1-10  General Information 
Self-Test 
During installation you may wish to check the electrical performance of the drive. The drive 
can 
be 
checked with or without a disc installed. To conduct the self-test, follow  this proce-
dure: 
1. 
Remove the front cover of the 9895A, thereby exposing two toggle switches 
and 
an 
LED 
display 
on 
the front edge of the controller (see Figure 1-4). 
2. 
Press 
and 
release the right-hand toggle switch.  The LED's should now start blinking, 
indicating that the self-test routine has begun. 
3.  The routine should terminate with only the right-most 
LED 
lit. 
Any other result indi-
cates a  failure.  Try running the self-test several times to verify pass or failure.  This 
self-test verifies operation 
of: 
a.  HP-IB interface chip (PHI), 
b. 
Read-only memory, 
c. 
Z80 processor, 
d.  Random access memory, 
e.  Serializer / deserializer, 
f. 
Encoder, 
g. 
Decoder, 
h.  Stepping circuit and mechanism, 
i.  Rotational timing 
(if 
disc installed). 
If the drive fails self-test, turn to the troubleshooting section of Chapter 3. 
A more elaborate test, the 
read/write 
self-test, is run using the following procedure: 
1. 
Install a write enabled, formatted, scratch disc in each drive. 
2. 
Press 
and 
hold the left-hand switch. 
3.  While holding the left-hand switch, press 
and 
release the right-hand switch. 
4. 
Release the left-hand switch. 
Read/write 
self-test should now start. 
This routine writes 
on 
the disc 
and 
then reads back,  comparing what it  read with  what it 
wrote. 
It 
checks the 
read/write 
circuitry 
and 
the CRC generator / checker, as well as every-
thing checked by the previous routine. 
A final check, the read-only self-test, may 
be 
run using the following procedure: 
1.  Install a formatted scratch disc in all drives. 
2. 
Press 
and 
hold the right-hand switch.