Direct screen writes (Re: Graphic characters in Norton Utilities SYS-V)

[Peter da Silva]

In article <1990Aug3.002317.12535 at pcrat.uucp> rick at pcrat.UUCP (Rick Richardson) writes:
> In some cases, it simply must be done.  Anything that wants to do
> graphics is going to have to go directly to the screen.

That's a different matter, though a less CPU-expensive standard than X for
using this resource would be desirable, I don't see one forthcoming. But
where acceptable standards exist (termcap, terminfo) they must be used.

> In other cases, direct screen writes are of tremendous value.
> People find it convenient to lean on the arrow keys to move
> around, and expect to stop on a dime when they see where they
> want to be.

There are many programs that provide this facility over even slow serial
ports, by either doing heuristics to determine when to do updates, or by
simply abandoning the current update of the screen image so long as input
is pending.

Another point to consider is that this sort of interaction is, while simple
to understand and implement, not always the most convenient for the average
user. The time spent making this fast could have been better spent implementing
more powerful tools such as incremental searches.

Optimisation is not free. Gratuitous optimisation can be translated directly
into missing features or later release dates. I consider optimising a program
for the special case of users logged in directly at the console, and not using
X, to be gratuitous.
-- 
Peter da Silva.   `-_-'
+1 713 274 5180.   'U`
<peter at ficc.ferranti.com>