MPX G2 Service Manual
5-14
If the test failed because the MIDI Input didn't received any data, the display reads:
MIDI Test Failed
Rec Tim (done)
If the test failed because the MIDI Output didn't transmit any data, the display reads:
MIDI Test Failed
Tran Tim (done)
If the test failed because the MIDI Input received bad or wrong data, the display reads:
MIDI Test Failed
Bad Data (done)
DRAM Test
This test will put the Lexichip 2 (U85) into a mode that will allow the Z80 processor (U90) to read and write
to the (5) 256K X 4 DRAM’s (U78-82) through the Lexichip. To actually test the DRAMs, the Z80 processor
performs two tests: a data test and an address test. During the data test the Z80 processor writes "AAAAA"
(hex) (10101010101010101010) into all of the memory locations then reads them back to check them. It
repeats the process with "55555" (10100101010101010101). For the address test, the Z80 processor
writes a count into the memory then reads it back (i.e. 00000000000000000001, 00000000000000000010,
00000000000000000011).
At the Functions Tests menu turn the Encoder until the display reads the following:
Diags: Tests
< DRAM
Next press the STORE button and release. After the STORE button is pressed, the test is executed and
display will read the following during the test:
DRAM Test
Running
During the execution of the DRAM Test, a chase pattern is first displayed on the leftmost 7 segment display
followed by moving to the middle and then to the rightmost 7 segment display. This feature was added to let
the operator know that the test is running and has not crashed.
If the test passed (after 2 ½ minutes), the display reads:
DRAM Test
Passed (done)
If the test failed, the display reads:
DRAM Test
Failed (done)
When the test is finished, the STORE button LED is flashing. The OPTIONS button LED is lit.
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