Re: Disk images: from //e to Mac via PC?

[m.kelsey@spam.eecs.wsu.edu]

In article <1998052801482900.VAA00646@ladder01.news.aol.com>,
	supertimer@aol.com (Supertimer) writes:
> m.kelsey@spam.eecs.wsu.edu wrote:
> 
>>supertimer@aol.com (Supertimer) writes:
>>
>>So I'm to believe the IIgs can sustain transfer rates of 230Kbit/sec?
>>My stock //e (1Mhz) couldn't even pump out data at a full 19200 baud
>>over null modem.  My stock IIgs can barely reach to 48Kbit out of
>>56Kbit on upload.  I find it difficult to believe a stock IIgs can
>>sustain 230Kbit unless an accelerator were in place!
> 
> In this case, CPU speed is not the limiting factor, but the serial
> hardware.  The standard IIgs is 2.6-2.8Mhz, right?  Yet you can
> do 48kbit...put an 8Mhz ZipChip in a IIe and it CAN'T go 19200
> even though the CPU speed is faster than the GS.

The Apricorn .... could pull 38400 with the //e, however, my //e
could crank data out a 19200, but receive was substantially slower.
If I set the GS serial port to 19200 it sends and receives at
nearly the peak rate.  This must be due to a major improvement
in hardware.

> For the same reason, an AppleTalked GS can link at 230kbit.
> When AppleTaking, the GS uses the hardware characteristics
> of the serial chip and motherboard to transfer at these high
> speeds.  Timing is critical, so many interrupts are shut off...this
> messes up things like 3200 color mode.
> 
> Remember...the GS can pump MUCH faster than 230kbit
> with an SCSI card...or even with a floppy controller (which is
> serial).  The serial hardware is the limiting factor, not the CPU
> speed (except when doing error checking stuff like Zmodem).

That is a good point, I hadn't considered DMA as possibility for 
onboard dedicated hardware.  From what I've benchmarked, my IIgs 
doesn't pull more than 150K/sec from hard drives capable of 600K/sec
on a faster PC.  While this value is far greater than 230Kbit, it
is using DMA.  Knowing the IIgs can handle such transfer rates it
opens some new light on the subject.  

Now this brings up another important point, I stumbled onto some
TOPS cards which I have heard rumoured to be AppleTalk compliant.

If this is the case, this would be a nifty method preferred over
serial link.  The problem is, where to find TOPS software, the
proper connectors, and if the dad-gum things are even AppleTalk
complaint!

-- 
 -/\/\ichael-
From: m.kelsey@spam.eecs.wsu.edu