Lexichip3 Wcs Test (3); Lexichip3 Interrupt Timer Test (4) - Lexicon MPX 110 Service Manual

patterns: 55 hex (01010101 binary), AA hex (10101010 binary) & FF hex (11111111 binary).
Before the test is executed, a test code will be put out on the Binary LED's. The code is:
Edit Bypass
O O
MSB
If a failure occurs, the Clip (red) headroom LED's will be turned on in addition to the binary code, and the
CPU will attempt to continuously loop the test for troubleshooting purposes.
If the BYPASS button is pressed, the failure is ignored and the next test will be executed.

LEXICHIP3 WCS TEST (3)

This test will check the RAM program memory space ( writeable control store) of the Lexichip3. The WCS
(memory space) is first filled with the value 55 hex (01010101 binary), then each memory location is read to
see if it contains 55. If 55 is in the memory location, the location is filled with AA hex (10101010 binary), and
the next location is processed. Once the RAM has been checked for 55's and filled with AA's, the process is
then repeated checking for AA's and storing 0's into memory. Following this test an Address test is
performed to verify all the address lines are active. Finally, the memory is checked for 0's.
Before the test is executed, a test code will be displayed on the Binary LED's. The code is:
Edit Bypass
O O
MSB
If a failure occurs, the Clip (red) headroom LED's will be turned on in addition to the binary code.
If the BYPASS button is pressed, the failure is ignored and the next test will be executed.
If the TAP button is pressed, the CPU will attempt to go into a mode where it can execute the test
continuously.

LEXICHIP3 INTERRUPT TIMER TEST (4)

The Interrupt Timer test will verify that the interrupt (INT/) is working and occurring at the proper intervals.
The Lexichip3 will provide the MPX 110 with the interrupt (INT/) to the Z80's maskable interrupt line. The
interrupt test will be run for a period of time that allows 20 interrupts to occur. A count of the interrupts is
kept and compared for overshoot and undershoot. Greater than 21 interrupts means the interrupt is too
short and less than 19 interrupts means it's too long.
Before the test is executed, a test code will be put out on the Binary LED's. The code is:
Edit Bypass
O O
MSB
If a failure occurs, the Clip (red) headroom LED's will be turned on in addition to the binary code.
If the BYPASS button is pressed, the failure is ignored and the next test will be executed.
If the TAP button is pressed, the CPU will attempt to go into a mode where it can execute the test
continuously.
Store Tap
l
O
LSB
Store Tap
l
O
LSB
Store Tap
l
O
LSB
Lexicon
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