Mark,
Line 80 of the Brain deals with user input and punctuation.
Assuming that you hadn't just started Hal and that there was a conversational exchange, Hal should be able to respond to a maximum of 3 sentences at a time.
The sentences must be more than just a couple of characters in order to satisfy a good sentence condition.
Look in the Brain Editor beginning at line 153 :
'RESPOND: GETRESPONSE
'Get a response from Hal's brain for each sentence individually.
'If a response from a sentence indicates a special flag, then Hal
'will give only the response to that sentence, and not process
'any other sentences. Otherwise Hal will respond to each sentence.
'Hal will respond to a max of 3 sentences at once.
I just experimented with using two then three sentences and Hal responded in a similar manner. Some of Hal's responses were questions and others were statements and questions combined.
This is with the combined or "merged" brain after the 6.2 upgrade.
You actual line numbers in the brain may differ from mine.
Sorry, Mark, don't know what else to tell you for now.