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A Revolutionary Concept in High-Level Languages
No one would dispute the value of a program that is small and fast. Compiler vendors, such as Microsoft and Borland are constantly refining their products to improve the performance and size of your programs. Unfortunately, no high-level language even comes close to creating programs as efficient as those written in assembly language. That is, until now.
This remarkable library lets you write programs that are extremely fast and compact, using a high-level language you already know. Unlike C, Pascal, or regular compiled BASIC, P.D.Q. can produce a "Hello world" program with a stand-alone .EXE file size of less than 900 bytes. Real programs that perform useful tasks may be written in less than 2,000 bytes. For example, P.D.Q. includes a sample setup program for Epson printers with an .EXE file size of 1,900 bytes. Programs produced by P.D.Q. are typically half the size of an equivalent written in C. P.D.Q. is truly the closest you'll get to a pure assembler program, but without having to code in assembly language.
The primary purpose of P.D.Q. is for writing small to medium-sized applications, where program size and execution speed are critical. A wealth of string, DOS, and BIOS services are provided, along with full support for modern programming constructs. Best of all, TSR programming and interrupt handling are built into the P.D.Q. library. You can create complete memory-resident applications in just minutes, instead of days or even weeks. TSR capabilities are added by using four simple subroutine calls. The P.D.Q. routines then handle all the details of memory allocation, the DOS "busy flag," deinstallation, and so forth. A P.D.Q. program can even intercept multiple interrupts if needed, with separate program entry points for each. Without doubt, P.D.Q. is the most exciting concept in high-level languages to come along in years.
As Easy as BASIC
P.D.Q. is a replacement linking library for use with Microsoft's QuickBASIC, PDS, and VB/DOS compilers. You simply compile your programs with BC.EXE as usual and then link it with the P.D.Q. library file. By completely rewriting the BASIC language library, we were able to greatly improve the efficiency of the resultant code. All of the "hand-holding" BASIC normally adds to every program has been removed, leaving only the essential elements. Therefore, you can be productive immediately, without having to struggle to learn a new language.
We also overhauled BASIC's convoluted method of handling DOS errors. Where conventional BASIC requires you to first define an error handler and then set up an ON ERROR trap to jump there, P.D.Q. lets you simply test the success or failure of the most recent DOS operation, as this short program fragment illustrates:
OPEN "ACCOUNTS.DAT" FOR INPUT AS #1
IF ERR = 53 THEN PRINT "Sorry, file not found."
The Spirit of Performance
Our goal in designing P.D.Q. was to place code size and execution speed above all other considerations. Many programmers mistakenly believe that compiled languages are inherently large and slow, but nothing could be further from the truth. In many cases, Microsoft's BASIC compilers generate object code as efficient as a human hand-coding in assembly language. The real difficulty with most compilers is the way their language libraries are implemented. By taking an entirely new approach to language design, P.D.Q. can create programs that are nearly as small and fast as those written in assembly language.
Like most compilers, Microsoft BASIC translates simple program statements directly to the equivalent machine-code. For example, X% = X% + 1 is compiled by BASIC to INC WORD PTR [X%]. However, more complex commands, such as OPEN, MID$, and CLS, generate calls to the BASIC language library. And that's where P.D.Q. comes in. All of the BASIC language routines in the P.D.Q. library are extremely efficient and have been optimized to the fewest number of bytes and machine clock cycles.
But Isn't That What C is For?
One of the promises of C was to provide smaller and faster programs, in exchange for additional programming effort. If you were willing to step down to a lower level language, nearer to assembler, the compiler would reciprocate by generating a more efficient program. But this simply isn't true - current C compilers offer little if any improvement over compiled BASIC. In fact, compared to P.D.Q. C is just another slow and bloated high-level language! Further, many people will agree that C programs are notoriously difficult to write, and even harder to debug. By contrast, P.D.Q. is as easy as BASIC because it is BASIC, while providing a level of performance clearly superior to C. And everyone knows that performance is what programming is all about.
How We Did it
In order to achieve such impressive file sizes and high performance, we did have to make some compromises. Many of BASIC's advanced math and graphics statements are not supported, and in some cases a slight amount of additional programming effort is required. However, all of BASIC's powerful string handling features are available, and dozens of useful language extensions are also provided. In all, 165 BASIC statements and keywords are supported. Please remember that P.D.Q. is intended mainly as an alternative to writing in assembly language, and as such it is extremely powerful and easy to use.
Even without BASIC's most advanced features, many useful and varied programs may be written using P.D.Q. These include DOS utilities, TSR printer drivers, pop-up calculators and help programs, DOS shells, screen capture utilities, and Install programs. Many such examples are included with P.D.Q. along with full source code.
Seeing is Believing
The benchmark timings below were made on a 386-25 computer but slowed down to 8 MHz. to obtain repeatable results. A RAM disk was used for the read/write timings. All file sizes are in bytes, and all times are in seconds.
The NumOff utility turns the NumLock key off, and the Hello program simply prints "Hello" - these show the effective minimum program size for each language system. Note that the P.D.Q. Hello program includes the entire dynamic string management portion of the runtime library. The DOS filter program accepts input from STDIN, capitalizes it and strips the high bit from each character, and sends the result through STDOUT.
The Epson Setup program is a menu-driven utility that sends escape codes for various printer settings. The TSR version can be popped up over any text-mode program, and it saves and restores the underlying screen. Finally, the .EXE file size program is a clone of Peter Norton's 9k original FS.COM utility. It reads all files whose names match a given specification, adds up their sizes, and also verifies if they will fit onto a selected target drive. Like Norton's, our version also takes the target cluster size into account when determining if the files will fit.
For the long integer multiply test, 150 multiplications were performed in a loop 1,000 times. Please note that the Turbo C programs were compiled using the Small Model, which produces .COM files. Also note that we have optimized long integer operations for size rather than speed. Finally, a bug in the sort routine provided with QuickC is responsible for its poor showing in that category.
.EXE File Size Comparisons
|P.D.Q.||QC 2.0||TC 2.0||TP 5.5||QB 4.5|
|TSR Epson Setup||4,800||n/a||n/a||n/a||n/a|
|File Size Program||4,956||10,537||7,814||8,809||19,650|
Of all the popular language compilers, P.D.Q. clearly provides the smallest .EXE file sizes.
|P.D.Q.||QC 2.0||TC 2.0||TP 5.5||QB 4.5|
|Long Integer Multiply||2.64||2.31||2.25||7.52||3.02|
|Long Integer Multiply (386)||2.20||2.31||2.25||7.52||3.02|
|Sort 3,000 10-byte Strings||0.60||144.89||1.54||0.99||1.92|
|Print 3,000 70-byte Strings||0.88||1.15||1.04||3.52||2.04|
|Write 500 80-byte Records||0.33||0.33||0.66||0.44||0.38|
|Read 500 80-byte Records||0.27||0.27||0.27||0.49||0.28|
As you can see, P.D.Q. is more than competitive with the fastest language compilers.
P.D.Q. is supplied as two library files - PDQ.LIB is intended for use with any IBM PC or compatible computer, and PDQ386.LIB is a 386-specific version for use with 386 or later processors.
Dozens of useful language extensions are provided, including memory allocation; DOS critical error trapping; block memory moves; a string array sort; a complete set of TSR extensions with optional swapping to EMS or disk; output through STDERR; access to the parent environment, and much more. Many examples and complete utilities are included, as well as a comprehensive owner's manual. The manual documents every BASIC internal routine and shows how to use P.D.Q. as a toolbox for use with assembly language. This remarkable product has revolutionized BASIC programming and has received countless outstanding reviews. The original 1.0 version was awarded Byte Magazine's User Choice Award for language of the year in 1990.
As with all our products, full source code is provided at no additional cost, so you can see how the routines were designed and even modify them if you want. We genuinely want you to understand how our libraries work and be able to learn from them. All of our products are reasonably priced and include free technical assistance, but they are licensed for use by only one person using one computer at a time. Royalty payments are not required when our routines are incorporated into your compiled applications. However, you may not distribute our source, object, or library files. If your customers need to rebuild your program, they will need their own copy of our product(s).
The Bottom Line
P.D.Q. costs only $149 and works with QuickBASIC 4.x, PDS 7.x, and VB/DOS. Add $8 for UPS ground shipping to US addresses only (no P.O. boxes); Connecticut residents must add 6.0% sales tax or show proof of tax-exempt status when ordering. Please email or call us for overnight and foreign shipping costs. We accept only prepaid orders accompanied by a check.
Download Demo: PDQ.ZIP (31k)
P.D.Q. is a trademark of Crescent Software, Inc.