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IBM2520L8767
IBM Processor for ATM Resources
atmrm.chapt05.01
08/27/99
On-chip Checksum and DRAM Test Support (CHKSM)
Page 353 of 553
17.9: CHKSM Internal State
Internal state of checksum.
Note: This register should not be written unless you know what you are
doing!
7
RP-ADD -- Ripple Addend
When this bit is set, the ripple base register counts up by 1. When this bit is cleared,
the ripple base register counts up by eight.
6
CL-IP -- Clear IP
When this bit is written it will clear the CHKSM TCP/IP Checksum Data Register and
itself. The result of this will be that this bit will never be read as a ‘1’. The internal align-
ment is also cleared.
5
RP -- Ripple
When this bit is set, a ripple pattern will be used in both the read and write test modes.
The ripple pattern is used instead of the constant test pattern. When this bit is reset,
the constant test pattern is used for the test mode data.
4
MS -- Memory Select
When this bit is set, all CHKSM memory accesses are to the control memory. When
this bit is cleared, all CHKSM memory accesses are to the packet memory.
3
RW -- R/-W Test Mode
When this bit is set, the entity will take the data that is read, and compare it to the
test/ripple pattern.
When this bit is reset, the checksum entity will write data using the test/ripple pattern to
the DRAM.
2
TM -- Test Mode
When this bit is set, the entity will take the data that is read, and compare it to the
test/ripple pattern, or will write data using the test/ripple pattern to the DRAM depend-
ing on the setting of the RW bit. In both cases, the reading or writing will continue until
either an error is encountered, or the CHKSM Read/Write Count Register counts down
to zero. When this bit is reset, the checksum entity will operate as described by the
other bits. Test and CHKSM modes are mutually exclusive, and test mode takes pre-
cedence.
1
ET -- Enable TCP Checksum
Updates
When this bit is set, the entity will collect the TCP checksum in the CHKSM TCP/IP
Checksum Data Register.
When this bit is reset, the CHKSM TCP/IP Checksum Data Register will not be
changed by data that is read from the DRAM.
Test and CHKSM modes are mutually exclusive, and test mode takes precedence.
0
EE -- Enable Entity CHKSM
When this bit is set, the entity will run as specified.
When this bit is reset, the entity will not run.
Length
3 bits
Type
Read/Write
Address
XXXX 0A3c
Power On Value
X’00000000’
Restrictions
None
Bit(s)
Name
Description