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Serial EEPROM Programmer

Very useful software for reading and writing 93Cxx, 24Cxx, and 24Wxx series EEPROMs. Needs only a very simple hardware, connects to parallel or serial port.

It is just a simple software for testing and programming serial EEPROMs using the PC parallel or serial port. Supply voltage +5V is taken directly from the port. Warning - some parallel ports can't be used this way. The schematics and a description is included in the online help.

Parallel port version

Parallel port version schematics

It is an excellent idea to include protective resistors (not shown in the above schematics) to protect the parallel port in case of a defective EEPROM. It is definitely recommended if you have the LPT integrated on your mainboard. Reasonable values are 470R for the power supply pins (D0 and D5), and 1k5 for the rest of them (D1, D3, D4).

Serial port version

Serial port version schematics

The programmer hardware - a DIL16 socket (or two DIL8's), two low-power LEDs, and a few resistors, easily fit into a Cannon 25 connector cover. Don't use a metallized cover, if the socket pins run through it.

One half of the socket is for 93Cxx EEPROMs, the other half is for 24Cxx and 24Wxx. The green LED is on while the control software runs, the red LED is on during reading and writing, when the supply voltage is applied to the device.


The software currently supports these devices: 93C46/56/57/66/76/86, 24C01/02/04/08/16/32/64/128/256. Software is designed according to specifications by Atmel and ST. It has been tested with 93C46/56/66 and 24C16 - I did not have other ones available; however, I expect them to work too. The software does not use any special modes like Current Address Read, Sequential Read, Multibyte Write, or Page Write. It uses only the basic modes - Random Address Read, Byte Write. They are not as fast as the special ones; however, they should work with any EEPROM by any manufacturer. (I came across a series of ST24C16 which would not allow any writing in Multibyte Write mode. Older series seem to work fine.)

Download & Links

The software is constantly being updated, new devices and features are being added.
Version 1.3 dated November 1, 1999 - download here.

Author: Zdenek Janovsky
English translation: Joe Hlavac
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