Atari Super Breakout faults and diagnostics
by Grant Searle 2009

Last update: 7th February 2009

Some notes to help to get you going...


Note: on the super breakout board there is a reset switch which is not very obvious. On the above picture, it is the circular object at the top-left, immediately to the right of the blue capacitor.

The following screenshots show the board running on a monochrome green monitor. The arcade machine uses a white phosphor monitor (ie. a normal black and white display) with coloured plastic strips covering areas of the screen to mimic a colour display.

Please note that these are REAL screenshots of actual faults.

Screen display Notes
Test switch = OFF
This is a typical display of "attract mode" when the game is working properly.
Test switch = ON
Here is the diagnostics screen (ie. when the test switch is turned on) for a fully working machine. The hex digits at the bottom of the screen will change between 00 and FF when the paddle control is turned.
Test switch = ON
Here is a typical diagnostics screen when there is a fault with one or more of the 8 RAM chips (labelled 2102 near the middle of the board). When this happens you are supposed to hear a set of 8 beeps (some low, some high) to indicate which RAM "bits" are good or bad. However, I have tried this with various self-induced RAM faults and I don't always get the beeps, and when I do, not all faulty bits are always identified.
The test routine is able to run purely in ROM, so faulty RAM would still allow it to run.
Depending on the RAM fault, you will probably get different characters appearing, but the overall pattern should resemble something like what you see here. The diagnostics part of the ROM is able to run without RAM, so as long as the ROMs and CPU (and associated circuitry are functioning) then you will get this when there is faulty RAM.
Test switch = OFF or ON
A garbled (normally steady) screen indicates the CPU is not running the program. This could be due to several reasons, such as a fault with the CPU or the ROMs. A short on any of the address or data lines will also cause the CPU to crash. The ROMs on the board are located on row 1. Issue 3 boards have 10 small PROMS (4 bit), and issue 4 boards have 3 larger PROMS (8 bit) instead.

The display is totally random so you will see a similar display, but with different characters in different positions, but the overall effect is the same.
The ball display circuitry is independent of the character display, and is overlayed on top of the character display.
As a result, if you watch the faulty screen for a while, you may see some small blocks (the 3 balls) randomly jumping about the screen.
The PROMs are selected using a PROM at E2 and a 10-way selector at F2. A fault on these would prevent the ROMs being made active. The address bus is buffered by ICs A2, B2 and C2, so these should be checked as well.

Test switch = OFF
A partly drawn screen, flashing, indicates a problem with the reset circuitry. There is a built-in watchdog reset on the board, which will automatically reset the CPU if it has crashed. The reset occurs when the watchdog timer reaches the end of it's count. During correct program operation, the program will reset the watchdog counter at regular intervals to prevent it resetting the CPU. This also ensures correct resetting of the CPU on power-up.
Test switch = OFF
A representation of the game can be seen, but incorrect characters displayed indicates a fault with the address lines reaching the character ROMs. The character ROM is split over 2 PROMS, so, if one half of the characters is correct, but the other half is incorrect then there is a fault with one of the character PROMS.
Test switch = OFF
A representation of the game can be seen, but here we have horizontal lines. This indicates either a fault with one or more data lines from the character PROMs (ie. faulty PROM) or it could be a fault with the 74166 IC used to serialise the data from the PROM to the display.

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