
IBM3206K0424
Preliminary
IBM Processor for Network Resources
pnr25.chapt04.01
August 14, 2000
The DRAM Controllers (COMET/PAKIT)
Page 187 of 676
26
Disable Zero Address Error 
Detection.
When set to 
‘
1
’
, this bit disables the detection of zero address errors to memory.
25-24
State Information Selection.
These bits control what will be visible on the enstate outputs if COMET/PAKIT are 
selected for observation on the enstate pins.
23
Disable Driving Memory Data 
Nets When Idle
When set to 
‘
1
’
, this bit disables the memory controller from driving the memory data 
nets to 
’
0
’
 when the controller is idle.
22
SDRAM Split ECC
When set to 
‘
1
’
, this bit indicates that the ECC/parity for multiple arrays of memory are 
in separate modules and a slight increase in performance is possible. If this bit is 
‘
0
’
, the 
ECC/parity is in a shared module. If using neither ECC or parity, this bit should be set to 
’
1
’
 for a slight performance increase. This bit applies only when SDRAM is being used.
21
SDRAM Burst Length of 2
When set to 
’
1
’
, this bit indicates that the SDRAM should be driven assuming a burst 
length of two. This bit set to 
’
0
’
 indicates a burst length of one.
20
Drive SRAM Output Enables
When set to 
’
1
’
, this bit allows functional output enables to be driven for SRAMs. When 
set to 
’
0
’
, the output enables are driven active continuously. 
19
Freeze Error Registers
When set to 
’
1
’
, this bit freezes the Memory Address Register and the Syndrome Regis-
ter when a memory error occurs. When this bit is set to 
’
0
’
, the error registers are 
updated whenever an error is encountered. For this bit to have any meaning with single 
bit errors, bit 18 must also be a 
’
1
’
. 
18
Latch Error Registers on Single 
Bit Errors
When set to 
’
1
’
, this bit allows error data to be latched into the Memory Error Address 
Register and the Syndrome Register when a single bit errors occurs. When this bit is 
set to 
’
0
’
, single bits errors do not latch data into the error registers. 
17
Enable ECC or Parity
This bit set to 
’
1
’
 enables ECC detection/correction or parity error detection.
16
SRAM Byte Enables for Writes 
Only
When set to 
’
1
’
, this bit' causes byte enables to only be driven on writes to SRAM. The 
enables are driven inactive for reads. If the bit is set to 
’
0
’
, the byte enables are valid on 
both reads and writes. 
15
Disable SDRAM Overlapped 
Bank Accesses/Shorten SRAM 
Write Duration
When the memory controller is configured for SDRAM, setting this bit to 
’
1
’
 disables the 
overlapping of bank accesses. When configured for SRAM, setting this bit to 
’
1
’
 short-
ens the time the IBM3206K0424 drives data on writes.
14
Parity or ECC
When set to 
’
1
’
, this bit causes parity to be generated. This bit set to 
’
0
’
 causes ECC to 
be generated. ECC is supported for DRAM only.
13-12
Reserved
Reserved
11-10
SRAM or SDRAM Latency
These bits indicate the delay between performing a read and the memory returning 
data. The bits are encoded as follows:
00
1 Cycle (SRAM only)
01
2 Cycles
10
3 Cycles (SDRAM only)
11
Reserved
9-8
Memory Type
These bits indicate the type of memory being used for memory. The bits are encoded 
as follows:
00
SRAM
01
ZBT SRAM
10 
Synchronous DRAM (SDRAM)
11
Enhanced Synchronous DRAM (ESDRAM)
7
Memory Unpopulated.
If this bit is 
’
1
’
, there is no physical memory connected to this controller.
Bit(s)
Function
Description