Thekeys of Keyboard B"write" on the screen according
tothe white arrowheads on the keyboard (Fig. 15). To form
aninteresting pattern, press "Clear" key, then A2, B2 15
times,B6 once, and then BO. The memory stores up to 130
keyentries or "moves". After 130 moves, the computer auto'
maticallystarts to repeat the pattern. For 129 or fewer moves.
KeyBO must be pressed to start the repeat cycle.
KEYBOARDAKEYBOARD B
faha
Inan
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l
BStudioII
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CLEAR KEY#0
STARTS
COMPUTER
PATTERN
Figure 15.Keyboard "B" Moves Spot According to White
Arrowheadson Panel
"Doodles"Function
Press"Clear" key. Press A1 .Single dot appears on screen at
lowerleft corner. Use keys on Keyboard Bto move spot
accordingto white arrows on panel (Fig. 16). Key B5 leaves a
trailas player "writes" with Keyboard B. Pressing Key BO
leavesno trail. Retrace steps to erase lines already written.
Figure16. In "Doodles", etch asketch electronically with the
"B"keyboard
KeyboardTests
If"Tester I" cartridge is available, use it to isolate keyboard
malfunction.If Tester Iis unavailable, the keyboards can be
testedusing the built-in "Addition" game:
Step1:Punch up "Addition" game (Key A5). Sound switch
mustbe "on".
Step2: When the three-digit number appears on screen,
enteraseries of wrong answers, beginning with A1 .As each
buttonis pressed, the beeper sounds, indicating the particular
buttonis operational. The beeper sounds only during the five
secondsthat the random-order display is on screen. Usually,
theentire keyboard can be checked during the five-second
display.If any key fails to sound, that key is faulty and the
entirekeyboard should be replaced.
am ana
13D
KEY#5START
PLAYERA
ENTERS Q
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\io ni B
o\po
DDD
DDD
a
Studio11 DDDDDDDDDD
<
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CLEARI^
—
—.
—
PLAYERB
]ENTERS
'SUM
Figure17. Using "Addition" to Check Keyboards
"Double-Hit"Keyboard Complaints
Someearly production units (Serial Nos. 37125 and lower)
occasionallyexhibit akeyboard malfunction termed "double-
hit"when Studio II operates in the "Patterns" mode (un-
wanteddots appear on the screen, and the beeper sounds
twicefor only one key entry). The only remedy for double
hitsis keyboard replacement.
CoaxialCable Tests
Thecoaxial cable carries modulated RF from the console
andDC from the power unit. Use an ohmmeter to test the
cablefrom the plug end (Fig. 18). Agood cable measures 5to
*J
J
CABLECONNECTOR
I—/©n—
OHMMETER
N
Z>««">
s~^
I
II
4- ""J
Figure18. Checking Continuity of Co-ax Cable
8