Service manual

48
In the VERY crude circuit shown here you must first set the binary location code on
switches A0 to A10. Then set the binary data on switches D0 to D7. Close S1; poke the
“PROG” button for an instant (can you guess 50mS ?); open S1. It might work!
For a typical 2716, the following conditions must exist during programming mode: Vcc
must be at +5v; Vpp must be at +26v; Program (PGM) at 0v; the required contents present
on the output pins and the location code on the input pins. Pulsing PGM to +5v for 50
milliseconds burns the data present on D0 to D7 into the location addressed by A0 to A10.
Because there is such a wide variation of programming parameters between even Eproms
bearing identical numbers but from different manufacturers, this book will not attempt to
delve further into methods of programming. It already forms the subject of several books
from each manufacturer, which should be consulted according to the specific type that you
wish to program. If you buy a comprehensive programming unit and follow its instructions
carefully, you should have little difficulty in programming most Eproms without problem.
WARNING Incorrect programming methods can cause an Eprom to become
EXTREMELY HOT. The publishers accept no responsibility for damage or injury caused
by careless or uneducated use of information printed in this book. If in doubt seek expert
advice!