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| A Simple Switch Operated 2864 Eeprom Programmer. [schematics] |
Based on the SALT EEPROM Programmer by Walter J. Bankes.
An EEPROM Programmer so simple you must set each address and each byte of data on some switches to program each location in the memory chip. It is a slow process, but you'll be sure to learn the difference between addresses and data.
Connect pin #26 to +5 volts to allow compability with the 6264 SRAM part. RAM can then be demonstrated (tested) using the same circuit. The READ and WRITE normally open momentary push buttons are pulled up through 3.3K resistors. 13 address switches are used; A0..A12 plus a low CS [Chip Select]. The 8 switches for data input must be placed in the '0' (low) position for data output (read). The eight LEDs will indicate '1' (high) by being lit. This is accomplished using a low current (max 2 mA) LED.
All switches in the picture is in the low ['0'] position; i.e., the address selected is 0x000h, while the data byte is set to 0x00h (which also is the correct setting to read the data stored at address 0x000h on the chip by pressing the green push button).
2864, 2865, and even 6264 can be programmed using this simple device, and chips like these can often be ripped off old discarded surplus material.
Jens Laland, Bryne