[Coco] CocoSDC

[Mark Marlette]

Nick,

As I can't specifically talk the details about Darren's project and how he handled the FAT translation. I can talk on how I did it on my prototype.

LFN support and handle support takes a fair amount of RAM. IIRC Darren used an ATmega328(??) which has basically 2K of RAM. There is a hardware limitation, he probably can't add LFN support due to RAM restrictions.

I don't recall the exact numbers on my systems, and each platform is slightly different. Thus my current SD Controller has 512k of SRAM as it was a part I already had. My development .lib for the FAT, like many other uCs .libs doesn't support LFN. LFN is present in the SD's FS so it is just a matter of creating the routines to process the LFN. I purchased the .asm source library rights so I can distribute my work, part of the license agreement. I am fairly verse in it as I created a freeware READ ONLY version of SD bootloader with AES decryption capabilities so it would fit in the bootloader space. No room for LFN there!!!! The DOS lib wouldn't even fit in the bootloader without a special.lib created. Firmware updates are placed on the SD's root and then powered up and FLASH updated.


Routines would have to be created and not sure how much FLASH space is left over, 32k is a fair amount, so guess SRAM is the problem. IIRC Darren was also on assembly language which, makes the task a bit more challenging. He created the CoCoSDC, so talent is not a question here, more likely if he wants to add it is the real question.


I am currently on the Xmega256, which is a monster and at 32MHZ, have over clocked it to 50MHZ, no problem, just playing around, have heard of 72MHZ OCs, really powerful.

This is just my experience based upon my product development. I know nothing of Darren's design, he of course would know best on LFN support on the CoCoSDC.

 
Regards,

Mark Marlette
http://www.cloud9tech.com
mark at cloud9tech.com


________________________________
 From: "nickma2 at optusnet.com.au" <nickma2 at optusnet.com.au>
To: CoCoList for Color Computer Enthusiasts <coco at maltedmedia.com> 
Sent: Sunday, October 12, 2014 11:08 PM
Subject: Re: [Coco] CocoSDC
 

The CoCoSDC is shaping up to be the premier disk controller for the
modern day CoCo.

I think it has now defined "the new standard". Goodbye obsolete floppy
drives, hello SD cards.

With the number of CoCoSDC's out there, Darren has got to provide a
new firmware update to include new features to the CoCo.

Certainly the support of longer (FAT16) filenames would be cool and
saves renaming the DSK images from the PC into a 8:3 format.

Maybe an option to set the bootup video mode of RSDOS (Width80 or
Width40) and a user selected colorset (Green-on-white, white-on-blue
etc).

Nick 


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