[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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