NEC µPD72257 Preliminary User's Manual page 321

External Memory Interface Controller
Bit Bit name
3 PRCHALG
2 PWDM
1 SREF
0 INIT
Function
1 refresh all rows
PRCHALG determines when a row is precharged
0 immediate precharge: row precharged at end of read/write operation
1 delayed precharge: row kept open after read/write operations
PWDM control the power-down mode of the Memory Controller
0 leave power-down mode
1 force power-down mode
SREF controls the SDRAM self-refresh mode
0 leave SDRAM self-refresh mode
1 enter SDRAM self-refresh mode
By use of INIT the Memory Controller can be forced to initialize the SDRAM
0 initialization sequence is complete
1 force SDRAM initialization
This bit is set to "0" automatically once initialization sequence is complete.
Note:
After reset release INIT is set to "1", but is set to "0" after initialization is completed.
Preliminary User's Manual S19203EE1V3UM00
Chapter 9
321