HP 8112A Operating, Programming And Servicing Manual page 287

Changing the ROM
Keyboard
Table 1 0.7-5. ROM U40 signatures
Data probe Connect Start/Stop probes to Ul2 pin:
U140 pin
1 1
12
13
15
16
17
18
19
If the ROM is changed, the data saved in the RAM has to be made
compatible with the new ROM . This can be done by setting the HP
8 1 1 2A to RCLO and turning the instrument off and on again.
If the instrument becomes totally inoperable switch it off and
disconnect the RAM back-up battery
for at least 30 seconds. This will destroy the stored RAM data.
Re-connect the RAM back-up battery and switch the instrument on.
The Standard Parameter Set is now loaded into the RAM .
The keyboard can be checked using signature analysis:
1 . Set the microprocessor to free-run as described in "Free Running
Signature Analysis" and connect the signature analyzer probes as
given in Table 10.7-2.
2. Verify the reading at microprocessor +5 V supply is is 0003 . If it
is not , the microprocessor is not free-running.
3. Connect the data probe to TP7, on the microprocessor board A3,
and check the signature obtained when each key is pressed against
Table 10. 7-6.
Servicing the Microprocessor and Front-panel 1 0.7-17
7 10
9
P191 3HA1 5808 U88F
618A 3HFH 60F5 70CU
OlUP 03A9 452P 6PC3
H862 34PH 773 3 3C35
61Cl C3FO 41PU U623
F8H8 73UF 3HOH A4HF
5U29 FP6U P912 2C09
P3F3 A795 8PF7 2125
(
by removing W2 jumper
11 12
OA6P
UPlC
95FH
4102
AHUA
06AF
7000
4 C7P
)