This thesis describes an experiment in developing a true high-level microprogramming language for the Burroughs B1700 series of computers. Available languages for machine description both at a behavioural level and at a microprogramming level are compared and the conclusion drawn that none were suitable for our purpose and that it was necessary to develop a new language which we call SUILVEN. SUILVEN is a true high-level language with no machine-dependent features. It permits the exact specification of the size of abstract machine data areas (via the BITS declaration) and allows the user to associate structure with these data areas (via the TEMPLATE declaration), SUILVEN only permits the use of structured control statements (if-then-else, while-do etc.) - the go to statement is not a feature of the language. SUILVEN is compiled into microcode for the B1700 range of machines. The compiler is written in SNOBOL4 and uses a top-down recursive descent analysis technique, using abstract machines for PASCAL and the locally developed SASL, SUILVEN was compared with other high and low level languages. The conclusions drawn from this comparison were as follows: - (i) SUILVEN was perfectly adequate for describing simple S-machines (ii) SUILVEN lacked certain features for describing higher-level machines (iii) The needs of a machine description language and a microprogram implementation language are different and that it is unrealistic to attempt to combine these in a single language.