Re: Plus/4 RS232 woes

From: André Fachat <afachat_at_gmx.de>
Date: Mon, 03 Sep 2018 19:04:41 +0200
Message-ID: <165a064bc28.27e0.b4d1f2b66006003a6acd9b1a7b71c3b1@gmx.de>
Am 3. September 2018 18:29:49 schrieb "Mike Stein" <mhs.stein@gmail.com>:

>
> ----- Original Message -----
> From: "André Fachat" <afachat@gmx.de>
> To: <cbm-hackers@musoftware.de>
> Sent: Monday, September 03, 2018 11:06 AM
> Subject: Re: Plus/4 RS232 woes
>
>
>>
>> According to my Rockwell data handbook, if you set RTS inactive via the
>> command register, it disables the Transmitter.
>>
>> Bummer.
>>
> ---
> Why would you 'change your mind' to say you're not Ready To Send while 
> you're actually sending a character, without waiting for the character to 
> be completely sent?

As it seems the ACIA is made for half duplex. Just read some more. The ACIA 
requests to send to the modem, and the modem answers with CTS when the ACIA 
is allowed to send.

This collides with my full duplex understanding of Hardware handshaking. 
Where RTS allows the ACIA to signal to the other side that it is ready to 
receive (request the other side to send) while CTS allows the other side to 
keep the ACIA from sending, so that you can have two ACIAs connected with 
crossed over RTS/CTS connections.

André

>
Received on 2018-09-03 20:00:19

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