[NTLK] Dock at 900K via serial hardware clocking

From: Adriano (adriano.angelillis_at_gmail.com)
Date: Fri Jul 01 2005 - 05:31:57 PDT


Hi,

i need help, as i cannot find the needed infos to make an accessory
which could let my MessagePad dock at 900K,
nor i have the skills to develop a single row of software, if it was
possible to do it this way.

Here is what i know:
  - thanks to software clocking (ser230400 extension) actually is
possible to connect the MessagePad to a Mac desktop at speedz of
230.4Kbps,
but the Newton mainboard serial chip (Zilog 8530) is capable of speedz
of 2000Kbps (2Mbit/s) when using external hardware clocking.
[I.e.: some old serial Epson printers used an onboard hardware clock
device to push at 900K the serial connection with a Mac,
and old serial QuickCam cameras estabilished connection at 1Mbit/s for
audio/video communications]

Zilog datasheet is available to the link below:
http://www.zilog.com/docs/serial/ps0113.pdf

Some thoughts:
  - i think that if we could dock the MessagePad at 2Mbit/s, it would be
great! Don't you?

  - although i am aware of the differences between a Macintosh and a
MessagePad mainboard, as the Zilog 8530 serial chip was used on old
Macs too,
maybe some compatibilities on the serial hardware layout could exist.

  - the serial to usb adapter i have, build upon a FTDI chip, accept
clocks at speedz of 900Kbps, so i thought:
"why not trying to configure a device with the purpose of clocking the
Newton serial connection at 900K?"

The point is that Apple spent only a few rows around the argument of
serial clocking on 'Inside Macintosh' pages,
and i found only a few reports on the web about a somewhat succeful
serial connection clocked at 1Mbit/s,
if you are interested, just take a look to the link below:
http://www.rdrop.com/~cary/html/serialportdocs.html#mac

Any suggestions will be really appreciated.

Thanks in advance,

Adriano

'Green is better' pages
http://homepage.mac.com/adriano.angelillis/

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