the high three bits of T and on the Mark Stack FlipFlop (MSFF), as shown in B5x00 Relative Addressing. Language support The B5000 was designed to exclusively support high-level languages. This was at a time when such languages were just coming to prominence with FORTRAN and then COBOL. FORTRAN and COBOL were considered weaker languages by some, when it comes to modern software techniques, so a newer, mostly untried language was adopted, ALGOL-60. The ALGOL dialect chosen for the B5000 was Elliott ALGOL, first designed and implemented by C. A. R. Hoare on an Elliott 503. This was a practical extension of ALGOL with I/O instructions (which ALGOL had ignored) and powerful string processing instructions. Hoare's famous Turing Award lecture was on this subject. Thus the B5000 was based on a very powerful language. Donald Knuth had previously implemented ALGOL 58 on an earlier Burroughs machine during the three months of his summer break, and he was peripherally involved in the B5000 design as a consultant. Many wrote ALGOL off, mistakenly believing that high-level languages could not have the same power as assembler, and thus not realizing ALGOL's potential as a systems programming language. The Burroughs ALGOL compiler was very fast — this impressed the Dutch scientist Edsger Dijkstra when he submitted a program to be compiled at the B5000 Pasadena plant. His deck of cards was compiled almost immediately and he immediately wanted several machines for his university, Eindhoven University of Technology in the Netherlands. The compiler was fast for several reasons, but the primary reason was that it was a one-pass compiler. Early computers did not have enough memory to store the source code, so compilers (and even assemblers) usually needed to read the source code more than once. The Burroughs ALGOL syntax, unlike the official language, requires that each variable (or other object) be declared before it is used, so it is feasible to write an ALGOL compiler that reads the data only once. This concept has profound theoretical implications, but it also permits very fast compiling. Burroughs large systems could compile as fast as they could read the source code from the punched cards, and they had the fastest card readers in the industry. The powerful Burroughs COBOL compiler was also a one-pass compiler and equally fast. A 4000-card COBOL program compiled as fast as the 1000-card/minute readers could read the code. The program was ready