Introduction - Computer Busses - page 10

IBM's fastest mainframe. The project was eventually cancelled as a competing project
named 'Future Systems' was consuming much of IBM's resources.
In the next year (1974), several personal computers began to appear, including the MITS-
built ( Micro Instrumentation and Telemetry Systems) computer based on Intel's new 8080
device, at the cheap price of $500. It was released as the Altair 8800 microcomputer. One of
the first prototypes for the Altair computer was lost, en-route, to New York, as it was to be
reviewed and photographed for Popular Electronics. Eventually they did receive a new ver-
sion and at a selling price of $439, it received great reviews.
At PARC, the Bravo was developed for the Xerox Alto computer and demonstrated the
first WYSIWYG (What You See Is What You Get) program for a personal computer. The
Alto computer was then released onto the market. The following year Xerox demonstrated
the Gypsy word-processing system, which was fully WYSIWYG. At Motorola, Chuck Ped-
dle and Charlie Melear developed the 6800 microprocessor, which was never really success-
ful in the personal computer market, but was used in many industrial and automotive applica-
tions.
While many of the processors at the time ran at 1 MHz or, at the most, 5 MHz, RCA re-
leased the RISC-based 1802 processor, which ran at 6.4 MHz. It was used on a variety of
systems, from video games to NASA space probes.
Up to 1974, most programming languages had been produced either as a teaching lan-
guage, such as Pascal or BASIC, or had been developed in the early days of computers, such
as FORTRAN and COBOL. No software language had been developed that would properly
interface with the operating system, and used both high-level commands, and supported low-
level commands (such as AND, OR and NOT bitwise operations). To overcome these prob-
lems, Brian Kernighan and Dennis Ritchie developed the C programming language. Its main
advantage was that it was supported in the Unix operating system. C has since led a charmed
existence by software developers for many proven (and unproven) reasons, and quickly took
off in a way that Pascal had failed to do. Its main advantages were stated as: being both a
high- and a low-level language, it produced small and efficient code, and that it was portable
on different systems. The main advantage was probably that it was a standard software lan-
guage that was supported on most operating systems, and the ANSI C standard helped its
adoption. For this, a program written on one computer system would compile on another
system, as long as both compilers conformed to a given standard (typically ANSI C). Pascal
always struggled because many compiler developments used non-standard additions to the
basic language, and thus Pascal programs were difficult to port from one system to another.
FORTRAN never really had this problem, as it only had a few standards, mainly FORTRAN
57 and FORTRAN 77. BASIC also had few problems because of the lack of additional
facilities. Most BASIC programs did not port well from one system to another, as they
tended to use different methods to access the hardware. Typically, BASIC accessed the
hardware directly, whereas C has tended to use the operating system to access the hardware.
The non-direct method had many advantages over direct access. Non-direct accesses allow
for multi-access to hardware, hardware independence, time-sharing, smoother running
programs and better error control. C moved from the Unix operating system down to the
PCs, as they become more advanced. It normally requires a relatively large amount of
storage space (for all of its standardised libraries), whereas BASIC requires very little
storage space. In 1975, Micro-soft (as it was known before the hyphen was dropped) realized the poten-

tial of BASIC for the newly developed 8-bit computers and use it to produce the first pro-
gramming language for the PC. Their first product was BASIC for the Altair, and licensed it
to MITS, their first customer. The MITS, Altair 8800 was a truly innovative system and sold
for $375 and has 1 KB memory (Figure 1.5). Soon Microsoft BASIC 2.0, for the Altair 8800,