Date : Fri, 01 Mar 1996 09:33:13 +0000 (GMT)
From : Roger Walker <Roger.Walker@...>
Subject: Re: Emulation systems
On Fri, 1 Mar 1996, James Fidell wrote:
>>> I'm currently having a discussion with Wouter Scholten about the
pro's and
>>> con's of the various methods. I agree that having one host file
correspond
>>> to one BBC file is very convenient. I do however see compatibility
problems
>>> with weird file names (as I think I've expressed earlier). The Beeb
allows
>>> characters like "?", "*", "\" and "/" in their filenames, thus breaking
DOS
>>> and Win32. I have seen commercial programs using "*" and "/". Also
>>> DOS/Win32 have no distinction between upper and lower case - DFS does.
>>
>> How about using Linux's UMSDOS method? One file in each directory which
>> stores 'extended' information. In this case, full BBC filename, load/exec
>> addresses. (UMSDOS uses the file for storing the full UNIX filename,
>> multiple timespamps and UNIX file permissions under a normal MSDOS FAT
>> filesystem.)
>>
>> The file you *actually* store is something like 8 chars of the BBC
>> filename (with wierdies substituted to '_' or something) with the
>> extension set to a 'magic value'. The simplest case is a number which you
>> use to lookup the correct entry in the index file. Eg.
>>
>> Files:
>> BBCTAPE_.___ Index file
>> BBC-FILE.000 file 'BBC-FILE'
>> Q_FILE00.001 file 'Q.FILE0000'
>> R_BBC_FI.002 file 'R.BBC/FILE'
>>
>> and the index file would contain entries like:
>>
>> Id# Filename Exec Addr Load Addr Next FileId#
>> === ========== ========= ========= ===========
>> 000 BBC-FILE FFFF8023 FFFF0E00 002
>> 001 Q.FILE0000 FFFF4000 FFFF4000 001
>> 002 R.BBC/FILE FFFFFFFF FFFFFFFF FFF
>
> I like this idea -- I'll probably put something similar into Xbeeb v0.4
> for the disk emulation.
>
As an extension (which makes it easier to write a DFS version), can we
include entries for the first 8 bytes of sector 0 & 1, which contain
the volume lable, and bootup options.
Roger Walker.