🚀 go-pugleaf

In article <1992Aug31.230842.11663@Trirex.COM> bmehlman@trirex.com writes:
>I am writing an application that needs to send asynchronous serial data at  
>a speed of 250 Kbps.  Specifically, I'm trying to generate DMX-512  
>standard multimedia device control signals.
>
>This leads to two questions:
>
>1) Can the NeXTs serial ports physically go that fast?
>
>2) Is there any software support for this type of operation?
>
>As far as #2 goes, the NeXT docs and FAQ state that the top supported  
>speed is 38.4...  I'm hoping that there may be others who have written  
>alternative device drivers...


Not with the current drivers.  The current serial drivers generate one
interrupt per character.  At 38.4, this soaks up quite a bit of CPU.
While the Zilog controller is physically capable of high speeds, I
don't know if NeXT's implementation is capable of it (NeXT claims it
cannot do LocalTalk on their serial hardware, and that could be a
reason...).  Furthermore, the hardware interface is not documented and
it may not be possible to write your own drivers that won't step on
the toes of NeXT's...

The DSP can function as a serial port that can go up to something like
138kbps.  Yrrid sells an LKS called TTYDSP that makes the DSP into a
third serial port (DISCLAIMER: I was a beta-tester for TTYDSP) that
will go up to 138k.


I think you best bets would be a NeXTbus card with a serial interface,
a SCSI<->serial interface of some kind, or an ethernet<->serial
interface (do any terminal servers do 250kbps?).


andrew
-- 
andrew@cubetech.com     | "We shall not cease from exploration
Andrew Loewenstern      |  And the end of our exploring
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