In jazzimprovisation, outside playing, describes an approach where one plays over a scale, mode or chord that is harmonically distant from the given chord. There are several common techniques to playing outside, that include side-stepping or side-slipping, superimposition of Coltrane changes, and polytonality.
The term side-slipping or side-stepping has been used to describe several similar yet distinct methods of playing outside. In one version, one plays only the five "'wrong'" non-scalenotes for the given chord and none of the seven scale or three to four chord tones, given that there are twelve notes in the equal tempered scale and heptatonic scales are generally used. Another technique described as sideslipping is the addition of distant ii-V relationships, such as a half-step above the original ii-V. This increases chromatic tension as it first moves away and then towards the tonic. Lastly, side-slipping can be described as playing in a scale a half-step above or below a given chord, before resolving, creating tension and release.
The Phoenix system was an IBM 370/165. It was made available for test purposes to 20 selected users, via consoles in the public console room, in February 1973. The following month, the Computing Service petitioned the Computer Board for an extra mebibyte of store, to double the amount of storage that the machine had. The petition was accepted and the extra store was delivered in September 1973.
The IBM-supplied Telecommunications Access Method (TCAM) and communications controller were replaced in 1975 by a system, called Parrot, that was created locally by the staff of the Computer Laboratory, comprising their own software and a PDP-11 complex. Their goal in doing so was to provide a better user interface than was available with a standard IBM system, alongside greater flexibility, reliability, and efficiency. They wanted to support 300 terminals. The initial system, supplied in 1972, comprised the PDP-11 emulating an IBM 2703 transmission control unit, which TCAM communicated with just as though it were a 2703. The PDP-11 was used instead of a bank of 2703s because for a projected 300 terminals a bank of 2703s was not scalable, too expensive, and inadequate for the Computing Service's needs, since it required paper tape readers and card punches as well. Even this solution proved to be unsatisfactory, and in 1975 TCAM was replaced by Parrot, with 200 terminals connected to the PDP-11, of which 80 could be simultaneously active. For full technical details of Parrot, see the technical report by Hazel and Stoneley.