Marshall McLuhan's statement that "the medium is the message" captured the reality of communications until the digital age. Communicating digitally involves the transfer of information as streams of bits. No longer does matter need to be moved. In the case of data representing continuous waveforms, the communication is complete when the recipient possesses a digital representation of the original signal with a given fidelity criterion. This allows one to embed watermarks to deliver hidden information. In the case of discrete data files, the communication is complete when the recipient possesses the identical stream of bits delivered by the source: at that moment there are two, identical, streams of bits. It is impossible to characterize one as the original and the other as the copy. Consequently, one loses control of digital information after transmitting it to another. The recipient is free to use their original as they see fit. The ubiquitous PC and Internet provide the means easily and inexpensively to copy and distribute data files to anyone wishing to do so. We introduce a framework for persistent access control over digital data. That is, data remain under the control of their originator, even after another has received them. This requires the use of multiple levels of encryption, transmission of ciphering keys through licenses associated with the data, and of trusted hardware and trusted software (access control mechanism) to ensure that the originator's restrictions are not circumvented. We show how a PC or consumer electronics appliance can accommodate the required system-while remaining compatible with previously produced data. This material is the subject of a pending U.S. Patent Application (allowed) and foreign applications.

Three "technologies" are driving the growing use of computers. First, the underlying component technology simultaneously is becoming less expensive and more capable. Computation rate and reliability are increasing, while requirements for space and power are decreasing. Second, the communications infrastructure is undergoing a similar increase in capability and decrease in cost. Last, breakthroughs in computer science and mathematics, coupled with increases in raw computing speed, are providing solutions to problems previously thought to be intractable.

Presents a review of this classic paper. The body of the paper is divided into five sections: general circuit design considerations; types of computing circuits; flip-flop and counter design; units of the ENIAC; and analysis of typical circuits. Each section is described in this review.

Abstract A common myth surrounding virtual memory systems is that they eliminate completely the need for programmers and analysts to deal with conservation, allocation, and management of addressable memory. This paper shows that paying appropriate attention to these factors can have even greater impact on virtual memory system performance than on real memory system performance. Guidelines for effectively using virtual memory are presented.

This correspondence indicates a weakness in forming the criteria used to decide when random testing is practical. The use of average fan-in based on total gate count is an oversimplification and results in too low a threshold for use of random testing in lieu of a complete test of 2N patterns. A modification is given to avoid this difficulty.

Abstract A common myth surrounding multiprogramming is that it it a necessary mode of operation to deal with the high levels of I/O activity found on most computers. This paper shows that the high level of I/O activity is to a great extent a direct result of multiprogramming. Monoprogramming is proposed as a method of achieving high performance which yields advantages in turnaround time, efficiency and equipment configuration.

This paper describes the implementation of a machine independent compiler designed to produce optimised source code for a higher level language. The advantages of optimising at the source rather than the machine code level are discussed. Optimisation techniques are set out in detail, paying particular attention to analysis of program structure and optimisation in the presence of flow.