[Coco] Nitros9 technical question....

[L. Curtis Boyle]

There is some code for floppy access that will re-read sector 0 for every read/write, to check if the unique identifier bytes have changed, but it greatly slows down real floppy access, so I believe most of that code has been removed (or at least shut off). If you re-enabled that, and using the CocoSDC’s speed of reading sectors to your advantage (and no seek times), you may be able re-enable that and have it detect disk swaps.

L. Curtis Boyle
curtisboyle at sasktel.net

TRS-80 Color Computer Games website
http://www.lcurtisboyle.com/nitros9/coco_game_list.html



> On Nov 11, 2019, at 8:31 AM, Bill Nobel <b_nobel at hotmail.com> wrote:
> 
> Hi Phil, the OS will handle the fact that more than one process can access a specific file. When you bring in the fact of switching a disk image the currently running programs will not know this. This of course could lead to issues.  Nitros9 was not built to handle a disk swap between programs running.  Though it can handle multiple disk access on  the same disk.
> 
> Sent from my iPhone
> 
>> On Nov 11, 2019, at 7:11 AM, Robert Gault <robert.gault at att.net> wrote:
>> 
>> Phil,
>> 
>> This list ought to be as good as anything else but you can try:
>> https://sourceforge.net/projects/nitros9/
>> Look at the Support and Discussion panels.
>> 
>> Regards your specific question, you could study the current NitrOS-9 disk I/O code as it also needs to deal with simultaneous disk access when more than one program is running. I assume that the disk code should ask the system for permission to access a disk and/or the system should keep track of the number of current requests for disk access.
>> Either disk or system code would, in your case, then keep track of the A/O AVR values and prevent cross routing.
>> 
>> Robert
>> 
>> Phill Harvey-Smith wrote:
>>> Hi all,
>>> 
>>> Is there still a Nitros mailing list that might be a more appropriate place for this?
>>> 
>>> Anyway I have a mostly working boot & disk driver for the DragonMMC interface, which can boot and
>>> access any mounted disk images. What I want to do is to convert the ROM utilities that allow you to
>>> list the contents of the SD card, and mount / unmount images to command line utilities for Nitros.
>>> 
>>> The DragonMMC works by having the FAT & SD reading part of the system handled by and AVR
>>> microcontroller, the 6809 side of things uses a set of I/O locations to exchange data with the AVR.
>>> This works for the disk driver code, and would be able to work for the utility code, however being a
>>> multi-tasking OS I need to ensure the utilities don't interfere with disk I/O that may be going on
>>> in the background.
>>> 
>>> Does anyone have any suggestions as to the correct way to do this?
>>> 
>>> Cheers.
>>> 
>>> Phill.
>>> 
>> 
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