ULA:

/CAS 1 40 GND One of the +5V is decoupled through a RC-low-pass.
/WR 2 39 Q U,V are the color-difference signals.
/RD 3 38 /MREQ /Y is the inverted video including sync.
/WE 4 37 A15 D are the data-lines, decoupled from the CPU by resistors.
A0 5 36 A14
A1 6 35 /RAS T are the data-lines to the keyboard (address-lines through diodes)
A2 7 34 /ROM CS
A3 8 33 /IO-ULA SOUND is the analog-I/O-line for beep, save and load.
A4 9 32 CLOCK CLK is the clock-source to the CPU including the inhibited T-states.
A5 10 31 D7
A6 11 30 D6 IO-ULA is (A0(CPU) OR /IORQ) for the I/O-port 0xfe
/INT 12 29 D5 Q is the 14MHz-crystal, other side grounded through a capacitor.
+5V 13 28 SOUND
+5V 14 27 D4
U 15 26 T4
V 16 25 D3
/Y 17 24 T3
D0 18 23 T2
T0 19 22 D2
T1 20 21 D1

 

AY-3-8912 Sound Chip:

SOUND C 1 28 D0 Vcc is +5V.
PORT 2 27 D1 SOUND A, B and C can be tied together.
Vcc 3 26 D2 CLOCK can be some MHz.
SOUND B 4 25 D3
SOUND A 5 24 D4
GND 6 23 D5
PORT 7 22 D6
PORT 8 21 D7
PORT 9 20 BC1
PORT 10 19 BC2
PORT 11 18 BDIR
PORT 12 17 A8
PORT 13 16 RESET
CLOCK 14 15 CLOCK| note that the AY-3-8912 used in the Timex TS2068 runs at 1.76475Mhz |

Keyboard Layout:

OUTER SIDE A 15 14 8 13 12 9 10 11 INNER SIDE
D
0 BR EN CS P 0 A Q 1
1 SS L Z O 9 S W 2
2 M K X I 8 D E 3
3 N J C U 7 F R 4
4 B H V Y 6 G T 5
INNER SIDE

[BR] BREAK [EN] ENTER [CS] CAPS SHIFT [SS] SYMBOL SHIFT| in reality, the matrix connections are in one row on the top side of the membrane |

128K Composite Video Output:
Pin 1 is composite PAL, 2 is GND. There's no audio on any pin of the RGB connector.

The picture is a bit dull unless your TV's video input is High Z (high impedance) However, that's quite unlikely. Normally the impedance of the video input is around 75 Ohms. To alleviate this problem, short the 68 Ohms resistor inside the Speccy that's in series with pin 1 (follow the track on the PCB). Or you can hook it directly to the input of the RF modulator.

The audio can be taken from the MIC socket but a better balance between 48K and 128K sound is obtained directly from pin 5 of IC38.

128K RGB Video:

128K ZX Spectrum:

RGB Pin Signal Level
-------------------------------------------------
--7-- --6-- 1 Composite PAL 75 Ohms, 1.2 Volts pk-pk
| 2 0 Volts DC
3-- 8 --1 3 Bright output TTL
-- | -- 4 Composite sync TTL
/ \ 5 Vertical sync TTL
5 | 4 6 Green TTL
/ 2 \ 7 Red TTL
| 8 Blue TTL

ZX Spectrum +2A / +3:
RGB Pin Signal Level
-------------------------------------------------
--7-- --6-- 1 +12V
| 2 GND 0V
3-- 8 --1 3 Audio Out
-- | -- 4 /Composite Sync TTL
/ \ 5 +12V
5 | 4 6 Green Analogue 1.67V p-p
/ 2 \ 7 Red Analogue 1.67V p-p
| 8 Blue Analogue 1.67V p-p

 

Power Supplies:
Information about hardware and peripherals with entries elsewhere in this FAQ can be found on the appropriate pages.

Machine Voltage Amperage Centre Polarity
-------------------------------------------------------
ZX81 9V DC 500 mA +ve
Timex 1000/1500 9V DC 500 mA +ve
TC 2048 9V DC 800 mA -ve
TC 2068 9V DC 1.0 A -ve
TS 2068 15V DC 1.0 A -ve
Z88 6.5V DC 500 mA +ve
Flat-screen TV 5.9V DC 100 mA -ve

 

ZX Interface I RS-232:

The RS-232 socket provided on the ZX Interface I has the following configuration:

Not Connected.
TX Data - Input.
RX Data - Output.
DTR - Input. This should be high when ready.
CTS - Output. This should be high when ready.
Not Connected.
Ground. Pull down.
Not Connected.
+9v - Pull up.
/----------------------\
\ 5 o o o o o 1/
\ 9 o o o o 6 /
\------------------/

An RS-232 cable will be required to connect to other peripherals. This must be wired as follows:
(Pin 2) - TX Data.
(Pin 3) - RX Data.
(Pin 5) - CTS.
(Pin 6) +9V - Normally DSR.
(Pin 7) - Ground.
(Pin 20) - DTR.