Apparatus for on-board programming of serial EEPROMS

摘要

A memory module is described which can be programmed with module information, identifying the type and size of the memory module, after completed assembly of the memory module. The memory module includes a plurality of edge connectors for electrically connecting the memory module circuitry external to the memory module, and a plurality of DRAM memory devices electrically connected to corresponding edge connectors for receiving and providing data from and to the external circuitry. The memory module also includes a Serial EEPROM for storing the module information. The Serial EEPROM has a Serial Data pin connected to a first of the edge connectors for providing the module information to the external circuitry. The Serial EEPROM has a Write Control pin for receiving an enabling signal which selectively enables the operation of the Serial EEPROM in Write or Read-Only mode. The memory module further includes interface circuitry which couples the Write Control pin with a second and a third of the edge connectors. The Write Control pin is coupled to the second edge connector, where V_ss is applied, by a circuit element, such as a jumper, suitable for temporarily connecting the Write Control pin to the second edge connector. A resistor couples the Write Control pin to the third edge connector where V_cc is applied.