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V~S
CABLING:
My cable run between the two computers was 100 feet, since they are in different rooms. I went to lengths to make sure it was wired for other uses. At 100 feet, V~S and 9600 baud null-M works great. The reason I want null modeming is that I can transfer any type file from anywhere on the ST hard disk to/from any useable disk I have on the A8. There are limits to what V~S can access.

FIGURE 1a:Simplest 4 wire setup
The simplest cable is an A8 SIO cable half, connected to an adapter using either 1 or 2 chip versions, and then a 4 wire phone cable to the ST ending with a DB25 female connector. Note that if you go through a switch box, then you will need a gender changer too.
I did not show wire colors on the A8 SIO cable as these change.
I added an LED and resistor(220 ohm) between +5 and gnd on the A8 side, so I'd know when it was powered, and a .01uF cap from gnd to +5.


FIGURE 1b:An overview of my setup


FIGURE 2a:My setup is very modular
I wanted maximum flexability until I could decide how I want the setup to operate. Options are:
: EASIO-S cable to DB25F/M project hood with adapter and 2 connectors, to the phone cord wired to a DB25F hood(My Choice).
: EASIO-S cable to DB25F / 8P8C adapter with V~S chip(s) wired into it.
: Just a small box with the adapter board, an SIO cable and the phone cable directly wired in eliminating all of the DB25 connectors.


FIGURE 2b:Using 8 wire phone cable
This is wired for null-M by default. This is the version that would plug into a switch box, through an adapter if you don't want to rewire the box. *I have used gray for the actual white wire.

I chose to use 8 wire telephone cable as thats the minimum needed for null modeming. But, compatible V~S uses pin 22 on the ST that null modeming does not. So 9 wires would have been better. Since I need a switchbox on the ST side anyway, I'll just rewire it to make the changes. Also, 8 wire phone cable can be difficult to solder-the wires break easily. So using 8P8C plugs and an 8P8C to DB25 adapter would be easier.


FIGURE 2c:Wiring an adapter for the ST side


FIGURE 2d:How the ST Switchbox is rewired for both with 8 wire cable.

A8 null modem wired cable plugs into A. Nothing plugs into B-cover with tape. The B connections are made by moving wires from B to A: 2 to 3, 3 to 2, 7 to 7, and 22 to 6.



FIGURE 2e:The rewired ST switchbox.
This is a pic of the switchbox, connector A on the left(the cable plugs in here), connector B on the right. The 4 green wires on the left were moved from B to A. C(modem) is under A, and the ST common is under B.


SWITCHBOXES SETTINGS:
For Null Modeming:1A+2A+3A
For Virtual SIO:1B+2B+3B
Standard A8 peripheral use:1A, 2 & 3 don't matter.
ST Modeming:3C, 1 & 2 don't matter.
If other R: ports on the 850 are compatible, then V~S might be able to be plugged into one of them for Null-M, leaving the R1: port free for a modem. If used with an 850 and an atr8x00, then the 850 could do R1: Null-M while the ATR has a modem.

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