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25 Graphics Programs in Microsoft Basic
Lists programs that create two-dimensional, three-dimensional, and high resolution graphics, as well as animation and advanced graphics effects
150 pages, Hardcover
First published April 1, 1983
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September 23, 2019
This was a sadly disappointing book. A great cover displays the standard graphics tropes of the time, including the ubiquitous sombrero plot in 3d. Given that few computers with Microsoft BASIC on them could display that plot on screen, I expected a lot of printing. What I didn’t expect was that the printing would be handled by machine code.
The blurbs on the dustcover and the introduction in the preface both promise a wide applicability.
I’m not sure it was written with Microsoft BASIC in mind, though. Throughout, the author uses “PRINT CHR$(12);” to clear the video screen; the text includes the note that you can also use “CLS” but that “PRINT CHR$(12); will work on more computers”. While 12 is the ASC() value of pressing the CLEAR key on the TRS-80 Color Computer 2 I have access to, printing CHR$(12) does not clear the screen; nor does it do so on the TRS-80 Model I/III emulator I have available, though that may be a flaw in the emulator.
David Lien’s BASIC Handbook, under the CLS entry, mentions CHR$(24) as a likely alternative to CLS and the enigmatic note that “If CHR$(24) fails (due to nonconformity of some manufacturer’s use of ASCII numbers), try…”; his third edition switches to CHR$(12) or CHR$(26) without the disparaging note. These numbers are all either print controls (12 is a form feed) or terminal controls (24 is CANcel, and 26 is SUBstitute).
I suspect that rather than being written for Microsoft BASIC personal computers, it was written for printing to a printer. And likely a specific printer at that. The moment he gets into talking about hi-res graphics, he notes that all printers are different, without noting what printer (or computer) he’s using:
The Z-80 machine language subroutine is poked in numerically; no assembly code is provided. Almost all of the hi-res versions of the BASIC programs in the book use some form of (presumably Z-80) subroutine to do the printing. So while you can get the BASIC programs to work on just about any BASIC computer, actually running about half of them requires a Z-80 computer.
I ran the initial program, a histogram demonstration, on a Colour Maximite, to take advantage of its 80x36 character display. It was in fact a very useful program for its era, taking arbitrary data in DATA statements and scaling them based on the maximum and minimum to display a histogram using the letter H for the bars.
From there it goes on to show plotting, molecular modeling, and three-dimensional perspective using the Space Shuttle as an example, all in the amazingly crude graphics of the time (even the hi-res was pretty lo-res).
There’s even a neat chessboard with pieces and a discussion on how pieces are created and moved; however, the pieces are created using the special block graphics of the unnamed Z-80 computer, so, again, it’s a series of not-at-all-portable numbers, even between computers using Microsoft BASIC.
It’s moderately interesting for its description of the state of graphics at the time, but it would be more interesting, and far more useful, if it had defined the computer and display hardware it was using and had either eschewed machine code or made the use of machine code a topic.
The blurbs on the dustcover and the introduction in the preface both promise a wide applicability.
The programs, which are written in Microsoft BASIC, may be used with slight changes on any given microcomputer that uses a Microsoft BASIC interpreter for its operating system. They are the best programs in BASIC for their specific application; they do not use functions that are peculiar to a particular manufacturer’s version of BASIC. In short, they are written in the BASIC used by most microcomputers today.
I’m not sure it was written with Microsoft BASIC in mind, though. Throughout, the author uses “PRINT CHR$(12);” to clear the video screen; the text includes the note that you can also use “CLS” but that “PRINT CHR$(12); will work on more computers”. While 12 is the ASC() value of pressing the CLEAR key on the TRS-80 Color Computer 2 I have access to, printing CHR$(12) does not clear the screen; nor does it do so on the TRS-80 Model I/III emulator I have available, though that may be a flaw in the emulator.
David Lien’s BASIC Handbook, under the CLS entry, mentions CHR$(24) as a likely alternative to CLS and the enigmatic note that “If CHR$(24) fails (due to nonconformity of some manufacturer’s use of ASCII numbers), try…”; his third edition switches to CHR$(12) or CHR$(26) without the disparaging note. These numbers are all either print controls (12 is a form feed) or terminal controls (24 is CANcel, and 26 is SUBstitute).
I suspect that rather than being written for Microsoft BASIC personal computers, it was written for printing to a printer. And likely a specific printer at that. The moment he gets into talking about hi-res graphics, he notes that all printers are different, without noting what printer (or computer) he’s using:
Line 1030 assigns one of the pins on a dot matrix printer to be used in the printing. Again all printers are not alike. Line 1040-1060 poke a Z-80 machine language subroutine into a reserved section of memory. The rest of this subroutine simply sends the array, VA, to the printer line by line. Don’t be overly concerned about understanding it.
The Z-80 machine language subroutine is poked in numerically; no assembly code is provided. Almost all of the hi-res versions of the BASIC programs in the book use some form of (presumably Z-80) subroutine to do the printing. So while you can get the BASIC programs to work on just about any BASIC computer, actually running about half of them requires a Z-80 computer.
I ran the initial program, a histogram demonstration, on a Colour Maximite, to take advantage of its 80x36 character display. It was in fact a very useful program for its era, taking arbitrary data in DATA statements and scaling them based on the maximum and minimum to display a histogram using the letter H for the bars.
From there it goes on to show plotting, molecular modeling, and three-dimensional perspective using the Space Shuttle as an example, all in the amazingly crude graphics of the time (even the hi-res was pretty lo-res).
There’s even a neat chessboard with pieces and a discussion on how pieces are created and moved; however, the pieces are created using the special block graphics of the unnamed Z-80 computer, so, again, it’s a series of not-at-all-portable numbers, even between computers using Microsoft BASIC.
It’s moderately interesting for its description of the state of graphics at the time, but it would be more interesting, and far more useful, if it had defined the computer and display hardware it was using and had either eschewed machine code or made the use of machine code a topic.
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