Stevie (vi clone)

[Tom Neff]

In article <uJ2eo1w162w at cybrspc> cybrspc!roy at cs.umn.edu (Roy M. Silvernail) writes:
>I've played about pretty extensively with Stevie 3.69 whilst modifying
>it for BBS use (under MS-DOS). I have compiled both with and without
>BIOS video writes. The non-BIOS routines are _significantly_ faster on
>my machine. The only difference I can see is that BIOS video doesn't
>require the NANSI driver. Perhaps I just have a lethargic BIOS?

Very likely so.

There are three ways a program can write to a PC screen: (1) use the
BIOS interface, (2) pump escape sequences at the DOS CON: device in the
expectation that some ANSI driver (ANSI.SYS, NANSI, FANSI-CONSOLE) will
be installed; (3) toggle the screen hardware directly.

Programs that use the BIOS succeed almost everywhere, but they rely on
the BIOS's efficiency and speed optimization, which frequently stinks.
Some of the old IBM BIOS code, for instance, was an absolute pig on
character write and flashed the screen repeatedly during scrolls to
avoid snow during the retrace interval.

Programs that use ANSI escape sequences are hostage to the presence,
efficiency and completeness of the user's installed screen driver.  With
the right driver (NANSI or FANSI) applications can handily beat BIOS
based times.  This is probably the case with Stevie 3.69 on Roy's
machine.

Programs that write directly to the video hardware can often outperform
everyone else, but are also most likely to have portability problems
across various PCs and software environments.

-- 
There's nothing wrong with Southern California that a   ~~ Tom Neff
rise in the ocean level wouldn't cure. - Ross MacDonald ~~ tneff at bfmny0.BFM.COM