🚀 go-pugleaf

In article <9001061902.AA03244@ucbvax.Berkeley.EDU> 11TSTARK@GALLUA.BITNET (Timothy Stark) writes:
>
>     I want transfer my files between my Amiga 500 and TI-99/4A computers.
>
>
>       Amiga 500 Connector                  TI-99/4A RS232 Connector
>
>             1  GND Ground                     1  GND Ground
>             2  TXD Transmit Data              2  RD  Receive Data
>             3  RXD Receive Data               3  TX  Transmit Data
>             4  RTS Request to send            5  CTS Clear to send
>             5  CTS Clear to send              6  DSR Data Set Ready
>             6  DSR Data Set Ready             7  GND Ground
>             7  GND Ground                     8  DCD Detect Carrier
>             8  DCD Carrier Detect             20 DTR Data Terminal Ready
>             9  +12 12 volts
>             10 -12 12 volts
>             11 AUDO Audio output
>             18 AUDI Audio input
>             20 DTR  Data Terminal Ready
>             22 RI   Ring Indicator
>
>My TI-RS232 Manual says that DTR is require for operation why that it
>refuse to work!!
>
>I will consider to connect null modem cable with 4 wires: RXD, TXD, DSR,
>and DTR. Perhaps It will work well.

Null-modem cables are made like this:

	Amiga			Amiga

	1	---------	1			Shield GND
	2	---\ /---	2			Transmit Data (TXD)
		    X
	3	---/ \---	3			Receive Data (RXD)
	7	---------	7			Signal GND

Only pins 2,3 & 7 are necessary to operate successfully. Some equipment like
Ganhalf's GLMs allow you to use only 2 & 3. Connect pins 1 to the shield of
the cable only if excessive noise is picked up.

So we see that what one computer transmits through the TXD pins gets received
by the RXD pin of the other computer. Your TI computer has already switched
these two signals on its port, therefore the null-modem cable will not work
here.

A straight 25 cable will not work either, because signals 6 and 20 also have
to be switched when used. Just don't connect them if you want no hassles. But
if you insist connect them like pins 2 & 3:

	6	---\ /---	6		Data Terminal Ready (DTR)
		    X
	20	---/ \---	20		Data Sender Ready (DSR)

Valentin
-- 
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