Alex Freed
2006-07-20 10:03:35 UTC
I have finished a prototype of a new mass storage device for Apple 2 that
uses MultyMedia Cards.
So what, you'll ask. There is already a CF interface.
Yes and no. My toy has a small AVR microcontroller on board and 2 modes of
operation.
The trivial mode simply interfaces the MMC to Apple as yet another ProDOS
storage device.
The fun starts with the "smart" operating mode. The device looks to Apple as
a Disk ][ controller.
So Apple happily reads nibble images as if they were real 5 1/4" floppies.
This allows using
images of DOS 3.3 disks or any other .nib images. For example a couple of
games that do not
use DOS work fine.
The software is not quite finished: I need to add an application that will
run on Apple
and select one of many .nib images to use. My prototype just uses a single
image, but that is
not very difficult.
The firmware can use a lot of improvements too. Currently I feed Apple a new
byte every time
it asks for one instead of changing it every 32 msec. Seems to work for
quite a few images, but
won't work with many protection schemes.
The big question is is there any interest in this device? If there is, I can
make a small production
run and offer for say $100. If not, I'll be the only owner of the only
prototype.
The board has an AVR micro and a CPLD for fast interfacing. Originaly I
though that an AVR
running at 16 MHz is fast enough to do everything in software, but it is
not. In addition the
CPLD acts as a perfect 5v to 3.3v converter - MMC uses 3.3 V. I can add an
EPROM
to make this card bootable. Currently I boot from a real disk and DOS can
see the other
"disk" in another slot.
The MMC card can have up to 4 partitions. Some partitions up to 32 MB can be
seen
as ProDOS volumes and one can have any number of .NIB images.
Future driver will be able to see 2 images at once as drives 1 and 2.
uses MultyMedia Cards.
So what, you'll ask. There is already a CF interface.
Yes and no. My toy has a small AVR microcontroller on board and 2 modes of
operation.
The trivial mode simply interfaces the MMC to Apple as yet another ProDOS
storage device.
The fun starts with the "smart" operating mode. The device looks to Apple as
a Disk ][ controller.
So Apple happily reads nibble images as if they were real 5 1/4" floppies.
This allows using
images of DOS 3.3 disks or any other .nib images. For example a couple of
games that do not
use DOS work fine.
The software is not quite finished: I need to add an application that will
run on Apple
and select one of many .nib images to use. My prototype just uses a single
image, but that is
not very difficult.
The firmware can use a lot of improvements too. Currently I feed Apple a new
byte every time
it asks for one instead of changing it every 32 msec. Seems to work for
quite a few images, but
won't work with many protection schemes.
The big question is is there any interest in this device? If there is, I can
make a small production
run and offer for say $100. If not, I'll be the only owner of the only
prototype.
The board has an AVR micro and a CPLD for fast interfacing. Originaly I
though that an AVR
running at 16 MHz is fast enough to do everything in software, but it is
not. In addition the
CPLD acts as a perfect 5v to 3.3v converter - MMC uses 3.3 V. I can add an
EPROM
to make this card bootable. Currently I boot from a real disk and DOS can
see the other
"disk" in another slot.
The MMC card can have up to 4 partitions. Some partitions up to 32 MB can be
seen
as ProDOS volumes and one can have any number of .NIB images.
Future driver will be able to see 2 images at once as drives 1 and 2.
--
-Alex.
-Alex.