On Tue, 12 Jul 2022, Wilhelm Spiegl wrote:
Hi, I just looked at my website
http://home.mnet-online.de/willybilly/fdhelp-108a-internet/en/hhstndrd/base/graftabl.htm
and noticed that the documentation for graftabl from 2007 is extremely short,
strictly speaking: there is none.
As I never learned what graftabl is really good for, could you please write and
add at least a short and
understandable documentation and some examples for it. Would be very nice and
helpful for me and the FD help.
Thx for doing so
It serves a very specific purpose, and isn't very useful these days (which
is why it was relegated to supplemental with MS-DOS 6 and omitted with PC
DOS 6.1).
Basically, when you enter graphics mode on a CGA, it gets the first half
of its character set from F000:FA6E, and the other half from wherever
INT1F points. INT1F by default points to nothing in particular so you'll
get garbage if you try to output 80-FF. GRAFTABL loads this missing half
of the character set into RAM, and points INT1F to it.
On an EGA or VGA, DISPLAY.SYS and MODE do everything that GRAFTABL does
and more, so it makes no sense to install it there. Also, it doesn't do
any good in text mode.
When it was introduced in PC DOS 3.0, it only contained one character set.
This became 4 (437, 860, 863, 865) in 3.3, 5 (850 was added) in 4.0, and 6
(852 was added) in 5.0.
Because in the time between MS-DOS 5 and 6 it became more common to have
up-to-date PCs, with VGA, GRAFTABL became even less useful than it was,
and was relegated to the Supplemental disk starting with version 6.0.
GRAFTABL is the same as GRAFTABL 437, probably for backward compatibility
with MS-DOS 3.0-3.21.
-uso.
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