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frequency is derived from division of the output signal of a 14.7456 MHz hybrid crystal clock
oscillator.
The Al5 Controller firmware includes extensive diagnostics which are executed whenever the
instrument is powered up or the INSTRUMENT PRESET key is pressed.
The microprocessor executes a self-test routine and indicates the results via LEDs. A memory
failure, microprocessor failure, or Instrument Bus failure can usually be pinpointed to the
failed component using these indicators.
HP-IB
Address
Switch
The position of the address switch on the Al5 Controller
(A15SWl)
determines which HP-IB
address is used by the analyzer when the line power is turned on.
The address switch is preset to 31 (switches Al through A5 pressed up) at the factory. If the
CMOS backup battery has not been discharged, the last HP-IB address used by the analyzer
is active at instrument power-up. If the backup battery is discharged, the analyzer will default
to an HP-IB address of 18 at instrument power-up.
If the address switch is set to any address from 0 to 30, this address will be used as the
read/write address by the analyzer with power on.
Switch A6 is also set in the “up” position (logic 1) at the factory. A6 in this position does a
checksum verification of the two pairs of ROMs on the Al5 Controller as part of the self-test
routine with power.
HP-IB
Signal
Ground
(A25)
The A25 HP-IB Signal Ground assembly provides chassis ground for the HP-IB shield. Pins
12 and 18 through 24 of the HP-IB connector J2 are immediately grounded to the chassis
upon entering the instrument.
Firmware
The firmware for the HP 8566B has been changed several times since its origin. These changes
of firmware have required that U37, U38, U39, and
U40
EPROMs be changed. The following
table lists each of the HP 8566B firmware changes, the firmware date (displayed when the HP
8566B is powered on), the HP part numbers for the EPROMs, and the serial number prefixes
of the HP 8566B that the firmware revision was originally manufactured with.
2
A15