Physics 335 - Microprocessor Labs
Comments and Hints for the 68008 Labs
April 6, 2007
These hints will help you and your TA survive and troubleshoot more easily in the microprocessor
portion of this laboratory. WIRING NEATLY IS CRITICAL TO YOUR SANITY ā TAKE A
LITTLE EXTRA TIME TO WIRE RIGHT AS IT WILL SAVE YOU HEADACHES LATER IN
THE QUARTER
ā¢Before doing any wiring, read page 371 in the lab manual and also the Reminders on p 443.
ā¢A breadboard is provided at the front of the room for your reference which has been wired
through lab 22. Consulting this board may help answer some questions and provide insights
about laying out your own board. Please do not change any of the wiring on this board.
ā¢Most of the chips and components are already installed on the breadboard. Please leave them
in their present positions and leave them on the breadboard at the end of the quarter.
ā¢At the end of the quarter, please remove all of the chips, components and wiring you placed
on the board, leaving only the already installed chips (mentioned above) in place.
ā¢It is sometimes useful to follow the resistor color code for bused signals. This practice helps
prevent mistakes and makes troubleshooting easier. We do not have the ribbon cable men-
tioned in the lab manual (and it turns out itās clumsy to use in this case) but all ten colors
of wire are provided.
ā¢0.1 and 4.7 ĀµF capacitors are provided for decoupling purposes in your parts cabinets. Use
a few 0.1 ĀµF capacitors in the horizontal power bus strips of your breadboard. A 4.7 ĀµF
capacitor is handy near where your power enters the board, but REMEMBER TO WATCH
THE CAPACITOR POLARITY or a smoke genie will appear.
ā¢Some chips in the parts cabinet and breadboards are socketed (for mechanical protection)
either because they are expensive, hard to get, or both. Please leave them socketed.
ā¢Donāt forget to use pull up resistors on all unused inputs of CMOS chips (why?).
ā¢Please do not cut the leads from the board mounted switches too short. Someone may want
to configure their board differently. You can leave the extra wire on the bottom side of the
board. Also, please avoid the temptation to bend tightly or weave the wiring. The wiring
is solid core wire, which is needed for breadboard work, but has a tendency to break if bent
tightly.
ā¢If you find any of the smaller circuit diagrams to be ambiguous, it may help to consult the
āBig Pictureā schematic on pp. 606-607.
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