5

MCECC

DRAM Control Register

The bit assignments for the DRAM Control Register are:

ADR/SIZ

 

 

1st $FFF43018/2nd $FFF43118 (8-bits)

 

 

 

 

 

 

 

 

 

 

 

BIT

31

30

 

29

28

27

26

25

24

 

 

 

 

 

 

 

 

 

 

NAME

BAD23

BAD22

 

RWB5

SWAIT

RWB3

NCEIEN

NCEBEN

RAMEN

 

 

 

 

 

 

 

 

 

 

OPER

R/W

R/W

 

R/W

R/W

R/W

R/W

R

R/W

 

 

 

 

 

 

 

 

 

 

RESET

0 PLS

0 PLS

 

0 PLS

0 PLS

0 PLS

0 PLS

0 PLS

0 PLS

 

 

 

 

 

 

 

 

 

 

RAMEN RAM Enable. This control bit is used to enable the local bus to perform read/write accesses to the memory. Accesses are enabled when this bit is set and are disabled when this bit is cleared. This bit should only be set after BAD31-BAD22 have been initialized.

Difference from MEMC040: none.

NCEBEN Setting the NCEBEN control bit enables the MCECC pair to assert TEA* when a non-correctable error occurs during a local bus access to memory. In some cases setting NCEBEN causes DRAM accesses to be delayed by one clock. This delay is incurred when the access is a local bus (or scrub) read and the FSTRD bit is set.

Difference from MEMC040: bit = PAREN for MEMC040; bit = NCEBEN for MCECC (both accomplish basically the same thing, enabling TEA assertion for non- correctable errors).

NCEIEN When NCEIEN is set, the logging of a non-correctable error causes the INT signal pin to pulse true. Note that NCEIEN has no effect on DRAM access time.

Difference from MEMC040: bit = PARINT for

MEMC040; bit = NCEIEN for MCECC.

RWB3 Read/Write Bit 3 is a general purpose read/write bit

5-18

Computer Group Literature Center Web Site

Page 308
Image 308
Motorola MVME172 manual Bit assignments for the Dram Control Register are