compiler was based on the Blue Label Pascal compiler originally produced for the NasSys cassette-based operating system of the Nascom microcomputer in 1981 by Anders Hejlsberg. Borland licensed Hejlsberg's "PolyPascal" compiler core (Poly Data was the name of Hejlsberg's company in Denmark), and added the user interface and editor. Anders Hejlsberg joined the company as an employee and was the architect for all versions of the Turbo Pascal compiler and the first three versions of Borland Delphi. The compiler was first released as Compas Pascal for CP/M, and then released on 20 November 1983 as Turbo Pascal for CP/M (including the Apple II computer when fitted with a Z-80 SoftCard, effectively converting the 6502-based Apple into a CP/M machine, the Commodore 64 with CP/M cartridge, and the later DEC Rainbow), CP/M-86, and DOS machines. On its launch in the United States market, Turbo Pascal retailed for , a very low price for a compiler at the time. The integrated Pascal compiler was of good quality compared to other Pascal products of the time. The Turbo name alluded to the speed of compiling and of the executables produced. The edit/compile/run cycle was fast compared to other Pascal implementations because everything related to building the program was stored in RAM, and because it was a one-pass compiler written in assembly language. Compiling was much faster than compilers for other languages (even Borland's own later compilers for C), and other Pascal compilers, and programmer time was also saved since the program could be compiled and run from the IDE. The execution speed of these COM-format programs was a revelation for developers whose only prior experience programming microcomputers was with interpreted BASIC or UCSD Pascal, which compiled to p-code which was then interpreted at runtime. Unlike some other development tools, Turbo Pascal disks had no copy protection. Turbo Pascal came with the "Book License": "You must treat this software just like a book ... [it] may be used by any number of people ... may be freely moved from one computer location to another, so long as there is no possibility of it being used at one location while it's being used at another." Reception Borland sold about 250,000 copies of Turbo Pascal in two years, which Bruce F. Webster of Byte described as "an amazing figure for a computer language". He reported six months later that the figure had risen to "more than