!lm12
!rm75
EPROM Blaster Defined......................Bob Sander-Cederlof

Several readers have asked what an EPROM blaster is.  This is a device, more commonly called an EPROM programmer or writer or burner, which writes data into an EPROM.  The EPSON interface has an EPROM device on it, called a "2708", which can hold 1024 bytes of data or program.  (Only the first 256 bytes are actually used by EPSON.)  A company called Apparat advertises a card for the Apple II which will write (burn, program, blast,...) stuff into a 2708.  They call their board the "Blaster".

Mountain Computer makes the ROMWRITER board for the Apple.  This board can only burn single-voltage 2716 EPROMs, the Apparat board can burn 2708s, 2716s, and 2732s, whether single or multiple voltages.  And ROMWRITER costs almost twice as much.

Maybe you are asking, "What on earth is an EPROM, anyway?"  EPROM stands for "Erasable Programmable Read Only Memory".  The "memory" part is easy:  each EPROM can hold a large number of bytes of data or program.  A 2708 holds 1024 bytes, 2716 holds 2048 bytes, and a 2732 holds 4096 bytes.

"Read Only" means that once the bytes are recorded, they cannot be changed.  They are permanent, even if power is removed.  "Programmable" means that you and I can, with a burner or blaster", record the bytes; the chip comes un-recorded from the factory.  Non-programmable ROMs are recorded during manufacturing.

"Erasable" means that you can erase what you have recorded and re-use the chip.  An ultraviolet lamp is used to erase the contents; I bought a $75 EPROM Eraser from Logical Devices in Florida for the job.  Maintaining the level of confusion, still other letters can be added to the acronym:  EEPROMs are "Electrically" erasable; EAROMs are too (I don't know the difference between the two, if any).
