Re: Write Signal on Disk II Question

[Mike Willegal <mike@willegal.net>]

I think you are thinking that more data can be encoded than is done with 
the present scheme.  It might be an interesting achedemic exercise and 
if I were you, I'd study the QAM modulation schemes often used in 
broadband communications.   However keep in mind that there is only 1 
write output control to this drive, there is very limited bandwidth on a 
floppy interface and a relatively low signal to noise ratio, so you are 
very limited to what can be achieved.

see http://en.wikipedia.org/wiki/Quadrature_amplitude_modulation

Regards,
Mike Willegal

Bryan Parkoff wrote:
> Mike,
>
>
> > The field being generated is never absent when writing, it is changed in 
> > polarity for each one bit.  This is not a digital (on or off) signal.
>
>
>     I understand.  It is easy to create data array to hold digital binary 
> like digital_binary[100000] variable.  It may be possible to create 
> analog_binary[100000] variable.  The analog_binary[100000] variable uses 
> real number instead of integer number.  The real number can tell how much 
> voltage in positive polarity, negative polanity and perhaps absence of 
> polarity.  I am curious to see if it can be done in simulation to draw 
> analog clock cycle.
>     We know that we can be able to write more than two adjusted ZERO bits 
> without any problem.  The Read Sequencer in the logic state sequencer ROM is 
> designed to read only one or two adjusted ZERO bits maximum.  It could be 
> possible to read three or more adjusted ZERO bits reliably if you redesign 
> to modify state sequencer.  It may be 32 or 64 state sequencer instead of 16 
> state sequencer.
>     It is the reason why I am saying because I want to record all presence 
> of read pulse and absence of read pulse into RAM.  Maybe, special controller 
> card is capable of recording all instead of Disk II controller card.  What 
> do you think?
>     Is it true that copy-protected NIB image is less successful (like spiral 
> scheme) to run on Apple II Emulator?  It is possible that all copy-protected 
> images work on Apple II Emulator if recorded read pulses are used.
>
> Bryan Parkoff