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Firmware on EPROMS: A Key to Apple II Forever

Jul 16, 2015 @ 2:00 pm - 2:45 pm

Most computer equipment contain EPROMs on their circuits: CPUs, printers, interface cards, or peripherals. The EPROM chips contain firmware code to control operation of the device. An EPROM looks like a large IC chip: It is wide, with 24 to 40 pins. There is a small round window in the center of the upper side of the chip, with a microlattice of fine metal wires visible through the clear quartz-glass window. The EPROM chips can be erased and reconfigured by hours of exposure to ultraviolet light, followed by software-controlled “burning” of fresh code. The use of EPROMs allows the periodic upgrading of firmware. In my presentation, EPROMs and related hardware will be shown and discussed. Knowledge about EPROM technology should be shared among Apple II devotees because the EPROMs can go bad after years of service. The firmware code can be stored on floppy disks, and then used to rejuvenate EPROMs that have gone bad. In the long run, spanning future decades, Apple II equipment will survive only if the firmware code on the EPROMs has been preserved on disks; once on disk, the code on could be preserved for indefinite archiving by recopying it to other long-lasting media such as CD-ROMs or flash drives. Apple II users should learn EPROM-burning skills, with the needed hardware, to create fresh copies of the firmware code for themselves and to be shared widely with others.


Jul 16, 2015
2:00 pm - 2:45 pm
Event Category:


Corcoran Hall


Stephen Buggie