Re: Plus/4 RS232 woes

From: André Fachat <afachat_at_gmx.de>
Date: Wed, 05 Sep 2018 18:51:51 +0200
Message-ID: <165aaa5b458.27e0.b4d1f2b66006003a6acd9b1a7b71c3b1@gmx.de>
Am 5. September 2018 4:39:09 PM schrieb Jim Brain <brain@jbrain.com>:


> Most people did not make the connection that 1.8432/16 = 115200.
> However, I think Commodore and Apple did understand.  At the time the
> devices came out, 115200 was not a bps rate in general use, and line
> drivers at the time would have struggled to keep up and adhere to the
> standard. 

Indeed 115200 bps is more than 11k bytes per second, which leaves about 100 
cycles per byte at 1MHz.

Without a working way to stop the other side from sending (see the previous 
RTS discussion here) there is not much left to do other things. .

You'd probably had best to use an interrupt to receive a byte to be able to 
do other things in parallel. That would take maybe 30 to 40 cycles, taking 
almost half the CPU.

André

(Calculations done in head so only estimated :-))
Received on 2018-09-05 19:00:04

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