Star Tech Journal

8
STAR*TECH JOURNAL/APRIL 1983
GO'l'l't ,TEB
* "Q*BERT'
SYMPTOMS/POSSIBLE CAUSES
* 8088 MICROPROCESSOR
NOTES
Troubleshooting "Q*Bert"
Foreground on the Gottlieb GG-III Video System is generated on a 16 x 16 pixel
format. Foreground characters can be moved to any point on the CRT with each having
its own priority scheme in relationship to the other foreground characters. The
foreground characters consist of: The word "Q*Bert" on the instruction frame, all
moving characters, the large letters for highest score on the high score table, Q*Bert's
balloon that appears when he collides with an enemy and the level number that is
displayed between levels.
Background is generated on an 8 x 8 pixel format and is behind all foreground with
the exception of a priority switch (when Q*Bert falls off behind the pyramid).
It is no secret that solid state hardware does sometimes become defective. It is for
this reason that the accompanying table of symptom/possible causes can be helpful
when troubleshooting the Gottlieb GG-III Logic Board. A note to remember: This list
has been compiled to assist the technician in troubleshooting the Logic Board. The list
of possible faults is not always definitive.
SYMPTOMS
FOREGROUND
NO FOREGROUND CHARACTERS ON SCREEN
FOREGROUND CHARACTERS DIVIDED HORIZ. AND STACKED ON
TOP OF EACH OTHER
TWO SEPARATE CHARACTERS APPEAR STACKED VERT.
THE WORD "Q•BERT' IS SEPARATED INTO SECTIONS
THE WORD "Q*BERT' APPEARS AS HEX NUMBERS
INCORRECT CHARACTERS APPEAR (I.E., SLICK IN PLACE
OF Q•BERT
FOREGROUND CHARACTERS ARE BLURRY (DISTORTED)
HORIZ. LINES THROUGH FOREGROUND CHARACTERS
UNEVEN MOVEMENT OF CHARACTERS
RIGHT HALF OF CHARACTER APPEARS ON THE LEFT SIDE OF
THE SAME CHARACTER
VERT. LINE ABOVE Q•BERT THAT BLANKS EVERYTHING ABOVE
Q•BERT
FOREGROUND DIVIDED VERT. (MIRROR IMAGE OF SELF)
FOREGROUND FROZEN (NO MOVEMEND
INCORRECT FOREGROUND COLORS
CHARACTERS APPEAR AS COLORED SQUARES
BACIGROUND
NO BACKGROUND CHARACTERS ON SCREEN
INCORRECT LETTERS GENERATED ON THE SCREEN
PURPLE SQUARE APPEARS AT BOTTOM OF LETTERS
DISTORTED LETTERS ON TOP HALF OF THE SCREEN
RANDOM LETTERS FLASHING RANDOMLY ON SCREEN
BACKGROUND CHARACTERS ARE BLURRY (DISTORTED)
JUMBLED BACKGROUND
PYRAMID DIVIDED INTO SEVERAL VERT. SECTIONS
HORIZ. LINES DIVIDE CHARACTERS
GREEN BACKGROUND WHEN Q•BERT IS SMASHED
INCORRECT BACKGROUND COLORS
POSSIBLE CAUSES
D2, E1-2, E2-3, E4, GB, J10,
J12 K11
G17, H10, L12
E1-2, E2-3, E4
SIP 71
J1, J2, KS
E1-2, E2-3, E4, G4, J1,
K1-K3
FS
K10, L7-8
SIP 72, SIP 73, H3, H4
FS
H3
617
E1-2
613,614,615, H12, KS, K10,
082-087
K1-K6, K7-8, L4-5, LS-6,
L6-7 L7-8
POSSIBLE CAUSES
DS, D10, EB, E10-11, E11-12,
E13 66 J7 JS J12
E10-11
L10
D9
D11, E7, EB, E9-10, JS
E10-11, E11-12, E13
E10-11, E11-12, E13
E10-11, E16
611
615
613,614,615, 082-087
8088 Microprocessor Notes
The Intel 8088 microprocessor is a third generation microprocessor with an 8-bit data
bus to memory and to 1/0 (Input/Output). The chip is a standard 40-pin dual inline
package (see Fig. 1) and operates from a single +5vdc power source. The 8088 is
extremely flexible in its application and is well suited for use in the GG-111 System.
The processor has dual operating modes ( minimum and maximum) which is allowed
by dual function pins selected by a strapping pin. The GG-III System utilizes the
minimum mode of operation. In this mode, these dual function pins transfer control
signals directly to memory and 1/0 devices.
The high efficiency of the 8088 is conducive to combining a 16-bit internal bus with
a pipeline architecture allowing instructions to be prefetched during spare bus cycles.
Microprocessors execute a program by repeating the simplified cycle shown on page 9.