ELLA is a

hardware description language In computer engineering, a hardware description language (HDL) is a specialized computer language used to describe the structure and behavior of electronic circuits, and most commonly, digital logic circuits. A hardware description language e ...

and support toolset, developed in the United Kingdom by the Royal Signals and Radar Establishment (RSRE) during the 1980s and 1990s, which also developed the

compiler In computing, a compiler is a computer program that translates computer code written in one programming language (the ''source'' language) into another language (the ''target'' language). The name "compiler" is primarily used for programs that ...

for the

programming language A programming language is a system of notation for writing computer programs. Most programming languages are text-based formal languages, but they may also be graphical. They are a kind of computer language. The description of a programming l ...

, ALGOL 68RS, used to write ELLA. ELLA has tools to perform: * Design transformation *

Symbolic simulation In computer science, a simulation is a computation of the execution of some appropriately modelled state-transition system. Typically this process models the complete state of the system at individual points in a discrete linear time frame, comp ...

s *

Formal verification In the context of hardware and software systems, formal verification is the act of proving or disproving the correctness of intended algorithms underlying a system with respect to a certain formal specification or property, using formal met ...

ELLA is a winner of the 1989 Queen's Award for Technological Achievement.

Sample

Sample originally from ftp://ftp.dra.hmg.gb/pub/ella, public release. Code for matrix multiplication hardware design verification:

MAC ZIP = ( NT nYPE t: vector1 vector2) ->  2]t:
   NT k = 1..nvector1  vector2 .
     
MAC TRANSPOSE = ( NT nINT m]TYPE t: matrix) ->  n]t:
   NT i = 1..m NT j = 1..nmatrix i].

MAC INNER_PRODUCT
                 = ( NT n2]t: vector) -> s:
  IF n = 1 THEN *vector   ELSE *vector + INNER_PRODUCT  vector ..n  FI.

MAC MATRIX_MULT  =
( NT nINT m]t: matrix1,  INT p]t: matrix2) ->  p]s:
BEGIN
  LET transposed_matrix2 = TRANSPOSE matrix2.
OUTPUT  NT i = 1..nINT j = 1..p]
       INNER_PRODUCTZIP(matrix1 transposed_matrix2 
END.

TYPE element = NEW elt/(1..20),
     product = NEW prd/(1..1200).

FN PLUS = (product: integer1 integer2) -> product:
  ARITH integer1 + integer2.

FN MULT = (element: integer1 integer2) -> product:
  ARITH integer1 * integer2.

FN MULT_234 = ( 3]element:matrix1,  4]element:matrix2) ->
              4]product:  
  MATRIX_MULT(matrix1, matrix2).

FN TEST = () ->  4]product:
( LET m1 = ((elt/2, elt/1, elt/1),
            (elt/3, elt/6, elt/9)), 
      m2 = ((elt/6, elt/1, elt/3, elt/4), 
            (elt/9, elt/2, elt/8, elt/3),
            (elt/6, elt/4, elt/1, elt/2)).
  OUTPUT
    MULT_234 (m1, m2)
).

COM test: just displaysignal MOC

References

* * *

External links

ELLA source code
including the ALGOL 68RS translator Hardware description languages History of computing in the United Kingdom {{Prog-lang-stub