[TUHS] I swear! I rtfm'ed

[mah@mhorton.net (Mary Ann Horton)]

The move was from termcap to terminfo.  Termlib was the library for termcap.

There were two problems with termcap.  One was that the two-character 
name space was running out of room, and the codes were becoming less and 
less mnemonic.

But the big motivator was performance.  Reading in a termcap entry from 
/etc/termcap was terribly slow.  First you had to scan all the way 
through the (ever-growing) termcap file to find the correct entry.  Once 
you had it, every tgetstr (etc) had to scan from the beginning of the 
entry, so starting up a program like vi involved quadratic performance 
(time grew as the square of the length of the termcap entry.)  The VAX 
11/780 was a 1 MIPS processor (about the same as a 1 MHz Pentium) and 
was shared among dozens of timesharing users, and some of the other 
machines of the day (750 and 730 Vaxen, PDP-11, etc.) were even slower.  
It took forever to start up vi or more or any of the termcap-based 
programs people were using a lot.

I wrote a paper about it for Usenix in 1982, but it seems to be lost to 
Google.  Here is a nice write-up Pavel Curtis posted about it with more 
detail about the motivation:

http://www.informatica.co.cr/unix-source-code/research/1982/0711.html

     Mary Ann

On 01/01/2015 07:03 AM, Johnny Billquist wrote:
> On 2015-01-01 02:29, Erik E. Fair wrote:
>> All those terminal quirks made writing termcap entries challenging
>> (I wrote a few), and made the comments in the termcap file interesting
>> reading for the frustration and cursing of terminal firmware authors.
>> All kinds of history of the evolution of terminals is captured therein.
>>
>> The removal of the ability to read the source is - IMHO - what
>> greatly impeded adoption of the AT&T "termlib" replacement for
>> termcap: they stopped distributing the terminal database source
>> (they distributed just the binary "compiled" versions), and made it
>> harder to write new entries.
>
> I was way to removed from the action to know, but why did people 
> slowly move over to termlib? Was there really any advantages over 
> termcap?
>
>     Johnny
>