Re: Cassette port input frequency range? And CPU MHz ranges.

[Egan Ford <datajerk@gmail.com>]

On Nov 27, 11:36 am, Egan Ford <dataj...@gmail.com> wrote:
> I just spent my yesterday creating a new cassette input method that is
> ~11x faster than the original (I loaded moon patrol in 10 sec vs.
> 109), and while it works with Virtual ][, it fails on the real thing.

Update.

My initial method used 16 frequencies (1, 3, 5, etc... pulses).  I
used positive pulses for the MSN (nibble) and negative pulses for the
LSN.  Then 4 pulses to write to memory.  Pulses were 1/64000 seconds.
This gave me an effective baud rate of 1777 with 14216 bps.

This worked consistently well with Virtual ][, however with my //e,
not so good.

Two problems:

1.  The (my) //e can not measure a single 1/64000 pulse, but it can
measure 2 @ 1/64000 or 3 @ 1/96000.
2.  The iPhone cannot output above 20000 Hz.

So, I changed my max frequent to 16000, recomputing my ranges.  Tried
64K and 96K with my Mac connected to my //e, and while not 100%, it's
close, however with the iPhone, garbage.  I was able to get the iPhone
to reliably send data if using a full symmetrical cycle.

Moving forward:

1.  I need to use full symmetrical cycles.
2.  More pulses/cycle.
3.  Try for 5x improvement.  10x with data compression.