Troubleshooting
2-25
Test 103.5 – Digital input
Pass/Fail
Defective digital input port.
This test only veriÞes that the digital input signal is pulled high at PB8 of the micropro-
cessor (U626). Success of this test does not guarantee complete functionality of the in-
put port.
IEEE-488 bus tests
The IEEE-488 interface in the model 2001 consists of the 9914 GPIB chip (U622) and the
75160 (U621) and 75161 (U623) bus drivers. The 75160 buffers the data lines (DIO1-
DIO8), and the 75161 buffers the bus handshake lines and other control signals. The cir-
cuitry to test these components is contained in the 5064 ASIC (U618).
Test 104.1 – Handshake
Pass/Fail
Cannot properly perform an IEEE-488 handshake.
Circuitry in the 5064 (U618) is set up to simulate an IEEE-488 handshake. Bytes are
written to the 9914 (U622) Data Out register and the interrupt status register is checked
to verify that a Byte-Out handshake is completed.
These tests verify the basic functionality of the 9914, 75161 and the handshake portion
of the ASIC (Signals BNRFD, BNDAC, and BDAV).
U618, U622 and U623.
Test 104.2 – Data
Pass/Fail
Cannot properly write data to the 9914.
For this test, bytes are written to the 9914 Data Out register (U622) to drive and release
bus line DIO1. The state of this signal is veriÞed at the 68302 (U626) through PB0
(BITB1). This test veriÞes the basic functionality of the 9914 and 75160 (U621).
U612 and U622.
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