Vhen all la well, Insert the diode and transistor the correct way around
as indicated in fig 1 . Finally insert the 4 ICs, again consult fig 1 for
polarity ICQ Inserted the Wrong way
artpund will almost certainly ba destroyed when the board IB plugged m so be
particularly careful here
Vhen construction ifl complete, plug in the board, and apply power to the
ZX Again the machine should operate as normal if not, check that the ICa
arq correctly inserted, and that there are no board shorts.
Once
the
board
la
functioning
there
are
many
tests
and
experiments
that
Bay be
performed
including
full
freo^jency
range"
audio
output
See
arti
clSB
m
Personal
Computer
World
(October
and
November
1981),
But
here
are
BOme
introductory notes!
Output Fort
Connection to the port are shown in fig 2 There are 8 separate output
channels,
and
they
may be
controlled
with
a
single
poke
statement!
POKE
25000,
X for the
ZXBQ
or
POKE
11000,X
for the 81. X may be any
integer
between
0 and
255
With
£=Q all
output
linaa
are eet to
logic
lov,
whilst
255
Bate
them
all
high To set any one channel high while leaving the remainder low, the follow-
ing valuaa should be used:
POKE VALUE (X) CHANNEL ACTIVATED
1 0
2 1
4 2
8 3
16 4
32 5
64 6
128 7
Thus
the
command
POKE
25000,
16 (or
POKE
11000,
16 on the 81)
will
set
channel
4
high, leaving
the
others
low
Setting
a
high output
on a
number
of
channels
ia
achieved
by
combining
the
data
Thus
POKEing
the
value
12
(=9+4)
will
set
channels 2 and 3 high
When
a
channel
goes
high
it may be
used
to
trigger
a
variety
of
devices.
Fig 3
shows
LED
indicator
lamps
attached
to
channels zero
and one To
light
these,
execute
POKE
25000,
3 (or
POKE
11000,
3 on the
ZX81)
Belaya
may be
controlled
from
each channel
as
shown
in the
application
notes,
and
sound
output
may be
produced
by
connecting
a
high
impendence
(eg 65
ohm) loudspeaker to the ouput plug aa In fig 4 The following programs will
produce blips on the loudspeaker
10 EB« ZX80 BLEEP 10 HEM ZXB1 BLEEP
20 FOR A = 1 TO 100 15 FAST
30
POKE
25000,1
20
Kffl
A = 1 TO 100
40
POKE
25000,0
30
POKE
11000,1
50
HBCT
A 40
POKE
11000,0
50 NEXT A
To
produce
a
higher frequencies
and
more
interesting
effects
it ia
necessary
to uee a
machine
code
subroutine,
and
complete
programs
for
this
on
both
2X60
and 81 are given in tha applications notes, and in PCW.
•
B»«_»r-iiAi%_MVIA*l
ll~»
R-IIVH
I
fc=l
I .^
17 BURNLEY ROAD
LONDON NWIO IED
Telephone OI-452 I5OO OI-45O 6597
IBS
2X80/61
Pom -
KOTES
TO
ACCOHPAHY
KIT
The following is provideds-
1 Double Bided FOB
4 IOB labelled 1-4
1
Diode
(IN9-14)
(glassy)
1 Heslstor (IK)
2
Capacitors
(lOOn?)
(round
and
flat)
2 14 Pin Dil Sockets
2 16 Pin Dil Sockets
2 20 Pin Dil Sockets
1 23 x 2 0 1" edge connector
2 16 Pin Header Plugs
1 2S2926 (green) Translator
1 HAH pack extender card (ZX81 only)
Confltraction
Begin construction as follows! Insert and Bolder in the 6 1C Sockets,
putting
in the
largest
ones
first
Next
Bolder
in the 2 3 way
edge connec-
tor, but if the board is for use with the ZXS1 do not trim short, the wires
protruding through the underside of theboard, because these will be used for
connecting
the
RAM
pack extender
card,
(this
is not
possible
on the
ZX80)
Hot*
that
the
edge connector
whould
have
a
plaatio
plug
at pin }. Be
very
careful
not to
bridge adjacent
tracks
when
soldering
this
socket.
To
reduce
the
risk
of
this
you can
leave
unsoldered
any
pins
that
don't
appeal
to
Join
up to a track on the underside of the board Insert the two capacitors and
resistors,
and
Bolder
these
Next
solder
the
through connections
at all the
remaining holes
that
have
solder
pads on the upper side of the board except
EITHER
the
three
marked
«A" if the
board
is for use
with
a
ZX81 (note
that
the
third
'A' le
somewhat
obscured
by the
edge connector)
OH the two marked B if it la for a ZX60. The through connec-
tions require a piece of wire to be passed through the board,
end carefully soldered both sides before clipping off.
At
this
point,
and
before
inserting
the ICs or the
diode
and
transistor,
plug
the
board
into
the
ZX80/81,
and
plug
the
power
plug
into
the
computer
The cursor should appear, and the ZX should work normally If it does not,
there
is a
short
circuit
eomewhere
on the
board
-
probably
between
a
pair
of
adjacent tracks The short can be traced (after unplugging the board) using
a
multimeter
on the
ohms
range,
or
other continuity
tester
(eg
battery
and
bulb)
- or you can
Bsarcb.
visually.
If it io a
solder
bridge
then
you
must
reaolder
the point, but you Day find that you can ole.ir tha short by passing & small
screwdriver
bl*-^
between
the
offending
tracks.
( \
To Next Page
Loading...
