CHAPTER 3

HARDWARE CONNECTIONS


This chapter covers the inter-connections between your communications hardware
and your computer.  You must make these connections properly before this program
can be used effectively. This software will not work if your hardware is not
correctly interfaced.  In most cases, you will use this program with a modem.
Therefore, this chapter will primarily describe the interface in terms of a
modem connection.  If you are connecting directly to another computer or
something other than a modem, the same description will generally apply.

The major purpose of this chapter is to provide you information to connect your
modem to support communications with this program. Therefore, the instructions
in this chapter will promote the setting of all control or handshake connections
between the modem and the computer to the "on" state.  This will reduce the
potential problems in getting the basic receiving and transmitting functions
operational.  After you have been able to satisfactorily perform receiving and
transmitting, the control connections can be re-configured to support more
advanced features which require handshaking.

If you use a Brand W cable to connect a Brand X external modem to a Brand Y
serial card in a Brand Z computer, you should not expect to automatically
achieve all of the correct connections just by plugging everything together. 
This chapter will provide broad guidelines so you can determine how to connect
the signal lines for communications.  Some specific information will be
presented on common hardware peripherals.  However, it is impossible to
individually describe all of the connections for all of the possible
combinations of modems and serial cards in this manual.  It is your
responsibility to inter-connect your equipment with your computer.

In some cases, you can perform the hardware installation by simply plugging a
card into the computer.  In other cases, it will require the preparation of a
special cable or the modification of an existing cable.

If you have an external modem and have already used it to successfully
communicate with other systems, then you probably have most of the required
interfacing competed.  However, you may still have some missing wiring
connections which are necessary to support all of the features offered by this
program.  There may also be some unterminated connections which can cause noise
pickup and erratic operation.


INTERNAL PLUG-IN MODEM CARDS

If you have an internal plug-in modem card, all you have to do is set the card
switches (if any) according to the modem instruction manual, attach any cables
supplied with the card, and plug the card into the computer  (Be sure the
computer power is turned off first). If you have a prometheus ProModem 1200A,
set switch 3 ON.  If you have a Hayes Smartmodem 1200A, set switch 2 DOWN.  If
you have a Cermetek Applemate 1200, set SW10 closed.

Some internal modems consist of two cards.  Remember which slots you have used
for the modem cards so you can specify them when you run the INSTALL program. 
If you have an internal plug-in modem, skip over to Chapter 4 where the various
modems are described.  Read the section which covers your modem.


INTERNAL SERIAL OR COMMUNICATIONS CARD.

If you are using an external modem with an internal plug-in serial or
communications card, read the serial card  instruction manual to determine how
the default baud rate is set.  Usually there are switches or jumpers on the card
provided for setting the default baud rate.  Some card also have switches or
jumpers to set the default communications parameters (number of data bits,
number of stop bits, parity).  Unless you have some other preference, set the
switches for 8 data bits, 1 stop bit, and no parity.

Although some cards are supplied with utility programs to set the communications
parameters, these settings are lost when the computer is turned off.  There is
no need to run any of these utility programs before you run MODEM MGR.  One
exception is the utility program used with cards which can store the setting
permanently in non-volatile RAM.  If your card has non-volatile RAM, run the
utility program to set and save the default communications parameters.

Perform the following steps before installing the plug-in serial card.

1)  Set the card switches or jumpers to the default baud rate

2)  Set the card switches or jumpers for the desired default number of data
bits, number of stop bits, and parity.  Some cards do not have the capability to
permanently set these communications parameters.  MODEM MGR will set the
defaults for those cars when it is run.

3)  Verify the card is configured for a "modem" connection and not a "printer"
connection.  Some cards have a switch, jumper, or plug to make this choice,
while other cards may provide a different cable connector for each type of
connection.

4)  Read the individual description pertaining to your serial card in Chapter 4
and set the handshake switches or jumpers accordingly.

If you have a multi-function card which combines several functions (serial,
parallel, clock) on one card, follow the instructions provided with the card to
define which slot the serial function has been assigned to.  The earlier
discussion on internal serial cards applies to the serial function of these
cards also.  Read the individual description for your multi-function card in
Chapter 4.


EXTERNAL MODEMS

For purposes of discussion in this manual, external modems will be classified
into three major types.

1)   "Smart" modems.  These are modems which have a built-in processor and
firmware to control all the major modem functions. These modems accept character
string commands for automatic baud rate and communication parameter selection,
dial, answer, hangup, and status reporting.  The Hayes Smartmodem and dozens of
"Hayes-compatible" modems are in this category.  The Novation Smart CAT and the
Prometheus Promodem 1200 modems are also "smart" modems.

2)  Auto modems.  These are modems which can answer and hangup automatically,
but do not have dialing capability.  Some functions must be set with manual
switches.  The Vadic 3451 and Novation Auto-CAT are in this category.

3)  Dumb modems. These are modems without dialing capability.  You must manually
control these modems with switches to answer, go online, or hangup.  Most
acoustic modems are in this category.

Auto and dumb modems will also be referred to as "non-smart" modems.

Set the baud rate switch on the modem (if any) to match the baud rate of your
serial card.  If your modem has a switch to control the carrier detect output
(DCD), set it so the carrier detect signal is always on.  IF your modem has a
switch to control the response to the data terminal ready (DTR) signal from your
computer, set it so DTR is always on and the modem ignores the signal from the
computer. Later you may wish to set these switches differently, but set it as
described for now.


DB-25 CONNECTOR

Most modems and serial card cables use a D-shaped connector approximately 1-1/2
inches wide called a DB-25 connector.  This connector has become a standard for
serial connections.  THe DB-25 connector has two rows of contacts which are
either all pins or all sockets.  One row has 13 contacts and the other row ahs
12 contacts. Often the contact numbers (from 1-25) are embossed on the face of
the connector.

In some connectors, several of the contacts may be missing.  THe connector has
the capability ot handle up to 25 wiring connections. Typically, there are much
less than 25 connections required, so the cable attached to the connector may
have anywhere from three to 25 wires.

A connector with pin contacts is called a "male" connector and a connector with
socket contacts is called a "female" connector.  To mate two connectors
together, one must be a male connector and the other must be a female connector.
 The connecter attached to a cable is sometimes called a plug while the
connector attached to a hardware unit is sometimes called a jack.  To avoid
confusion, these tow terms (jack, plug) will not be used again in this manual.

Some hardware units do not use the DB-25 connector.  For example, the Apple //c
and some serial cards use a round 5-contact DIN connector.  The Apple 300 and
1200 modems use a nine-contact DB-9 connector.  THe IIGS and Apple Personal
Modem use 8-pin mini-DIN connectors. If you are using equipment with any of
these connectors, refer to the description of your hardware unit in Chapter 4 to
determine which pins should be  interfaced.


CABLES

There are two common types of cables used with DB-25 connectors. One type
consists of individual wires bundled together inside a round sleeve.  (sometimes
a metallic braid or sheath encloses the wires for shielding).  The other common
type of cable is a flat ribbon cable.  The physical characteristics of a ribbon
cable are such that connections are made straight across from connector to
connector without crossovers. In other words, each wire connects the contact
having the same number on both connectors.  The non-ribbon type of cable can be
connected so the wires terminate at any contact desired.  The wires can even be
looped back to terminate both ends at different contacts on the same connector.

If you inspect the DB-25 connector and cable, you can sometimes visually
determine which contacts are connected.  If a ribbon cable has 25 wires then all
contacts i through 25 are probably connected. If the ribbon cable has only 15
wires, then contacts 1 through 8 and 14 through 20 are probably connected.  If
the connector has less than 25 contacts installed, you can probably assume the
installed contacts are all connected.  For example, if the connector has only
pins 1, 2, 3, 4, 5, 6, 7, 8, and 20, those nine contacts are probably all
connected.  It is easy to determine which pins are installed on a male
connector, while you may have to study a female connector carefully to determine
which sockets are installed.

Although there are some exceptions, most external modems have a female DB-25
connector.  Some serial cards are equipped with a short cable terminated in a
DB-25 connector which normally mounts on the rear of the computer.  A longer
cable must be used to connect between this connector and the modem connecter. 
Some serial cards have a  cable which is long enough to run directly to the
modem connector.  If the cable has a male DB-25 connector, it will make with the
female DB-25 connector on the modem.  However, the fact that the two connectors
mate does not necessarily mean the correct signals have been interfaced.

In the remainder of this manual, a connector contact will be referred to as a
pin although it may be either a pin or a socket. We will try not to use the
signal or device names defined in the RS-232-C interface standard when
discussing serial card connections because it increases the confusion and some
of the names become meaningless when the communications software defines the
control functions.

Instead, we will refer to connector pin numbers because the ultimate problem
will be to determine which pin to make a connection to.  We will use RS-232
names occasionally when we are describing the modem connector.


GROUND (COMMON) CONNECTION

Pin 7 on the DB-25 connector is always used for the signal common or ground
connection.  A wire must always be provided to connect pin 7 on one connector to
pin 7 on the other connector.


DATA LINE CONNECTIONS

Usually the modem DB-25 connector uses pin 2 for data from the serial card
output and pin 3 for data to the serial card input.  If the connector on the
cable from the serial card had pin 2 assigned for serial card data output and
pin 3 assigned for serial card datA input, the two data lines will be properly
interfaced when the connectors are directly mated.

There are some cases where the serial card pin assignments will be reversed. 
That is, the serial card input will be on pin 2 and the serial card output will
be on pin 3.  If the pin assignments are reversed, the data lines will not be
properly interfaced and communications cannot be achieved when the connectors ar
mated directly.  Those serial cards with reversed pin assignments for the modem
function will be mentioned in the description of the individual cards in Chapter
4.

If the pin functions are reversed, then something must be done to correct the
reversal.  There are several ways of doing this:

1)  If the modem has a reversing switch for pins 2 and 3, you may set it to
correct the reversal.

2)  If the cable connector has removable pins, you may remove the pins from the
connector and re-install them to correct the reversal. You may need a special
extraction tool to remove the pins and you may have to perform some disassembly
and re-assembly of the connector body.

3)  If the cable is non-flat cable with separate individual wires ,you may be
able to cut and cross-splice the two wires.  Be sure to tape the connections so
the spliced conductors are not exposed to potential short-circuits.

4)  If the cable is flat ribbon cable, you may be able to strip the individual
wires out of the cable and cross-splice them.  Be sure to tape the connections
so the spliced conductors are not exposed to potential short-circuits.

5)  You may use an adapter cable with cross-over connections in series between
your cable and modem.

6)  You may install a break-out box or RS-232 tester in series between your
cable and modem.  This device allows jumpers or provides dip switches to correct
reversal.

7)  You may use a "smart" cable. This uses an electronic device built into the
connector to sense and correct a reversal.

After you have interfaced pins 2, 3, and 7 correctly, you may be able to
communicate with only these three signals connected.

If you have a three-conductor cable, you can sometimes use it successfully to
connect your modem to your serial card if all of the serial card control inputs
are held "high" by internal pull-ups and the modem does not require a "high"
input from your seria lcard. However, if you use a cable which provides only
three connections, you will not be able to use carrier control. ALso, if you
have a "non-smart" modem, you will not be able to hangup under program control.


SERIAL CARD CONTROL INPUTS

Most serial cards have a handshake or control input which must receive a "high"
or "on" or "asserted" control signal in order to enable the serial card
receiver.  Instead of using RS-232 terminology, we will call this input the
receiver control input. Many serial card also have another control input which
must be set "high" in order to enable the serial card transmitter.  We will call
this the transmitter control input.  If your data lines are properly interfaced
but you cannot receive and/or transmit data to the modem, you may have a "low"
control signal on one of these control lines.

Those control inputs usually receive a "high" signal from the modem when valid
two-way communications can be conducted. If these control lines are not
connected to the modem or are connected to the wrong pins on the modem
connector, they may be forced to the "low" state which disables communications
to or from the serial card.

In some serial cards, the control lines are wired internally to pull-up circuits
so they are forced "high" when there are no external control wires attached. 
THis design enables two-way communications with the modem even if the control
signals from the modem are not wired to the card.  If an external control signal
is wired to the card connector, it will over-ride the pull-up circuit.

Some serial cards provide a switch or jumper which allows you to disconnect the
control input from the card DB-25 connector and connect it to a pull-up circuit.
 THis design forces the control line "high" regardless of the signal applied to
the control connector pin.

In some cards, there are no pull-up circuits provided so you must wire the input
to a modem or serial card output which is either permanently "high" or goes
"high" whenever valid communications can be performed.

The receiver and transmitter control input pins are listed in the description of
the various serial cards in Chapter 4.  If your serial card has one or both of
these inputs they must be "high" or pulled-up when you wish to conduct two-way
communications.

If you enable carrier control (by the INSTALL program), the seria lcard receiver
control input will be used by this program for carrier status.  If you wish to
implement carrier control, there carrier-detect signal from the modem must be
wired to the serial card receiver control input.  If you don't  want carrier
control, this control input must be kept permanently "high".  Chapter 11
describes the advantages and disadvantages of carrier control and provided
instructions on properly interfacing the modem carrier-detect output to the
receiver control input.

MODEM MGR requires the transmitter control input always be kept "high".

The control inputs are not always assigned to the same pin on the serial card
DB-25 connector.  The assigned pins are listed in the individual descriptions of
the serial cars in Chapter 4.


SERIAL CARD CONTROL OUTPUT

Most serial cards have a control output which is set "high" or "low" by the
software. MODEM MGR usually sets this output permanently "high" except when a
non-smart modem is used.  The only way to hangup some non-smart modems under
program control is to force the modem DTR control input (usually pin 20 on the
modem DB-25 connector) to "low".  If you have a non-smart modem which supports
this feature, refer to the descriptions of your serial card to determine which
pin on the serial card to connect to the modem DTR pin.

If you are using a "smart" modem, this program handles hangup in a different
manner and does not use the serial card control output, so this serial car
output will be set "high".  It can be connected to the modem DTR input or used
as a "high" source for any other pin which must be kept "high".


MODEM CONTROL INPUT

As mentioned in the previous section, some modems have a DTR control input
(usually on pin 20 of the DB-25 connector) which must be kept "high" to enable
the modem to send or receive.  The status of this input is sometimes displayed
as a "TR" or "DTR" indication on the modem front panel.  Earlier, it was
mentioned that if there is a modem switch which allows the modem to disconnect
this signal from its connector and internally set it "high", then it should be
set "high".  If you can never send or receive with the modem, insure this input
is "high".  If it is "low", set the switch or remove the external connection
which is causing the "low" condition.


SERIAL CARD INPUT CONTROL PROBLEMS

If you suspect an incorrect handshake or control input is preventing you from
conducting two-way communications with your modem, try to determine if the modem
is possibly functioning in at least one data direction.  The modem may not be
currently capable of two-way communications, but may be capable of either
transmitting or receiving.

Many modems have front-panel lights which indicate when data is sent or
received.  Run this program and be suer the baud rate matches the modem baud
rate.  Enter the terminal mode by typing [RETURN] after the "Command? -->"
prompt.  Type some characters on your keyboard. If your modem has a "SEND" or
"SD" light and it blinks, your are transmitting to the modem and you can
concentrate on solving the receiving problem.

Some modems have an echo or test mode which will send characters to your
computer.  Initiate this test mode and see if your computer is receiving
characters from the modem.  If the modem test characters are displayed on your
screen, you can concentrate on solving the transmitting problem.


ENABLE RECEIVER

If you are unable to receive from the modem, the receiver control input on your
serial card is probably set "low".  Use the following methods to force the
serial card receiver control input to "high" or "on" state.

1)  Refer to your serial card instruction manual or the description of your
serial card in Chapter 4.  Determine if you can set a switch or remove a jumper
to disconnect the serial card receiver control input from the DB-25 connector
and set it permanently "high".  If so, perform the steps required to disconnect
it and set it "high".

2)  If you cannot disconnect the receiver control input from the connector,
refer to the description of your serial card in Chapter 4 and determine which
pin the receiver control input is on and whether it has na internal pull-up
circuit or not.

3)  If your serial card receiver control input has an internal pull-up circuit,
remove the modem wire connection to this pin, if possible.

4)  If you cannot remove the wire, or if your serial card receiver control input
does not have an internal pull-up, you must wire the pin to a "high"signal. 
Wire it to the carrier-detect output (usually pin 8 on the modem connector) or
to any pin on the modem or serial card which is always "high".  Refer to the
modem and serial card manuals to determine which pins are set permanently
"high."


ENABLE TRANSMITTER

If you are unable to transmit to the modem, there serial card transmitter
control input is probably set "low".  Use the following methods to force the
serial card transmitter control input to the "high" or "on" state.

a)  Refer to your seria lcard manual or the description of your serial card in
Chapter 4.  Determine if you can set a switch or remove a jumper ot disconnect
the serial card transmitter control input from the DB-25 connector and set it
permanently "high".  If so, perform the steps required to disconnect it from the
connector.

b)  If you cannot disconnect the transmitter control input from the connector,
refer to the description of your serial card in Chapter 4 and determine which
pin the transmitter control input is on and whether it has an internal pull-up
circuit or not.

c)  If your serial card transmitter control input has an internal pull-up
circuit, remove the modem cable wire connection to this pin, if possible.

d)  If you cannot remove the wire, or if your serial card transmitter control
input does not have an internal pull-up, you must wire the pin to a "high"
signal.  Wire it to a pin on the modem or seria lcard which is always "high". 
Refer to the manual on the modem and serial card to determine which pins are set
permanently "high".


UNTERMINATED CONTROL (HANDSHAKE) WIRES

Check your cable to insure that all cables connected to the transmitter or
receiver control inputs on your serial card are connected to a control source at
the modem end.  If any control wire is not connected to a control output at the
modem end, terminate it on a "high" signal or remove the wire.

Unterminated wires behave like antennas which receive noise spikes from the data
lines.  Data reception can be momentarily disabled by the noise transients. 
This is sometimes so severe that no characters can be received.  In other cases,
the symptoms are subtle and you will not notice any problems at low baud rates
or when communications involve mostly receiving or mostly transmitting. However,
at high baud rates with simultaneous receiving and transmitting, some incoming
characters will be lost.

The use of a shielded cable will not prevent this problem because the source
data wires and the victim handshake wires will still be bundled together within
the shield.  This problem will exist even with a pull-up circuit on the serial
card because most simple resistor pull-up circuits do not provide adequate noise
immunity when a long unterminated wire is connected.

Unterminated wires often occur when a break-out box or RS-232 testes is inserted
between the modem and the serial card.  THis type of tester allows lines to be
opened.  THis is necessary for testing or trouble-shooting, but be sure to
remove the tester or terminate all control lines after the testing is completed.

The importance of avoiding unterminated handshake lines cannot be over-stressed.


PULSE DIALING CONTROL

Some auto modems have an input which allows control of the modem hook switch. 
IF this input is compatible with the ][+ or //e game prot annunciator TTL
output, this output can be toggled by the computer to provide pulse dialing. 
For example, the Novation Auto-CAT modem has this signal on pin 25 of the modem
DB-25 connector and the Novation J-CAT modem has this signal on pin 7 of the
modem edge connector.  If this pin is connected to pin 14 on the game port I/O
connector and the auto modem driver is installed, program control of pulse
dialing will be supported.

Some modems require their DTR input (pin 20) be held low while this type of
dialing is being performed.  THe auto modem driver lowers the serial card output
control signal while dialing, so this control signal can be used to control the
auto modem DTR input.


HARDWARE PROBLEMS

After dealing with many cases where receiving and/or transmitting could not be
achieved with this software, we have found the following have been the major
causes:

1)  The modem and serial card were set for different baud rates.

2)  A special modified cable must be used between the modem and serial card.

3)  The switches or jumpers on the serial card were set to the wrong position.

Since these are common problems, you should investigate these possibilities if
you cannot receive and/or transmit.  As we mentioned earlier, it is your
responsibility to inter-connect your hardware to operate properly.  We have
provided you with some information on connecting your communications equipment
and setting the switches or jumpers on your hardware, but we cannot support any
hardware problems you have.  Our support is limited to software problems.

Although we have found that practically all of the communications hardware
available for the Apple // personal computers perform very well, some of these
devices require additional configuration or special cabling before they can be
used in even a simple basic (no carrier control) environment.  If you purchased
two pieces of hardware that will not work together in a simple configuration
until you modify the cabling between them, that last thing you should blame is
the software.