Computing History Timeline
ALGOL Programming Language
ALGOL (algorithmic language in short) was an interpretive computing programming language that was developed in the 1950’s which influenced many other programming languages like CPL, Pascal and Scheme.
There were 3 main branches of the ALGOL programming family:
ALGOL 58- originally known as IAF (international algorithmic language)
ALGOL 60- revised in 1963
ALGOL 68- revised in 1973
ALGOL was first created by a group of European and American computer scientists in a meeting in 1958 at ETH Zurich.
ALGOL 60 as officially defined had no I/O facilities; implementations defined their own in ways that were rarely compatible with each other. In contrast, ALGOL 68 offered an extensive library of transput (ALGOL 68 parlance for Input/output) facilities. ALGOL 60 only had 2 main parameters, called-by-reference and called-by-name. by having these, it set many limits to what the language could do. For example it would be impossible for ALGOL 60 to develop a procedure of swapping the values of 2 parameters.
Code sample (ALGOL 60)
(The way the bold text has to be written depends on the implementation, e.g. 'INTEGER' (including the quotation marks) for integer.)
procedure Absmax(a) Size:(n, m) Result:(y) Subscripts:(i, k);
value n, m; array a; integer n, m, i, k; real y;
comment The absolute greatest element of the matrix a, of size n by m
is transferred to y, and the subscripts of this element to i and k;
begin integer p, q;
y := 0; i := k := 1;
for p:=1 step 1 until n do
for q:=1 step 1 until m do
if abs(a[p, q]) > y then
begin y := abs(a[p, q]);
i := p; k := q
end
end Absmax
ALGOL 68 on the other hand was defined as using a two-level grammar formalism. Using a context-free grammar to generate an infinite set of productions that would recognize a particular ALGOL 68 program.
ALGOL 68
Main article: ALGOL 68
In the language of the "Algol 68 Report", Input/output facilities were collectively called the "Transput".
ALGOL 68 code was published reserved words were typically lowercase, but bolded or underlined.
begin
print(("Hello, world!",newline))
end
OR using a specific transput channel:
begin
putf((stand out,$gl$,"Hello, world!"))
end
For ease of programming on the 7-bit computers of the time there were "official" methods to "BOLD" reserved words, for example, by using uppercase:
BEGIN
print(("Hello, world!",newline))
END
Programmers were sometimes required to totally "THINK IN UPPERCASE" on computers that only had 6-bit characters, eg the CDC "super computers". In this case the above code would be written:
'BEGIN'
PRINT(("HELLO, WORLD!",NEWLINE))
'END'
The "Algol 68 Report" was translated into Russian, German, French and Bulgarian, and allowed programming in languages with larger character sets, eg Cyrillic alphabet. eg the Russian BESM-4.
BEGIN
print(("Здравствуй, мир!",newline))
END
by Brendan Wu
