Atari 1200 XL, Field Service Manual

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To enter test, select letter D and RETURN. The screen returns the prompt to enter a test
format. Enter command E and press RETURN. Enter the command letter C and press
RETURN for continuous testing.
Press the command letter R and then RETURN to activate the RAM test. To terminate the test
press the SPACE BAR. NOTE: The RAM test completes its current test before stopping.
RAM TEST
This test verifies the operation of the RAM chips. Press the command letter R and then
RETURN to activate this test. Figure 3-6 illustrates the RAM test screen display when
command letter E is pressed under Display Options. The four digit number in white at the
bottom right of the screen indicates the number of tests completed. A red four digit number
directly above this is used to count the number of failures.
Failures appear as red 1's in this display.
Error Counter
Test Counter
Figure 3-7. RAM Test Screen.
Only the D row is applicable for the 1200XL. Use the information below to identify the
defective RAM.
Each red 1 from matrix row D indicates a failing chip. Use the information_ below to identify
each chip location.
1200XL Home Computer
Field Service Manual 3-8