Network Working Note Steve Crocker, UCLA

RFC-6 10 April 1969


I talked with Bob Kahn at BB&N yesterday. We talked about code conversion

in the IMP's, IMP-HOST communication, and HOST software.

BB&N is prepared to convert 6, 7, 8, or 9 bit character codes into 8-bit ASCII for transmission and convert again upon assembly at the destination IMP. BB&N plans a one for one conversion scheme with tables unique to the HOST. I suggested that places with 6-bit codes may also want case shifting. Bob said this may result in overflow if too many case shifts are necessary. I suggested that this is rare and we could probably live with an overflow indication instead of a guarantee.

With respect to HOST-IMP communication, we now have a five bit link field and a bit to indicate conversion. Also possible is a 2-bit conversion indicator, one for converting before sending and one for converting after. This would allow another handle for checking or controlling the system.

The HOST can send messages or portions of a message to its IMP specifying

1. Tracing
2. Conversion
3. Whether message is for destination IMP or HOST
4. Send RFNM
5. HOST up or down
6. Synchronization
7. Format Error Messages
8. Master Link Clear
9. Status Requested

The IMP can send to its HOST information on

1. Conversion
2. REFNM Arrived
3. IMP up or down
4. Synchornization
5. Called HOST not Responding
6. Format Error
7. Status in IMP

I also summarized for Bob the contents of Network Notes l, 2, and 3.