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This programme examines the theory and practice of four sub-routine facilities provided by OPUS 2.
Metadata describing this Open University video programme
Module code and title: TM221, The digital computer
Item code: TM221; 06
First transmission date: 1975
Published: 1975
Rights Statement:
Restrictions on use:
Duration: 00:24:12
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Producer: Ted Smith
Contributors: Richard Maddison; Ray Morgan
Publisher: BBC Open University
Keyword(s): Assembler; Command interpreter; Digital computing; Loader; OPUS 2; Program editing
Footage description: Ray Morgan introduces the similuted minicomputer OPUS 2. He explains the advantages OPUS 2 has over OPUS 1 . partucularly in the inclusion of an Assembler. Using graphics he compares a simple program in numerical machine code, suitable for OPUS 1, and in mnemonic form for OPUS 2. He also explains the use of origin and finish directives. At the OPUS 2 terminal, Morgan describes its facilities. He then outlines the other systems programs of OPUS 2 in addition to the Assembler - the Editor, the Loader and the Command Interpreter - and explains their advantages. He states what this program hopes to achieve. With the help of a diagram, Richard Maddison provides a conceptual background to these systems programs. He explains what the programmer's job involves and how systems can make it easier. He employs a graphics board to explain the composition of the whole system used in OPUS 2. Morgan deals with the practical aspects of the system as a programmer. He describes the input and output devices of the computer terminal. He uses an animated diagram to represent the whole system used in OPUS 2, and shows the storage of individual program systems in the main and backing stores. He indicates the relation of these to the peripherals. Morgan runs a program on OPUS 2, using the terminal's keyboard and paper tape puncher. The input of the program to the Assembler is seen on the terminal's line-printer. This target program appears in the form of paper tape. Maddison uses a graphics board to demonstrate what this actual use of the Assembler means in terms of computer hardware. He also shows what will happen next. Morgan now runs the program on paper tape to the Loader via the terminal's paper tape reader. This completed, he gives the execute instruction and the program is run. Maddison shows the link between the STOP instruction and the Loader on the graphics board. He then describes alternative commands available at this stage and which aren't available on OPUS 1 One particular example which he stresses is the dumping of the contents of store locations to the line printer. Morgan then uses this facility, enabling him to check that the program has worked successfully. Maddison briefly explains the nature and use of files kept on paper tape and on disc. Advantages of disc explained. He describes the use of the Editor when altering a program. Morgan runs the whole program cycle at the terminal, using disc files, instead of paper tape. The results are seen on the lineprinter, with Morgan explaining their significance throughout, Morgan concludes the program with some advice for students.
Master spool number: 6HT/71665
Production number: 00525_5165
Videofinder number: 1464
Available to public: no