Number: 159

Date: 18-Mar-84 14':46':18

Submitter: Sannella.PA

Source: Masinter.PA

Subject: RS232 terminal emulation

Lisp Version: 

Description: '
Date': 16 Mar 84 17':21':17 PST (Friday)'
From': Masinter.PA'
Subject': rs232 task'
To': Sheil, Purcell'
cc': LispSupport'
The RS232 task  (which we are considering for Mitch) should include VT100 emulation over RS232 lines. Here is Chris Halvorsen''s description of what is necessary.'
Date': 16 Mar 84 17':18 PST'
Subject': DSPVTS &RS232 MODEM'
Jonl is not in, but the situation with DSPVTS , as I understand it, is that it needs code to simulate an intelligent terminal.  This is the small matter of programming,  i.e. to see to it that the right functions get called when escape sequences come in from the host.  I thought that there might simply be an a-list of escape sequences and screen operations, in which case implementing a new terminal type would be very simple, but that is not the case.'
Furthermore,  Jonl expressed the worry that certain screen operations on a Dlion, like clearing the screen, inserting a line etc.  will take so long that the host will start sending "text" before the DLion has completed the screen operation since it believes it is talking to an intelligent which is faster at doing this. There is not buffering in DSPVTS, so  characters  sent while the DLION is busy would fall on the floor.  Jonl suspected that you might not be able to run faster than 300 baud.  There is obviously something here which could need some work.'
Date': 26 MAR 84 15':12 PST'
From': JONL.PA'
Subject': Re': rs232 task'
To':   Masinter, Sheil, Purcell'
cc':   LispSupport, JONL'
In response to the message sent  16 Mar 84 17':21':17 PST (Friday) from Masinter.PA'
Just to review the "bottlenecks"':'
1) although the TTYPort seems to be operating better than the Martin-board'
    interfacer for the Dolphin, it still doesn''t not buffer characters; thus'
    the liklihood of droppin characters when one of the DSPVTS functions is'
    called. [DSPVTS is the functional support for Virtual Terminal Service'
    under the Interlisp-D windowworld -- has functions like DSPINSCHAR for'
    "inserting" a character, DSPDELLINE for "deleting" a line.  Remember also'
    that DSPCLEOL is in the system now, for "Clear-to-end-of-line"]'
    Sometime ago I asked Beau for an estimate of priority of the converto-to'
    RS232C port; that conversion should clear up the dropped character problem.'
2) the unix file TERMCAP has all the information we need for terminal emulation'
    (and terminal drivers, if ever we should have to do it!);  I had planned'
    to hand-transcribe enough information into Lisp to support a simple '
    emulator for the Heath 19 and VT52.  Current ethernet Chat''s emulation of'
    a DM2500 is a little non-standard in that it has more "escape sequences",'
    but should fit rather easily into the DSPVTS mold.'


Test Case: 

Edit-By: Sannella.PA

Edit-Date:  3-Apr-84 10':44':19


Assigned To: 


Disposition: '
[Date':  2 Apr 84 20':17 PST'
Subject': AR 159': priority and difficulty '
Priority': Perhaps'
Difficulty': moderate'
Impact': Serious to some users, merely annoying to others]

System: Communications

Subsystem: RS232



Microcode Version: 

Memory Size: 

File Server: 

Server Software Version: 

Difficulty: Moderate


Impact: Moderate

Priority: Perhaps

Status: Open

Problem Type: Performance

Source Files: