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Maintenance— 2440 Service
Table 6-6 (cont)
For tests 1200-1500, the sublevel test number and the numerical suffix in the test label indicate
the page and ROM device the test is run on. For instance, the sublevel test ‘ 1320 ROMO.1-5” is
run on page 5 of 16 possible pages, where page 5 is part of ROMO.1 (U682).
The System Processor drives the System Address Decode circuitry to select the device and page
from the System ROM. U890B provide the ROMO.O-3 chip select signals for selecting the ROM
device accessed, and, if the ROM selected is one of the four paged ROMs, U860 supplies the
page-selecting address bits, PAGE-BIT2 and PAGE-BIT3. Using test 1320 again as an example,
U890B sets ROMO.O LO to select ROM0.1 (U682), and U860 sets Page Bits 3 and 2 to LO (0)
and HI (1), respectively, to select the second address page within the ROM device (the second
page of that device is the 5th page of the 16 pages available for System ROM).
N O T E
T h e p a g e n u m b e r a s s o c ia te d w ith th e s u b le v e l te s t la b e ls a re b a s e d o n v ie w in g th e 1 6-
p a g e m e m o ry a s h a v in g th e fo llo w in g s e q u e n c e : th e firs t fo u r p a g e s (p a g e s 0 -3 ) a re
lo c a te d in th e firs t fo u r 1 6 -K b y te a d d re s s s p a c e s o f R O M O .O -R O M O .3 , re s p e c tiv e ly ; th e
s e c o n d fo u r p a g e s (4 -7 ) in th e s e c o n d fo u r 1 6 -K b y te a d d re s s s p a c e s , re s p e c tiv e ly
;
e tc .
T h a t is w hy, in th e p re v io u s e x a m p le , th e la b e l fo r te s t le v e l 1 3 2 0 is ‘ R O M O . 1 -5
”
w h e re
‘- 5 ’ in d ic a te s th e fifth p a g e . P a g e 5 is th e fifth p a g e fo r th e e n tire p a g e d -S y s te m R O M ;
it is th e s e c o n d p a g e (o r 1 6 -k b y te m e m o ry s p a c e ) fo r U 6 8 2 .
Troubleshooting Procedure:
1. A failed ROM test indicates a defective ROM. Check that the correct ROMs are installed in
the correct sockets.
Check out the supply voltages and the chip select to a failed ROM to verify them.
2. A failure of most or all paged ROM indicates a paging chip select problem. The last condition
is probably not detectable as the System /*P is unable to obtain it operating instructions from
the ROM. The System /iP Kernel test (given in Procedure 8) may be used to check that the
microprocessor is operating and to check the chip-select addressing circuitry for correct
operation.
1100 ROM1
Base page ROM, A12U670
1210 ROMO.O-
1st quarter of A12U680 ( page 0 )
1220 ROMO.0-4
2nd quarter of A12U680 ( page 4 )
1230 ROMO.0-8
3rd quarter of A 12U680 ( page 8 )
1240 ROMO.O-C
4th quarter of A12U680 ( page C )
1310 ROMO.1-1
1 st quarter of A12U682 ( page 1 )
1310 ROMO.1-5
2nd quarter of A12U682 ( page 5 )
6 -5 1
Summary of Contents for 2440
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Page 91: ...Theory of Operation 2440 Service 3 49 Figure 3 5 Simplified CCD architecture ...
Page 120: ...Theory of Operation 2440 Service Figure 3 10 DC Restorer 3 78 ...
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Page 136: ...Theory of Operation 2440 Service Figure 3 15 PWM Regulator and Inverter 3 94 ...
Page 138: ...Theory of Operation 2440 Service Figure 3 16 PWM switching waveforms 3 96 ...
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Page 423: ...2440 Service Figure 9 4b 2440 Block diagram part 2 6330 27 BLOCK DIAGRAM PART 2 ...
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Page 517: ...10 16 R E V J U L 1993 Replaceable Mechanical Parts ...
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