Re: Software for MS-DOS 1.25

Steve Gray wrote:

> I see that you've re-ordered the font to conform to the cbm-ii (petscii)
> ordering. When the 8088 side writes to the CBM-II screen I assume there
> is an ASCII to PETSCII translation. Does this cause problems with pc
> apps that "read" the screen, or is there a screen read function that
> also does the translation? What I'm getting at here, would it be better
> to eliminate the translation and write to the screen in ASCII and keep
> the pc font in normal ascii order? Will this increase compatibility, or
> is this a non-issue?

You cannot write ASCII to the screen directly, because on the CBM-II
only 128 characters are available. Unlike the C64, Bit 7 is set in
hardware to perform reverse.

Therefore you have to pack 256 ASCII characters into 128 PETSCII
characters. At this moment, the table "IPC_CharConvert_Table" in the
source code is responsible for this.

As for screen read, the function INT 10,8 is currently unimplemented. I
don't know if much software that uses it - normally software knows what
it has written :-) It would require writing a new 6509 function too,
because there is currently no such I/O function available.

Regards,
Michau.






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