474 Chapter9
Controller Section
Digital Signature Analysis −DSA (8560E)
Digital Signature Analysis −DSA (8560E)
Digital signature analysis (DSA) places microprocessor, A2U1, in a
simplified known state. This simplified state consists of placing a
one-word instruction, MOVE QUICK, (0111 XX10 XXXX XXX0) on the
data bus. The microprocessor cycles through its address range
continually reading the instruction. Perform the following DSA
procedure to test the operation of microprocessor, A2U1:
1. Set the HP 8560E LINE switch off.
2. Move the DSA jumper on J3 (located in the middle of the A2
assembly) from the DISable position to the ENAble position.
3. Remove jumper A2E1. A2E1 is a 16 pin dual-in-line package located
in the middle of the A2 Assembly. Set the HP 8560E LINE switch
on.
4. Use an oscilloscope to confirm that address lines, address strobe, and
chip selects are toggling at proper levels.
5. Use an oscilloscope to check the address line sequencing. The signal
on each line (starting with A1 and ending with A23) should be
one-half the frequency of the previous line.
6. If step 4 reveals problems, microprocessor A2U1 is probably faulty.
7. Set the HP 8560E LINE switch off. Replace jumper A2E1. Move the
DSA jumper from connecting E5 and E6 back to connecting E6 and
E7.
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