30 Years Ago: Turbo Pascal, BASIC Turn PCs Into Programming Engines

By Darryl K. Taft  |  Posted 2013-09-05 Print this article Print

"Once we integrated the whole system, we had an almost instantaneous and continuous 'Edit -> Compile -> Run -> Debug -> Edit' productive cycle. The efficiency gains were fantastic. These are the kind of tools that we are building today at Fullpower/MotionX for wearable technology," Kahn said.

Indeed, Kahn told eWEEK he believes "Turbo Pascal was to the original IBM PC what Xcode is to the iPhone: a fast, powerful, efficient, interactive integrated development system." Moreover, "Before Turbo Pascal, all the professional tools that generated executable code on the PC were multi-pass, command-line style compilers," he said. "Turbo Pascal set a new standard and changed all of that."

"Borland made developer tools accessible by selling a complete editor/compiler for an incredibly low price," Mike Sax, founder of Asigo, an accounting software company, said. "I believe it was 10 times cheaper than leading competitors. At least as important, and often overlooked, Borland made tools more accessible by requiring far less memory and disk space than other vendors, combining the editor and the compiler in a single, incredibly efficient executable. These were the days when PCs without hard drives were still common."

Sax knows a bit about development tools and the early software market. He launched and ran a successful software business for years. Sax Software specialized in creating software components to help developers build better software faster.

Borland greatly sped up the development cycle because developers could launch the compiler and eventually their application directly from the editor, Sax said. "In all other systems, you had to edit your code, run the compiler, restart the editor if you had made a typo, and run your app," he said.

"When developing for Windows 1.0, the development cycle was even worse: Edit your code, quit the editor, run the compiler, reboot the computer (Ctrl+Alt+Delete) into Windows, start your app, exit Windows and reboot again, and start the editor," Sax said.

"So Borland's tools weren't just 10 times cheaper; they actually let you develop software 10 times faster. Furthermore, the programs that were written in Turbo Pascal took advantage of the same highly optimized runtime that the compiler/editor itself was using, resulting in very small and fast applications (which was extremely important at the time)."

Like many of the early revolutionary PC products, Turbo Pascal was viewed by many as a toy. But many of the ideas ended up being incorporated in other products. For instance, Microsoft released QuickBasic shortly thereafter, as well as its CodeView visual debugger, Sax said.

The Turbo Pascal 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 Hejlsberg. Borland licensed Hejlsberg's "PolyPascal" compiler core and added the user interface and editor. Poly Data was the name of Hejlsberg's company in Denmark. He then joined Borland as an employee and was the architect for all versions of the Turbo Pascal compiler and the first three versions of Borland Delphi.

"Before embarking on my first Pascal compiler, I had written an interactive (WYSIWYG) editor and a symbolic assembler in Z-80 assembly code for a British kit computer called the NASCOM 2," Hejlsberg explained.

"I actually enjoyed assembly coding and found that I could be very productive and could write code that was really small. The NASCOM came with a 12K Microsoft ROM BASIC, so I decided to write a plug-replacement 12K Pascal environment. It had an interactive editor, a subset Pascal compiler and a runtime library, all written in assembly code, Hejlsberg said.

"The very simple one-pass compiler compiled directly to in-memory machine code or, for large programs, to cassette tape, which you could then rewind and reload later. Having the editor and compiler in a single integrated IDE was just the natural thing to do," he noted.


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