generate a vector would assert one of these lines when it required to interrupt,
expansion cards availing themselves of this facility should provide it via links so
that the particular line can be selected by the user.
Line 63, /PWRF.
Powerfail warning. This line is to be taken low 100mS before the power rails
drop by more than 5% and held low until 100mS after the power on reset. For use by
backup memory etc. Optional signal which would be provided by the power supply
circuitry if implemented.
Line 64, AUX PWR.
An auxilary +5 volt supply for the use of backup devices. Absolute maximum
current when the main power supplies are off is 100mA. Implementation is optional.
65 66, NDEF1 NDEF2.
Not to be defined. These are lines for users to allocate as they require,
are only two restrictions and one provision.
a)TTL levels only, ie no voltage greater than 5 volts and no voltage less than 0
b) No transition until 100nS after the previous transistion, ie don’t put a 16MHz
clock on this line.
c) A link must be provided to disable the use of NDEF 1,2.
Line 67, GND.
An additional ground line to separate the power lines from the rest of the
68,69, –5 volt supply.
70,71, –12 volt supply.
Line 72, Keyway
73,74, +12 volt supply.
75,76,77,78, +5 volt supply.
Daisy chains :
|SLOT 2||SLOT 1||SLOT 0|
|Expansion cards||Bus Master|
|X = Cut of bus track|
|I = Link between tracks|