RE: sd2iec ported to petSD

Hallo Nils,
 

> Though I don't like the idea of ripping existing drives

I have drives laying around where the mechanical parts are brooken
beyond repair. But even then everything can be done in a neat way: take
the 6502 or 6522 from the board and replace it with a PCB containing a
socket for this IC plus the Atmel and other needed hardware.


> Unlike the 8042, an AVR hasn't a hardware latch ...

Hmmm, too bad. But it triggered another idea:
In the 1541 a 6522 is used to control the mechanical drive and to
exchange data with the floppy. Using the PCB mentioned above, connect
the Atmel directly to this 6522 and let it emulate the mechanical drive.
IMHO this idea is usable for other drives as well.
The advantage of this idea: the ROM of the drive has not to be changed.

Another option is throwing in a bit more hardware but how much is "a bit
more"?


> Disadvantage: what about subdirectories?

That means changing the ROM. I have done it with my harddisk equiped
1541.


> And data exchange isn't that easy if you store it using
> Commodore DOS format instead of FAT16 etc.

In case of using it as floppy emulator, the drive doesn't see the SD
card at all so you are free to use any format. 
Using the IDE interface I use the C= format. Why convert it to FAT16
first? Harddisk are not meant to be removed as you do with SD-cards. I
use a removable harddisk and of course a PC doesn't understand this C=
gibberish so I wrote a Pascal program to exchange data.

Before my HD project I used an extra 6522 to make a connection to the
LPT port of a PC. The PC received the C= parameters and used them to
exchange data with a floppy image; in this case a D64. The Atmel can do
the same.


> But CF cards would be first choice, since they can operate
> at 5V, give you parallel 8 bit wide access

Problem 1: not all support 8 bit access. Problem 2: I tried some using
an IDE/CF interface and for one or another reason they didn't work :(
Both HD and CF worked fine in a PC but only the HD worked fine in my
1541.


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