Digital Equipment VAXstation I Service Manual page 72

MAINTENANCE
Table 3·8: VCBOl Diagnostic Tests (continued)
+. - . -+- - • - - - - - - - •• - - • - - - - - • - • - - - • - - - - - - • - - - - • - • - - - - - - - - - - • - - - ••
-+
iTEST! DESCRIPTION
I
+- - - ·+· - - - - - - - - - - - - - - - - - - - - - - - - - •.. - • - - - - - .• - • - - • - . - - - - • - - ••. - • ·+
10 MOUSE COUNTER TEST -- Using exetrnal loopback connectors,
the CSR, and UART B, this test forces the mouse X/Y
counters to count up and down.
11 MEMORY REFRESH TEST ·· Verifies the operation of the
VCBOl's memory refresh circuitry.
12 ODD/EVEN PIXEL GENERATOR ·- Verifies the video shift
registers (requires visual verification). Odd pixels
should be displayed on the top-half of the screen and even
pixels on the bottom-half. If half or all of the screen
is blank, then a problem exists in either or both shift
registers.
13
14
MOUSE AND KEYBOARD INTERACTIVE TEST -· Displays the
pointer icon, and a test pattern comprising a square in
each corner of the screen. The test also initializes the
keyboard. The icon should reflect mouse movement, and a
check is made to see if the returned mouse coordinates
compare to the coordinates of the squares displayed on the
screen. Any combination of depressed mouse buttons should
display the equivalent octal code, and the code for any
depressed keyboard key should be displayed.
ALIGNMENT PATTERN
alignment pattern.
GENERATOR -- Displays the
monitor
+·. - ·+- - ....... - - - - . - - .. - .. - . - - . - - - - ..... - - - - - . - •.. - . - ...•. - . - - -+
3-18