stepping machanism of Apple Disk ][ drive (was Re: Heatkit 51/4 floppies)

From: Dwight Elvey <elvey_at_hal.com>
Date: Mon Apr 12 12:02:27 1999

allisonp_at_world.std.com (Allison J Parent) wrote:
> <I knew somebody woudl come up with a good example. That 6809 code is
> <probably the closest thing I've seen in a micro. The 8051 uses a similar
> <approach, pointing to the table with the datapointer and uses the
>
> The 8051 is very ugly in other places.
>
> Then there are the NEC uPD 78xx series that are similar in register layout
> to z80 but code wise, not close. They have a table lookup instructions for
> that exact task. They are targetted as rom based controllers and code
> efficientcy is a requirement but often controller don't need to preocess
> the kinds of things a PC (or other general purpose computer) would.

Hi
 Even the 4004 had an indirect table jump, so what is all the
noise about.
Dwight
Received on Mon Apr 12 1999 - 12:02:27 BST