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stream I/O

summary

    This subchapter looks at stream input and output (I/)) methods. The goal is to provide enough information to create useful programs without going into all of the details of I/O

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stub section

    This subchapter is a stub section. It will be filled in with instructional material later. For now it serves the purpose of a place holder for the order of instruction.

    Professors are invited to give feedback on both the proposed contents and the propsed order of this text book. Send commentary to Milo, PO Box 1361, Tustin, California, 92781, USA.

stream I/O

    This subchapter looks at stream input and output (I/)) methods. The goal is to provide enough information to create useful programs without going into all of the details of I/O

Ada

assembly language instructions

    Input/Output (I/O) instructions are used to input data from peripherals, output data to peripherals, or read/write input/output controls. Early computers used special hardware to handle I/O devices. The trend in modern computers is to map I/O devices in memory, allowing the direct use of any instruction that operates on memory for handling I/O.

• IN Input; MIX; initiate transfer of information from the input device specified into consecutive locations starting with M, block size implied by unit
• OUT Output; MIX; initiate transfer of information from consecutive locations starting with M to the output device specified, block size implied by unit
• IOC Input-Output Control; MIX; initiate I/O control operation to be performed by designated device
• JRED Jump Ready; MIX; Jump if specified unit is ready (completed previous IN, OUT, or IOC operation); if jump occurs, J-register loaded with the address of the instruction which would have been next if the jump had not been taken
• JBUS Jump Busy; MIX; Jump if specified unit is not ready (not yet completed previous IN, OUT, or IOC operation); if jump occurs, J-register loaded with the address of the instruction which would have been next if the jump had not been taken

MIX devices

    Information on the devices for the hypothetical MIX processor’s input/output instructions.

unit number	peripheral	block size	control
t	Tape unit no. i (0 i 7)	100 words	M=0, tape rewound; M < 0, skip back M records; M > 0, skip forward M records
d	Disk or drum unit no. d (8 d 15)	100 words	position device according to X-register (extension)
16	Card reader	16 words
17	Card punch	16 words
18	Printer	24 words	IOC 0(18) skips printer to top of following page
19	Typewriter and paper tape	14 words	paper tape reader: rewind tape

See also Input/Output Instructions in Assembly Language

chapter contents

• stream input
• stream output

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