Number: 1260

Date: 30-May-84 15':25':52

Submitter: Wallace

Source: Wallace

Subject: CHAT should clear line when it receives CR from remote host

Assigned To: 

Attn: vanMelle

Status: Incomplete


Problem Type: Bug

Impact: Moderate

Difficulty: Moderate


Priority: Perhaps

System: Communications

Subsystem: PUP Protocols

Machine: 1132


Lisp Version: 21-May-84 01':21':39

Source Files: 

Microcode Version: 5124

Memory Size: 4096

File Server: 

Server Software Version: 


Description: '
1> CHAT should clear the line when it receives a CR from the remote host.  Apparently the DM2500 does this, and all the hosts I''ve used expect it.'
I thought this was a Stanfor Twenex problem, since it only occurs there, but they claim to implement the standard correctly.  I really don''t know who''s at fault, but could someone who understands what''s going opn look at it?  We''ve been getting complaints from out students.'
Date': 31 May 84 15':47 PDT'
A DM2500 does NOT clear the line when it receives a CR.'
I''m not sure what your particular problem is, but perhaps it is related to a compromise in the Chat code with respect to a misfeature of the DM2500.  Namely, the DM2500 has autolinefeed': on receipt of a CR, it performs a CR, LF.  So that this doesn''t screw up when receiving a standard CR, LF, it goes into a state where if the next incoming character is a LF, it ignores it.'
Chat emulates this by performing a CR and waiting for the next character; if it is anything other than a LF, it first does a LF.  The end result of this procedure is exactly the same as on a DM2500, but its intermediate state is different': if the host sends naked CR and waits, then Chat has not yet gone on to the next line.  This is a "feature" when you are talking to hosts that don''t know about DM2500''s but do perform scroll holding between the CR and the LF sent to terminate the last line of a screen full.  Maxc is an example.'
If this is indeed your problem, we can discuss ways around it.'


Test Case: 

Edit-By: vanMelle

Edit-Date: 12-Jul-84 14':38':27