Sinclair ZX81 Assembly Instructions

R10 470 Q
R11 470 Q
R12 470 fi
R13 470 £2
R14 470 £2
R15 220K Red Red Yellow
R16 IK Brown Black Red
R17 1K
R18 1K
R19 1K
R20 1K
R21 1K
R22 K
R<
" IK
R24 IK
R25 1K
R26 1K
R27 1K
R28 680Q Blue Grey Brown
R29 1M Brown Black Green Fourth band may be yellow
R30 Not used
R31 Not used
R32 Not used
R33 4K7 Yellow Purple Red
R34 220Q Red Red Brown
(b) Resistor Packs
No. Value Markings Comments
RP1 8 x 10K 10KQ 9 leads '
RP2 Not used
RP3 5 x 10K 10KQ 6 leads
(c) Capacitors
No. Values Markings Comments
C1 47pF 47 Ceramic disc
C2 47nF 473 Z
C3 22uF 22 H Electrolytic 16V mm
C4 47nF 473 Z Ceramic disc
C5 1uF 1[i Electrolytic 5V min.
C6 100pF 100, 101, nlO Ceramic disc
C7 47pF 47
C8 47nF 473 Z
C9 47nF 473 Z
CIO lOnF lOn, 103
Cll 47nF 473 Z
C12 47pF 47
(d) Semiconductors
No. Type Comment
IC1 Sinclair
Logic 1C 40 pins 158 printed underside
!C2 2364 24 pins
IC3 Z80A or D780C-1 40 pins
IC4 MK4118 24 pins
or
IC4a uPD2114LC
or as IC4b 18 pins
6

Sinclair ZX81 Specifications

General

Processor	Zilog Z80A
Processor Speed	3.25 MHz
ROM	8 KB
Input	Membrane keyboard
Storage	Cassette tape
Power Supply	9V DC
Dimensions	167 mm x 40 mm x 175 mm
Release Year	1981
Manufacturer	Sinclair Research
Weight	350 g
Operating System	Sinclair BASIC
RAM	1 KB
Ports	TV out, expansion port
Display	Television (RF modulator output)