SEQ - a self-contained sequential programmer for children to control LEGO robots

SEQ programming

SEQ pack

SEQ contents

Inspired by Seymour Papert's Turtle, Logo, LEGO Control Lab, Big Track, & control technology, designed & prototyped by Paul Spurgeon in 1987, SEQ led to the formation of ProCom, a one-man company based at home in Tavistock. Hand-assembled SEQ controllers were accompanied by a pack of materials including a SEQ Teachers Guide and SEQ Manual. Production started in 1988 and approximately 700 units were sold, mostly to UK schools & LEAs. The demise of LEGO 4.5 volt motors, and release of the new LEGO Mindstorms Robotics Invention System RCX reduced demand: production ceased in 1994.

SEQ trials at CITE

SEQ drawing with a LEGO turtle

SEQ programming trials

SEQ circuit diagram

SEQ main PCB layout

SEQ keyboard matrix

SEQ finite state machine

SEQ socket & keyboard PCB layout

Hardware is based around an Intel 8039 CPU with 2716 ROM, a pair of L293 ICs driving outputs, and a LM324 for inputs. The keyboard is scanned using a 6x4 matrix, and drives a simple software state machine. Design challenges included construction of low-cost sockets for LEGO plugs, and a reliable membrane keyboard. Two double-sided PCBs are used. Software is written in 8048 assembler. Each SEQ controller has a unique serial number embedded in ROM.

Protoype SEQ

SEQ PCBs

SEQ main PCB

SEQ IO PCB

Assembled SEQ without case

Prototype had sockets along each side of the case. Production SEQs are mounted in a case with small bolts at each corner underneath the membrane keyboard.