Re: How do I add firmware to a card?

["RedskullDC" <RDC@oz.org>]

Hi David, et al.

"David Empson" <dempson@actrix.gen.nz> wrote in message 
1hsc1jh.1hqbl6aapwbr5N%dempson@actrix.gen.nz">news:1hsc1jh.1hqbl6aapwbr5N%dempson@actrix.gen.nz...
> <aiiadict@gmail.com> wrote:

> I don't recall whether the 65C02 in the UniDisk 3.5 runs at a higher
> clock speed than the Apple II: if data is transferred between the
> UniDisk CPU and the 3.5" drive mechanism under processor control then it
> would need to run at about 2 MHz (or faster) to be able to keep up with
> the data rate (16 microseconds per byte, which is twice as fast as a
> 5.25" drive). If they used some form of DMA, then the UniDisk's CPU
> could be running at the same clock speed as the Apple II.

The IIgs firmware manual covers the smartport calls , and the internal 
memory
map for the 65C02 in the Unidisk3.5.

It uses an IWM chip which is clocked at 7MHz to achieve the 16ms/byte
you mention. The 65C02 is running at 2MHz.

> Assuming you were just transferring 1 KB of data to/from the UniDisk
> RAM, the transfer time would be in the order of 4.5 ms each way (9 ms
> total).
>
> If the UniDisk runs at 1 MHz, the computation would have to take more
> than 9 ms (with the Apple II working on another block of data at the
> same time) before you would gain anything from the "parallel computing".
>
> If the UniDisk runs at 2 MHz, the computation would have to take more
> than 4.5 ms (with the Apple II working on a half-size block of data at
> the same time) before you would gain anything.
>
> This all assumes you actually have a UniDisk 3.5. They are relatively
> rare, compared to an Apple 3.5 Drive.

I happen to have one here on my //e :)

Cheers,
Leslie