
Pinl
Pin 2
Pin 3
Pin 4
Pin 5
Pin 6
Signal Direction
SRQ in/out
(Service
Request)
GND
(Ground)
ATN in
(Attention)
CLK in/out
(Clock)
DATA in/out
RESET
Description
Used by fast serial bus as a bi-
direction fast clock line. Unused by
the slow serial bus.
Logic ground
The host brings this signal low
which then generates an interrupt
on the controller board. The atten
tion sequence is followed by a de
vice address. If the device does not
respond within a preset time the
host will assume the device ad
dressed is not on the bus.
This signal is used for timing the
data sent on slow serial bus (soft
ware clocked).
Data on the serial bus is transmit
ted one bit at a time (software tog
gled in slow mode, hardware tog
gled in fast mode).
This line will reset the peripheral
upon host reset.
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