Re: Data transfer methods

From: Jim Brain (
Date: 2005-05-12 22:17:00

> On Thu, May 12, 2005 at 09:39:58AM -0500, Jim Brain wrote:
> I have the impression that NTFS supports UCS2 a.k.a. 16-bit Unicode.  So,
> it would be logical for VFAT to support that as well.
I didn;t want to state it, but I believe it is UCS2.  They call it DBCS,
but Iwasn;t sure if the two are the same.
> True.  Luckily, FAT is only needed for portable media.  In cable-based
> data transfers, the file name mapping can be implemented in the host
> software.
And mapping in such software seems trivial.

> When writing to a memory card, the Commodore has to take care of this.
> I guess VFAT will be the most straightforward solution, even though 16-bit
> Unicode may lack some of the PETSCII characters.

Are we stating there is a UNICODE std for PETSCII?  All I see is:

and a note in Wikipedia article for PETSCII stating:

Mapping PETSCII to Unicode is impossible, since not all PETSCII graphics
characters are encoded in Unicode. Unmappable characters should be
replaced by the Unicode replacement character, U+FFFD (�), or
mapped to the private-use range of Unicode.

The proposed mapping is in a private use area, and fits in 16 bit values. 
So, if you follow the proposed mapping, you'd be fine.  If you intend to
map to existing characters, I think it would be impossible no matter the
UTF size.

> I appreciate your braveness.  I look forward to that and will happily
> help with testing.  I have a Digital VT420 terminal that is very handy,
> especially when slowed down to 300 bps.

I'm not sure I'm brave, just pragmatic.  If I have to write USB drivers
anyway, it matters not which thing I write for.

Still, I'm trying to keep VIP from needing to support XON/XOFF at all.  If
I succeed, I won't be embarking on such a development effort.

I'm having fun doing the CBM projects. I always wanted to do them, but I'm
only a competent firmware developer, not a genius, and I need tools to
help me (scope, analyzer, etc.)  Only recently have I been able to acquire
such items.  With the right tools, progress goes much faster.

I remember starting to develop an HC11 based AT keyboard controller
interface to the 64 long ago, but gave up because it would not work and I
was not smart enough to hand walk the code and see what was going wrong
with my development effort.  Last year, the same thing took an evening
with my scope and my analyzer.


Jim Brain

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