[Coco] Read coco disks on a PC

[John E. Malmberg]

On 3/15/2012 11:28 PM, Darren A wrote:
> On Thu, Mar 15, 2012 at 9:18 PM, John E. Malmberg wrote:
>>
>> As I stated before:
>>
>> The buffers are fixed in memory for Disk Basic.
>>
>> The DISK IO routines will read all 512 bytes first into the disk buffer and
>> then overrun into the verify buffer.
>>
>> But when the ROM routines try to use the data, they will only read the first
>> 256 bytes from the disk buffer.
>>
>
> Not all operations in disk basic go through the primary buffer at $0600.
>
> Open data files have their own separate buffers and operations like
> COPY and BACKUP use free memory to load in multiple sectors.
> Overrunning in these cases could corrupt the disk management
> structures, the basic program or the stack.

It has been a while since I looked at the dissassembly listing of the 
Disk Basic ROMs, but from what I remember, there was only one set of 
routines that did the sector reads/writes and they were hard coded to 
use a specific area of RAM for their buffer.

This program would also be special purpose for data interchange, not a 
solution for general use of 512 byte formatted floppies with Disk Basic.

Regards,
-John
wb8ytw(at)qsl.network
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