READ
Reads the sixteen bit value from the location pointed to by R0. Data is returned in R2 (LSB) and R3 (MSB). This routine should always work regardless of calls to WEN and WDS, but it should not be called immediately following a call to PREN. Valid address range for R0 is 0 to 63.
WEN
Enable writing. This operation must be performed before a write may be issued. This applies to both the 93C46 and 93CS46. Unlike PREN below, writing should remain enabled until a WDS is called.
WRITE
Writes the sixteen bit data in R2 (LSB) and R3 (MSB) to the location pointed to by R0. Writing must have been enabled using WEN. For the 93CS46, if this location is "protected", no data will be written, regardless of calls to WEN and WDS. Writing takes a considerable length of time (milliseconds). This routine just waits for it to finish before returning... hope you don't have any polled I/O you wanted to keep doing!
WDS
Disable writing. This disables write operations. It applies to both the 93C46 and 93CS46 chips. It is advisable to disable writing if no additional write operations are expected soon. In this state, the chip may have better resistance to accidental data loss due to problems on the power supply, noise on signal lines, etc.
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