BCL Molecular

The BCL Molecular 18 was a range of 18-bit computers designed and manufactured in the UK from 1970 until the late 1980s.
The machines were originally manufactured by Systemation Limited and serviced by Business Mechanisation Limited. The two companies merged in 1968 to form Business Computers Limited - a public limited company. Business Computers Ltd subsequently went into receivership in 1974.
It was purchased from the receiver by Computer World Trade, maintenance of existing machines was by a subsidiary of CWT called CFM, manufacturing was passed to ABS Computer in the old BCL building and sales rights were sold to a team from the old Singer Computers by 1976 trading as Business Computers (Systems) Ltd selling the Molecular.
BC(S) Ltd subsequently went public in 1981 to form Business Computers (Systems) Plc. Servicing and manufacturing was gradually taken over by Systemation Services/ Systemation Developments Ltd. BC(S)Plc was eventually taken over by Electronic Data Processing (EDP). Amongst its users and service engineers it was affectionately known as the Molly.

Operating system known as LOS developed by Joe Templeman in Leicester office of Systemation. Programming was done in octal notation machine code in longhand using coding sheets. The 17 bit word allowed the limited storage of 3 bytes per word using "Metacode"

Front-loading disk drive
Optional paper tape reader D400 front-loading cartridge 875 kbit D800 1.75 Mbit

Water-cooled cabinets with remote chiller unit initially, later normal fan cooling.

Programming still done in octal notation machine code in longhand using coding sheets.

Hardware re-design by Systemation Developments K. A. Howlett (Keith Alec b1943 son of W A Howlett)with assistance in the final test stages by G. Boote. Cabinet design by Business Computers Systems Ltd. Hardware designed and manufactured by Systemation Developments for Business computers Systems.

Later Bank switching memory introduced (32K 18 bit words base memory plus up to 8 X 32K banks).

First sold with CDC Hawk 9427H drives later CDC Lark 2 disk drives. Memory and new RS232 4 port I/O card (Quad I/O) by K. A. Howlett, Lark 2 disc controller by J. Adams. Up to four CDC Lark or Amcodyne drives per controller, max 2 controllers.

Note that neither SADIE nor SUSIE shared any technology with the Molecular series.

...
Wikipedia