Chapter 10
Peripherals for your +3

Subjects covered...

	Cassette unit
	Printer
	Additional disk drive
	Joystick(s)
	VDU Monitor
	Amplifier
	Serial devices
	MIDI device
	Auxiliary interface
	Expansion devices

The +3 is capable of operating with a wide range of add-ons
(peripherals) such as joystick(s), printer, cassette unit, etc. This
section contains all the information necessary to connect these.


Cassette unit

Programs may be loaded from, or saved to tape instead of disk, (the
commands which instruct the computer to direct data to and from disk
or tape were explained earlier in this manual).

To connect your cassette unit to the +3, you will require a suitable
interconnecting lead, wired as follows...


            TAPE/SOUND socket on the +3                     Cassette unit

                                                            To EAR socket
                         Input                                 ___
                         (EAR)                             __ /   |____
                           |                              / _|    |____()
                           |       ___                   / /  \___|
             ___    _      v      |   --_               / /
 Input (EAR)    \/ | |     _ _____|      -.------------' /
                   | |  ()[_[_____|       |-------------<
Output (MIC) _/\   |_|  ^       | |     _-^------------. \  To MIC socket
                    |   |       | |___--                \ \    ___
GND (common) _______|   |       |                        \ \_ /   |____
                      Output   GND                        \__|    |____()
                       (MIC) (common)                         \___|

                                                              (red)


You will see that the shaft of one of the jack plugs is divided into 3
separate metal sections - this is the plug that should be inserted
into the socket marked TAPE/SOUND at the back of the +3.

The shafts of the other two jack plugs are divided into only 2
separate metal sections - these are the plugs that should be inserted
into the sockets on your cassette unit marked MIC and EAR. (On most
commercially available leads, the plug for the MIC socket is coloured
red.)

(On some cassette units, the MIC socket may be labelled COMPUTER IN or
INPUT. Likewise, the EAR socket may be labelled COMPUTER OUT or
OUTPUT.)

It is important to remember that the successful transfer of programs
to and from tape is largely dependent on the correct setting of the
LEVEL or VOLUME control on your cassette unit. If you cannot load or
save program easily, try experimenting with different LEVEL control
positions until the optimum setting is found. If you cannot seem to
load or save any programs at all, try reversing the plugs to the MIC
and EAR sockets on your cassette unit.

Details of tape operation will be found in chapter 4 and chapter 8
parts 20 and 27.


Printer

The +3 may be used with any Centronics compatible parallel printer. We
would particularly recommend the AMSTRAD DMP range of printers
(e.g. models DMP2000, DMP3000, DMP3160 or DMP4000) for use with the
+3.

If you intend to connect the AMSTRAD DMP2000 to the +3, simply use the
interconnecting lead provided with the printer.

If you wish to use any other Centronics compatible printer, you will
require the AMSOFT PL-1 printer interconnecting lead.

Connect the end of the lead which is fitted with the flat
edge-connector plug, into the socket marked PRINTER at the back of the
+3.

Connect the other end of the lead (which is fitted with a Centronics
style plug) into the socket on the printer. If your printer is
equipped with security clips at each side of the socket, these may be
clipped into the cut-outs at the side of the printer plug.


  17  16  15  14  13  12  11  10   9   8   7   6   5   4   3   2   1
  .-. .-. .-. .-. .-. .-. .-. .-. .-. .-. .-. .-. .-. .-. .-. .-. .-.
|^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^|^^^^^^^^^^^^^^^^|
|____________________________________________________|________________|
  `-' `-' `-' `-' `-' `-' `-' `-' `-' `-' `-' `-' `-' `-' `-' `-' `-'
  35  34  33  32  31  30  29  28  27  26  25  24  23  22  21  20  19

                          (viewed from rear)

                            PRINTER socket


PIN	FUNCTION	PIN	FUNCTION
	______
1	STROBE		19	GND
2	D0		20	GND
3	D1		21	GND
4	D2		22	GND
5	D3		23	GND
6	D4		24	GND
7	D5		25	GND
8	D6		26	GND
9	D7		27	not used
10	not used	28	GND
11	BUSY		29	not used
12	not used	30	not used
13	not used	31	not used
14	GND		32	not used
15	not used	33	GND
16	GND		34	not used
17	not used	35	not used
18	does not exist	36	does not exist


Although there are only 34 terminations at the +3's PRINTER socket,
the pins are numbered 1...17 and 19...35 (with 18 and 36 non-existent)
for equivalence with the Centronics socket on the printer itself...

Note that printers for use with the +3 must generate their line feeds
internally. If you experience problems with printer line feeds, try
adjusting the appropriate 'DIP switch' inside your printer. (On the
AMSTRAD DMP range of printers, DIP switch DS1-4 controls the line feed
setting.)


The +3 may also be used with most serial printers conforming to the
RS232 standard. It is recommended that inexperienced users should not
attempt to experiment with serial interface connections. You should
obtain a suitable computer-to-serial printer lead from your Sinclair
dealer, and you should always follow the printer manufacturer's
installation and operation instructions.


A serial printer should be connected to the RS232/MIDI socket at the
back of the +3.

Details of (parallel and serial) printer operation will be found in
chapter 8 parts 21 and 22.


Additional disk drive

The AMSTRAD model FD-1 may be added to the +3 system as an additional
disk drive.

Thanks to the versatility of +3 BASIC, you can do all necessary file
maintenance, copying, erasing, etc., on a single disk drive. However,
a second drive will certainly speed up these operations and reduce the
scope for accidents.

To connect the FD-1 to the +3, you will require the AMSOFT DL-2 disk
interconnecting lead.

Connect the end of the lead which is fitted with the larger
edge-connector plug, into the socket marked DISK B: at the back of the
+3.

Connect the other end of the lead which is fitted with a smaller plug,
into the socket at the back of the FD-1 disk drive.

Important - Before connecting or disconnecting the additional disk
drive, make sure that any disks are removed from both drives, and that
the system is switched off. If connections are altered while the
system is on, it is likely that the system will crash, losing any
program or data. Always save any valuable programs before meddling
with connections!

When the FD-1 is connected to the +3, first switch on the FD-1 (using
the slide switch at the back of the disk drive), then switch on the +3
(by plugging in the PSU). Both the green and red indicators on the
front panel of the FD-1 should be illuminated. The two-drive system
will then be ready to operate.


   2   4   6   8  10  12  14  16  18  20  22  24  26  28  30  32  34
  .-. .-. .-. .-. .-. .-. .-. .-. .-. .-. .-. .-. .-. .-. .-. .-. .-.
|^^^^^^^^|^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^|
|________|____________________________________________________________|
  `-' `-' `-' `-' `-' `-' `-' `-' `-' `-' `-' `-' `-' `-' `-' `-' `-'
   1   3   5   7   9  11  13  15  17  19  21  23  25  27  29  31  33

                          (viewed from rear)

                            DISK B: socket


PIN	FUNCTION	PIN	FUNCTION
	_____
1	READY		18	GND
				________
2	GND		19	MOTOR ON
	_____________
3	SIDE 1 SELECT	20	GND

4	GND		21	not used
	_________
5	READ DATA	22	GND
				______________
6	D4		23	DRIVE SELECT 1
	_____________
7	WRITE PROTECT	24	GND

8	GND		25	not used
	_______
9	TRACK 0		26	GND
				_____
10	GND		27	INDEX
	__________
11	WRITE GATE	28	GND

12	GND		29	not used
	__________
13	WRITE DATA	30	GND

14	GND		31	not used
	____
15	STEP		32	GND

16	GND		33	not used
	_______________
17	DIRECTIONSELECT	34	GND


Details of two-drive operation will be found in chapter 8 parts 20 and
27.


Joystick(s)

We recommend that you use the Sinclair SJS range of joystick(s) with
the +3. Other types of joystick (e.g. Atari) will not operate
directly, as their connecting plugs are wired differently.

There are two joystick sockets at the left-hand side of the +3. In
general, games use the JOYSTICK 1 socket.

If a program offers you a choice of joystick types, then choose the
'Interface Two' (or 'Sinclair') option (as the +3's joystick circuitry
is designed to work exactly like the Interface Two).

It is safe to plug in (or unplug) a joystick while the +3 is switched
on.


PIN     FUNCTION

1       not used
2       common			JOYSTICK 1 and JOYSTICK 2 sockets
3       not used                      _____________________
4       fire                         /  1   2   3   4   5  \
5       up                           \  o   o   o   o   o  /
6       right                         \   6   7   8   9   /
7       left                           \  o   o   o   o  /
8       common                          \_______________/
9       down


VDU Monitor

The +3 can use a monochrome or colour VDU monitor (or a French
standard PERITEL TV) instead of (or in addition to) an ordinary TV. If
the monitor that you wish to use isn't quoted as being Spectrum +3
compatible, then the chances are you'll have to buy a lead for it
(contact your Sinclair dealer).

A VDU monitor (or PERITEL TV) should be plugged into the RGB/PERITEL
socket at the back of the +3.


PIN	FUNCTION
				      RGB/PERITEL socket
1	+12V				    __   __
2	GND				  _- |___| -_
3	audio out			 /  7     6  \
	______________			/   o     o   \
4	composite sync			| 3    8    1 |
5	+12V				| o    o    o |
6	green				\  5       4  /
7	red				 \ o   2   o /
8	blue				  -_   o   _-
					    `-----'

When using a monitor, some provision may have to be made for sound (if
required). If the monitor has an audio input, then this should be
connected either to pin 3 of the RGB/PERITEL socket or to the
TAPE/SOUND socket at the back of the +3. If the monitor is not capable
of producing sound, then an external amplifier will have to be
used. See the next paragraph for further details.


Amplifier

The +3 normally reproduces sound through the TV set it is connected
to. However, if a VDU monitor is being used, or if you would like to
record or amplify the sound further, then a sound signal is available
from the TAPE/SOUND socket at the back of the +3. This is a 3.5mm jack
socket producing 200mV pk-pk at approximately 5 Kohms impedance. When
using an amplifier, it is worth remembering that if you have connected
a cassette unit to the +3, the tape 'load' and 'save' signals are also
fed to the TAPE/SOUND socket (and therefore the amplifier's volume
control should be turned down when performing these operations).

Another point to note is that the level of sound produced by the BEEP
command is set to be the same as that of all three channels of PLAY
running at the same time. In practice, this means that BEEP will sound
quite a lot louder than PLAY (which may cause problems if sound levels
are critical).

It is safe to plug in (or unplug) an amplifier, tape recorder,
etc. into the TAPE/SOUND socket while the +3 is switched on.


                         Input
                       (not used)
                           |
                           |       ___
             ___    _      v      |   --_
  (not used)    \/ | |     _ _____|      -.___________
                   | |  ()[_[_____|       |___________
Audio output _/\   |_|  ^       | |     _-'
                    |   |       | |___--
GND (common) _______|   |       |
                      Audio    GND
                      output (common)

		    TAPE/SOUND socket

Details of the +3's sound facilities will be found in chapter 8 part
19.


Serial devices

To connect any serial device to the +3, you will require a Spectrum +3
serial lead - available from your Sinclair dealer.

If you wish to wire-up your own, then the connections are as
follows...


PIN	FUNCTION

1	GND			    ___________________________
2	TXD			 __|   6   5   4   3   2   1   |
3	RXD			|__   ### ### ### ### ### ###  |
4	DTR			   |___________________________|
5	CTS
6	+12V				   RS232 socket


Details of serial operations will be found in chapter 8 part 21.


MIDI device

Although the +3's MIDI (Musical Instrument Digital Interface) socket
shares the same socket as the RS232, you will need a different lead
for it (available from your Sinclair dealer). The lead should be
connected into the 'MIDI IN' socket on your synthesiser, drum machine,
etc. There is no provision for the +3 to receive MIDI data - it can
only act as a source. No setting up of the MIDI is necessary before
use (except the inclusion of the 'Y' parameter within the PLAY command
to turn it on).


PIN	FUNCTION

1	RETURN			    ___________________________
2	not used		 __|   6   5   4   3   2   1   |
3	not used		|__   ### ### ### ### ### ###  |
4	not used		   |___________________________|
5	DATA OUT
6	not used			    MIDI socket


Details of MIDI operations will be found in chapter 8 part 19.


Auxiliary interface

The AUX (auxiliary interface) socket supports two input lines (pins 2
and 5) and two output lines (pins 2 and 4). The I/O lines are driven
by 1488 and 1489 line driver chips which are, in turn, connected to
the I/O lines of the AY-3-8912 (see the manufacturer's data sheet for
this device). Basically, register 16 of the AY-3-8912 controls eight
I/O lines, the bits are designated as follows...


BIT	SIGNAL

0	AUX pin 2 (out)
1	AUX pin 4 (out)
2	RS232 pin 5 (CTS out)
3	RS232 pin 3 (RXD out)
4	AUX pin 3 (in)
5	AUX pin 5 (in)
6	RS232 pin 4 (DTR in)
7	RS232 pin 5 (TXD in)


Using software control loops, the I/O lines could be driven as a
second RS232 port (in the same way as the RS232/MIDI socket is driven
using bits 2, 3, 6 and 7). Alternatively, the I/O lines could be used
to drive, for example, a robot or some other external device.


PIN	FUNCTION

1	GND			    ___________________________
2	OUTPUT BIT 0		 __|   6   5   4   3   2   1   |
3	INPUT BIT 4		|__   ### ### ### ### ### ###  |
4	OUTPUT BIT 1		   |___________________________|
5	INPUT BIT 5
6	+12V				    AUX socket


Expansion devices

The +3 can connect to a very wide range of peripherals via the
EXPANSION I/O socket at the back of the machine. Although this socket
is much the same as on the old-style Spectrum 48K, there is no
guarantee that a device which ran correctly on a Spectrum 48K will run
on a +3. You should, therefore, before you purchase any expansion
device or add-on, verify that it will work with the +3, and not just
with a 48K Spectrum.

+--------------------------------------------------------------------+
| WARNING - It is very dangerous indeed to plug in (or unplug) any   |
| device from the EXPANSION I/O socket while the +3 is switched on - |
| you will probably damage both the +3 and the expansion device if   |
| you do so.                                                         |
+--------------------------------------------------------------------+


U 27  26  25  24  23  22  21 	       8   7   6   5   4   3   2   1
  .-. .-. .-. .-. .-. .-. .-.         .-. .-. .-. .-. .-. .-. .-. .-.
|^^^^^^^^^^^^^^^^^^^^^^^^^^^^ /////// ^^^^^^^^^^^^^^^|^^^^^^^^^^^^^^^^|
|____________________________ /////// _______________|________________|
  `-' `-' `-' `-' `-' `-' `-'         `-' `-' `-' `-' `-' `-' `-' `-'
L 27  26  25  24  23  22  21 	       8   7   6   5   4   3   2   1


			EXPANSION I/O socket


PIN	UPPER ROW (U)	LOWER ROW (L)

1	A15		A14
2	A13		A12
3	D7    __	+5V
4	ROM 1 OE	not used
5	D0		GND
6	D1		GND
7	D2		CK
8	D6		A0
9	D5		A1
10	D3		A2
11	D4		A3
	___
12	INT		not used
	___
13	NMI		GND
	____		      __
14	HALT		ROM 2 OE
	____		     __
15	MREQ		DISK RD
        ____		     __
16	IORQ		DISK WR
	__		________
17	RD		MOTOR ON
	__		_____
18	WR		BUSRQ
			_____
19	not used	RESET
	____
20	WAIT		A7
21	+12V		A6
22	-12V		A5
	__
23	M1		A4
	____
24	RFSH		not used
25	A8		BUSACK
26	A10		A9
27	RESET		A11


Details of the +3's hardware will be found in chapter 8 part 30.