Interface

Florian Cramer and Matthew Fuller


It seems as if the term "interface" is borrowed from chemistry where
it means "a surface forming a common boundary of two bodies, spaces,
phases". {1} In computing, interfaces link software and hardware in
relation to each other and to their human users or other sources of
data. A typology of interfaces thus reads:

(a) hardware that connects users to hardware; typically input/output
devices such as keyboards or sensors, and feedback devices such as
screens or loudspeakers

(b) hardware that connects hardware to hardware; such as network
interconnection points and bus systems.

(c) software, or hardware-embedded logic, that connects hardware to
software; the instruction set of a processor or device drivers for example.

(d) specifications and protocols that determine relations between software
and software; i.e. application programming interfaces (APIs)

(e) symbolic handles which, in conjunction with (a), make software
accessible to users; i.e. "user interfaces", often mistaken in media
studies for "interface" as a whole.  In a software studies context,
only the three (c), (d) and (e) are of particular relevance.

Regarding (c), software typically functions as an interface to hardware.
Computer programs can be seen as tactical constraints of the total
possible uses of hardware. They constrain, for example, the combination
of a CPU, RAM, hard disk, mainboard, video card, mouse, keyboard and
screen with its abundant possible system states to the function of
a word processor, a calculator, a video editor etc.. In other words,
they interface to the universal machine by behaving as a specialized
machine, breaking the former down to a subset of itself. This operation
is linguistic because it reformulates the totality of available machine
instructions into a new control language. This language acts as an
"abstraction layer". It is either a subset of the total available
instructions when it is Turing incomplete, or a redressing of them with
different symbolic handles when it is Turing complete.

"User interface" and "programming interface" have not always differed.
They used to be identical in many operating systems up to 8-bit home
computers in the 1980s that booted into a BASIC programming language
prompt, or MIT's Lisp machines which had a Lisp programming environment
as their user interface. Character-based shells such as the DOS and
Unix shells are used both as programming and user interfaces. The same
is true, to a lesser degree, for graphical user interfaces when they are
scriptable.  But even if they are not scriptable, they still effectively
act as specialized symbolic computer control languages. The distinction
between a "user interface", an "Application Program Interface" (API)
and a computer control language is purely arbitrary.  That more complex
interfaces to computer functions tend to be called "programming languages"
and less complex, more specialized ones are known as "user interfaces" is
simply a nomenclature arising out of convention.  Since the user interface
to a computer program is always symbolic, and involves syntactical
and symbolic mappings for operations, it always boils down to being a
formal language.  To the extent that they are understood symbolically,
everything that can be said about software interfaces falls under the
entry on language.  

Interfaces, as with the word's etymological roots in chemistry and like
language, describe the point of conjuncture between different bodies,
hardware, software, users, and what they connect to or are part of.
Interfaces describe, hide and condition the asymmetry between the
elements conjoined. The asymmetry of the powers of these bodies is what
draws the elements together, unless they are a savant a human user
cannot calculate Pi to the 100th place, or generate a model world in
which the dimensions and trajectory of every element in it are mapped,
within the small amount of time that a computer does so. In this sense
the term interface emphasizes representation, or more closely, re-
articulation at another scalar layer, while the term language in a
computer context emphasizes control. The dense condensations of
computational power which computers embody and which are differently
articulated by individual pieces of software are of intense fascination
and productivity, and at the same time, radically alien to different
human experiences of the world. It is this alienness that allows
software, particularly at moments when one is attempting to understand
its workings, or to program it, that engenders the delicious moments of
feedback between the styles of perception and ordering, logic and
calculation, between the user and the computer to be so seductive and
compelling. At the same time, such a rich engagement with an interface
tends to wear out once users realize the limitations of the programmed
system.  Equally, as when software is used to monitor, queue and
structure the flow of work, the compulsion can often be of a different
kind. The asymmetric powers conjoined by means of human-machine
interfaces, also find themselves arranged in other relations which
themselves articulate, filter and organise the activities modelled and
modulated by the interface.

This asymmetry, while it is fundamental to the difference between human
and machine operations, can further materialize in different levels of
machine control granted to the user.  While any user interface, including
every programming language, mediates machine functions, the mediation
can be deliberately (Turing-)incomplete or (Turing-)complete. But even
the latter usage and programming interface, Unix shells or the turtle of
the Logo programming language for example, still impose, and enhance -
like any language or instrument - particular workflows, thought modes,
and modes of interaction upon or in combination with human users.

Asymmetry of powers is also mapped and sieved through interfaces in other
ways. A search engine operates as an interface of many layers, ostensibly
that between the user and the data they are seeking. But crucially,
it also instantiates an interface whereby the database can read the
user, by means of records of patterns of search terms and choices. And
asymmetry is not simply a means of recognising the associations made
between computers and humans. APIs as well as protocols that operate as
interfaces between computers linked over a network equally establish
descriptions of operations that are allowed and assigned a priority
or blocked. APIs are increasingly important with the development of
networks that rely on data and software working without being constrained
by their hardware platform, and the formulation of the algorithms that
govern their operation has become of particular interest.

Within the paradigm of "user- friendliness", that which is most easily
recognisable and visible, software has been traditionally understood
to place the user as its subject, and the computational patterns and
elements initiated, used and manipulated by the user as the corresponding
grammatical objects. As software is increasingly diffused through urban,
social and institutional contexts, the design of interfaces and even the
basic level of awareness as to what does or does not constitute part of
an interface or that triggers a computational event becomes increasingly
important. Learning to recognise a human functioning as an interface to
a spreadsheet, or, as in much of generic electronic art, being able to
read the sensors in a constructed space are increasingly useful skills
as interfaces not only spread out from the screen and the keyboard,
but are also designed to dissimulate their function as interfaces.

Within (e) the user interface articulates asymmetry via different
means: by the use of text; visual- spatial structuring devices such
as a window and its subcomponents, timeline or button; sounds, such as
system event sounds; animated representations of running data-processes
such as a "loading" bar, "throbbers" (used in browsers), spinning
cursors; widgets; menus, which describe available functions; and other
elements. Because such interface elements provide a mode of access to data
and data structures, the ordering and occurrence of such elements are
usually describable by and at a lower level designed using formalisms,
context-free grammars which attempt to describe a metasyntax comprising
every possible use of the computer or within a language or application. If
the universal machine describes every possible rational computation,
such systems set out the syntax for all possible interactions within the
domain they describe. Whilst the syntax of an interaction is logically
describable, no such constraint is necessary for visual or audio elements
of interface within (e).  Such interfaces, and especially the skinning
systems that provide users with the opportunity to "personalise" the
visual appearance of interface elements in applications or operating
systems, conjoin, even if only at the representational level, formal
grammars with assemblages of visual codes drawn from domains as diverse as
heavy metal and manga graphics. Low-level formalisms articulated through
the representational matrices of high-trash generic conventions provide
a refreshing break from the pretensions of computing to objectivity.
The meshing of poetic and formal language in the area of writing known
as codeworks explores the rich experimental and speculative potential
of alphanumerical computer control languages. Other net and software
artists have demonstrated how audiovisual computer control languages
(user interfaces) can be a playground for subjective, ironical and
epistemological disruptions, experiments and critique. These interventions
become all the more important the more the deliberate separation between
"user" and "programming" interfaces and languages is being mainstreamed.

Footnotes


{1} According to Webster's Ninth Collegiate Dictionary which dates the
term to 1882