🚀 go-pugleaf

In article <8904212229.AA22257@es56.escd.uucp> karl@es56.UUCP (Karl Rowley) writes:
>
>Now that the ST has a Postscript emulator, what about a box to connect
>it to Appletalk?  The Mega ST and laser printer make a decent postscript
>device, but they have to be fed through the parallel or serial port.
>This cannot really compete with other printers that can be connected 
>directly to Appletalk.

I presume by Appletalk you mean Localtalk, not something else like Ethertalk.
Localtalk runs at 230.4kbps. According to the Mac hardware references, the
serial port is driven in async mode at this speed (using a Zilog 8530 Serial
Communications Controller).

The ST's serial port controller, the Motorola 68901 MFP, is only rated for
62.5kbps in async mode. The clock signals fed to it in the ST limit the
maximum async rate to 61.4kbps. Using the internal clock in synchronous mode
gives you speeds of 153.6 and 307.2kbps. I'm not sure that trying to run in
synchronous mode will help you much here, either.

Perhaps it could be done, but you'll need to install your own crystal to
get the timing right. The ST currently uses a 2.4576MHz crystal, you would
probably want to use a 3.672MHz crystal, like the Mac uses. Of course doing
so will screw up normal use of the serial port - beyond 4800bps, the speeds
are no longer an exact match. (e.g., instead of 9600bps you'll get 9587.
Probably a small enough discrepancy that it won't cause problems, but you
never know. Also, there seems to be another discrepancy regarding speeds -
with a clock rate of 3.672MHz, the closest they can get to 230.4kbps is 229.5k.
But, I guess that works too...)
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