Maintenance

selected by moving the cursor to a point adjacent to the test name and pushing the INPUT push button.

TEST

MEMORY

>DAC

LED

KEY

EXIT

USE SPAN KEYS TO MOVE CURSOR,

PRESS INPUT KEY TO SELECT

Figure 6-2: 1705A Test menu, displayed when Test is the Main menu selection

Memory Test The NOVRAM (Non Volatile Random Access Memory) test is selected from the crt-displayed Test menu by pushing the VIDEO push button. When this test is selected, the crt first displays a message that gives the memory version and copyright dates.

The test then proceeds to check the NOVRAM and the Electrically Eraseable Programmable Memory (EEPROM). The test goes through three steps, each with its own message displayed on the crt starting with:

NONVOLATILE <2444> RAM TEST

Its first action is to write to and read out of memory; during this step there is a message that the microprocessor is:

WRITING AND READING 2444

This test checks that all lines and the NOVRAM are operating correctly. If the microprocessor can not establish Read and Write communications with the NOVRAM (U812), the following message will be displayed on the crt:

ERROR : CANNOT WRITE TO 2444

1705A Spectrum Monitor

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Tektronix 1705A instruction manual Nonvolatile 2444 RAM Test