Re: [Vaporware alert!] Portable Apple II Clone Concept

["mdj" <mdj.mdj@gmail.com>]

Michael J. Mahon wrote:

> Yes, that was my conclusion, too.  Disk ][ controllers are quite
> plentiful, so putting one inside the interface box seemed the most
> straightforward solution.

Either that, or since the controller is so simple, just replacing its
functionality with PIC + 74LS since you're building a circuit anyway.

> I did have some concerns about writing (I was mostly concerned with
> reading).  There are lots of jitter sources in PCs that would require
> some hardware solution for precisely timed write loads.

True. There might be just enough memory space inside a microcontroller
that an entire track can be buffered, but then the read/write logic
would need to written for the microcontroller instead.

Alternatively, the RTC in a PC has sufficient resolution to handle this
issue. Accessing it inside of an OS like Windows would probably be
problematic. You could get away with it on Linux were you can manage
close enough to realtime scheduling + access to the RTC from a usermode
application. Personally I'd be more than happy with read-only; the idea
for me is to get data off obsolete media, not put it back on ;-)

Another gotcha that's prevented me from playing with this extensively
in the past is the need for a -12V power source, which is something
that's not readily obtainable from a PC's user accessible ports and
power connectors. Somehow the thought of building power supplies makes
my teeth hurt :-)

Matt