Lexicon MPX 500, Руководство по обслуживанию

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MPX 500 Service Manual
5-2
The table below displays the Power Up Diagnostic test code which the front panel will display before the
tests are executed.
Test
No. Test
Name Bypas
s
Store Tap
1 ROM 0 0 1
2 SRAM 0 1 0
3 WCS 0 1 1
4 INT 1 0 0
5 ADF 1 0 1
6 EEPROM 1 1 0
0 = OFF
1 = ON
Test Descriptions
#1 ROM Test :
The ROM checksum, which is a byte size value, is located in the last location of each Bank. The test adds
the contents of the entire ROM including the check sum byte. The result should equal a 0 for the test to
pass.
#2 SRAM Test:
This test will verify the entire contents of the SRAM. The test first writes 00hex (000000000 binary) to all of
the memory locations, and then verifies this by reading back all the memory locations. The test will also
write/read the following patterns: 55hex (01010101 binary), AAhex (10101010 binary), and FFhex
(11111111 binary).
If what is written to all locations is read back, the test will pass.
#3 WCS Test:
This test will verify the program memory space of the Lexichip 3. The Ram (memory space) is first filled with
the value 55hex (01010101 binary), then each memory location is read back to confirm it contains the 55.
The memory space is then filled with AAhex (10101010 binary) and the memory is read back again. The
final test is the memory is filled with 0’s. If what is written to all locations is read back, the test will pass.
#4 INT Test:
This test will verify that the Lexichip 3 interrupt (INT/) is working and occurring at the proper time intervals.
The Lexichip 3 does this by providing this signal to the Z80’s maskable interrupt line. If the Z80 sees the
signal at the proper times the test will pass.
#5 ADF Test:
This test will verify that the Audio Data File in the Lexichip 3 is working properly. The Lexichip 3 Audio Data
File (ADF) is a fast synchronous 128-word SRAM that provides audio data buffering and storage for
external memory references, Serial I/O and the Host-to-Lexichip data port. ADF locations also function as
ARU Registers and as scratchpad memory.
#6 EEPROM Test:
This test will verify the functions of the EEPROM on the MPX 500.
First the test will verify that the EEPROM has been initialized properly. This is done by storing the software
version of the EPROM in the first five bytes of the EEPROM. Then the stored value is verified if correct