Juan Castro jccyc1965 at gmail.com
Mon Apr 21 23:17:53 EDT 2014

Now I get it. the reason for ditching the syntax in HDB-DOS is: what
if there's a file called "147" (with no extension) in drive 97? Also,
harder to parse.

To be fair, the same kind of ambiguity existed in old RSDOS, but only
with one-digit names between 0 and 3.


On Mon, Apr 21, 2014 at 11:51 PM, Arthur Flexser <flexser at fiu.edu> wrote:
> I think there are some very rare circumstances where putting the drive
> number at the beginning may offer some slight advantage in programming.  If
> the filename exists in the program as a string variable, the drive number
> in prefix format will always be in character position one;  in suffix
> format, the drive number's position within the string depends on the length
> of the file's name.
> Art
> On Sun, Apr 20, 2014 at 10:52 PM, William Astle <lost at l-w.ca> wrote:
>> On 14-04-20 06:44 PM, Arthur Flexser wrote:
>>> Bill, putting the drive number before rather than after the filename has
>>> always been a legal alternate syntax in Disk Basic.
>> Huh. Who knew. It's the first I've ever heard of it, too. But I just
>> looked at the code in the original DECB ROM and sure enough, it
>> specifically checks for that case. However, the check only works for a
>> single digit drive number and the number can only be 0, 1, 2, or 3.
>> HDBDOS does eliminate that particular "feature". The existing code
>> couldn't possibly work with drive numbers more than one digit long and
>> given that the prefix drive number syntax is not documented anywhere
>> official, it was a prime candidate as somewhere to clobber for including a
>> patch for something else.
>> I suspect this one is possibly a holdover from other systems that used a
>> prefix drive letter or something like that.
>> There are a few other interesting variations accepted by DECB, too, so
>> this isn't particularly surprising. For instance, the manual says to use
>> "D" for a random file but "R" is also accepted. One can also prefix
>> coordinates for various graphics commands with @. You can also include
>> random text after the line number on a GOTO or GOSUB without provoking a
>> syntax error. You can also leave out the THEN keyword on an IF statement if
>> the command you want to run is GOTO or GOSUB.
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