[Coco] Re: Disk Basic and 512 byte block floppies.

[John E. Malmberg]

Theodore (Alex) Evans wrote:
> On Jan 18, 2004, at 5:07 PM, John E. Malmberg wrote:
> 
> You are right about the problem.  I would have solved it with POKE 
> DO+3,S/SS and POKE DO+3,S/DS

The result would depending on rounding.  Would .5 be interpreted as 0 or 
1 after the conversion?

>> Then I need to modify my COCODISK program to be able to handle 512 
>> byte sector floppies.
>>
>> For the DOS version, I should be able to auto detect the sector size.
>  
> I thought about showing you an auto detect algorithm for the coco as well.
> Read T0,S1 into two buffers.
> Invert the values in one.
> Reread To,S1 into the inverted buffer
> Find where the two differ.

I do not think that would be reliable because the floppy could be blank 
on that track.

For MS-DOS, I can just try the two sector sizes and see which one gives 
a data error.  That still may be a problem, because I am getting a lot 
of access timeout errors on the floppy.  For some reason, occasionally I 
have to reinsert the floppy in the drive to get it to read.

But these ongoing problems with reading COCO floppies is one of the 
reasons I looked at this experiment.

-John
wb8tyw at qsl.net
Personal Opinion Only