[Coco] a not very important drivewire question

[Gene Heskett]

On Wednesday 16 July 2014 22:46:18 Robert Gault did opine
And Gene did reply:
> Robert Hermanek wrote:
> > I just noticed today my drivewire HDBDOS will not accept command
> > DRIVE #255, gives me an FC error.  0 - 254 are fine.  I guess I
> > figured any byte value would work.  Any explanation why 255 not
> > allowed?
> 
> That appears to be an error in the source code for HDBDOS in toolshed.
> 
> The file hdbdos.asm defines MAXDN for Drivewire as 255. That would make
> sense if the test further down in the program was based on the highest
> value for a drive rather than the maximum number of drives.
> With a highest value of 255, that is a total of 256 drives.
> 
> * Select Device ID number
> DNUM           jsr       <$9F                Parse over "#"
> DSET05         jsr       LB70B               Evaluate argument
>                 cmpb      #MAXDN-1            Legal?
>                 bhi       FCERR               No, ?FC ERROR
> 
> Given the test, the DW MAXDN should be 265. Then you would be able to
> enter DRIVE#255
> without error.
> 
> Now why are several people saying that it works for them? Probably
> because they are confusing the command DRIVE#n with DRIVEn. One
> selects a bus number (an actual physical drive) the other selects a
> Disk Basic "disk" on a hard drive.
> 
> I strongly suggest that
> 
>                 IFDEF     DW
> Vi.PkSz        equ       0
> V.SCF          equ       0
>                 use       dwdefs.d
> 
> RBLK           equ       OP_READEX           Read Block
> RRBLK          equ       OP_REREADEX         ReRead Block
> WBLK           equ       OP_WRITE            Write Block
> 
> 
> Carry          equ       1
> IntMasks       equ       $50
> E$CRC          equ       243
> E$NotRdy       equ       246
> PIA1Base       equ       $FF20
> DATAADDR       equ       PIA1Base
> TDELAY         equ       8                   Retries in the case of
> DriveWire MAXDN          equ       255                
> !!!!!!!!!!!!!!!!!!!!!!!!!!!!!! ENDC
> 
> the value of MAXDN for DW be changed to 256.
> 
> Robert

Whats the data size of MAXDN? 256 is a 2 byte value, as its 0x0100, and 
needs an int to store it.

Just checking ;)

Cheers, Gene Heskett
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