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Getting Started With Extended Color BASIC
271 pages, Paperback
Published January 1, 1984
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July 31, 2019
This is a breezy introduction to Extended Color BASIC on the Color Computer 2 (and the Deluxe Color Computer which, while it never made it to market, is referenced in this guide).
It’s a strange combination of extreme basics and very advanced. While most of the book covers building BASIC programs up in extreme detail, chapter 34, “Using Machine Language Subroutines” jumps straight into assembly, assuming you already know it.
And the entry on the DEF FN statement, to create simple functions,
What’s the point of calling it a variable list, and defining it as “one dummy variable for each variable to be used by the function”? Presumably that some versions of DEF FN on other computers do allow a variable list and the author(s) wanted to be comprehensive.
And yet the list of BASIC statements and functions in the appendix is not comprehensive; it’s missing, for example, the DLOAD statement; I noticed this only because DLOAD is one of the two major reasons I was willing to succumb to nostalgia to buy the Color Computer 2 I went through this book using. DLOAD allows downloading BASIC software through the serial port, which will theoretically make it easy to interface the Color Computer with a Raspberry Pi. (The other was that it was both inexpensive and the rare late model that contained true lower case.)
The Color Computer 3 was my second computer. I was never a fan of computers that hooked straight into televisions, and so never regretted choosing the TRS-80 Model 1 as my first computer, despite its lack of color and its even for the time low resolution graphics. In fact I never specifically chose to “upgrade” from the Model 1 to the CoCo 3. I bought the Color Computer from a friend because it came with a hard drive that I could use with the Model 1. But we had a house fire, and since the Model 1 was out, it was fire-damaged, but the Color Computer, stored away in its box, was not.
I don’t recall using Extended Color BASIC at the time—as I recall I moved immediately or nearly so to Microware’s OS-9 Unix-like OS for the Color Computer 3, after which it was difficult to survive without multitasking and an ultramodern BASIC language. So much of what I learned from this book was a pleasant surprise. Despite its, for today, primitive sound and graphics, ECB made it easy to use them. There’s even a freeform “PLAY” command that allows playing music by notes and durations.
That’s the first line from “When the saints go marching in”—if you’re familiar with the song you’ll recognize it from the notes, C, E, F, G, repeated. T changes the tempo, P is a rest (it stands for pause, why they didn’t use R I don’t know), and L for note length. The default is L4 (quarter notes) and L1 is a whole note. L8 would be an eighth note, and so on, and if you wanted to get real jazzy any number from 1 to 255 is possible, so seventh notes are perfectly reasonable.
I literally just wrote a similar script for the Macintosh in 42 Astoundingly Useful Scripts and Automations for the Macintosh; except for tempo and the use of semicolons for separators, I was able to verify this melody using the notes and durations as given.
What this meant was that music could be played by building up human-readable strings instead of the more common numerical representations (which ECB also supported).
And there was a similar mechanism for drawing. ECB supports various statements for drawing lines, boxes, and circles but it also supports a “DRAW” statement:
B means blank; M means move to location 128,96; U means go up 25 points, R means go right 25 points, D means down 25 points, and L left 25 points, thus drawing a box. It can change direction by angles and even change the scale of the drawing, making it a snap to draw smaller or larger versions of a drawing by manipulating a string of characters.
Interestingly, all of the ECB drawing statements use resolution-independent coordinates. The upper left is 0,0 and the lower right 255,191 regardless of whether you’re in low (128x96), medium (128x192), or high (256x192) resolution. This is an extremely useful feature that I was surprised to see in this early of a computer.
It’s a strange combination of extreme basics and very advanced. While most of the book covers building BASIC programs up in extreme detail, chapter 34, “Using Machine Language Subroutines” jumps straight into assembly, assuming you already know it.
And the entry on the DEF FN statement, to create simple functions,
DEF FN name (variable list) = formula
• name is the name you assign to the function you create
• variable list contains one “dummy variable” for each variable to be used by the function
• formula defines the operation in terms of the variables given in the varriable list
Note: … You may have only one argument in a formula call; therefore, DEF FN must contain only one variable.
What’s the point of calling it a variable list, and defining it as “one dummy variable for each variable to be used by the function”? Presumably that some versions of DEF FN on other computers do allow a variable list and the author(s) wanted to be comprehensive.
And yet the list of BASIC statements and functions in the appendix is not comprehensive; it’s missing, for example, the DLOAD statement; I noticed this only because DLOAD is one of the two major reasons I was willing to succumb to nostalgia to buy the Color Computer 2 I went through this book using. DLOAD allows downloading BASIC software through the serial port, which will theoretically make it easy to interface the Color Computer with a Raspberry Pi. (The other was that it was both inexpensive and the rare late model that contained true lower case.)
The Color Computer 3 was my second computer. I was never a fan of computers that hooked straight into televisions, and so never regretted choosing the TRS-80 Model 1 as my first computer, despite its lack of color and its even for the time low resolution graphics. In fact I never specifically chose to “upgrade” from the Model 1 to the CoCo 3. I bought the Color Computer from a friend because it came with a hard drive that I could use with the Model 1. But we had a house fire, and since the Model 1 was out, it was fire-damaged, but the Color Computer, stored away in its box, was not.
I don’t recall using Extended Color BASIC at the time—as I recall I moved immediately or nearly so to Microware’s OS-9 Unix-like OS for the Color Computer 3, after which it was difficult to survive without multitasking and an ultramodern BASIC language. So much of what I learned from this book was a pleasant surprise. Despite its, for today, primitive sound and graphics, ECB made it easy to use them. There’s even a freeform “PLAY” command that allows playing music by notes and durations.
PLAY "T5;C;E;F;L1;G;P4;L4;C;E;F;L1;G"
That’s the first line from “When the saints go marching in”—if you’re familiar with the song you’ll recognize it from the notes, C, E, F, G, repeated. T changes the tempo, P is a rest (it stands for pause, why they didn’t use R I don’t know), and L for note length. The default is L4 (quarter notes) and L1 is a whole note. L8 would be an eighth note, and so on, and if you wanted to get real jazzy any number from 1 to 255 is possible, so seventh notes are perfectly reasonable.
I literally just wrote a similar script for the Macintosh in 42 Astoundingly Useful Scripts and Automations for the Macintosh; except for tempo and the use of semicolons for separators, I was able to verify this melody using the notes and durations as given.
$ piano -c e f 1 g 4 r -c e f 1 g
What this meant was that music could be played by building up human-readable strings instead of the more common numerical representations (which ECB also supported).
And there was a similar mechanism for drawing. ECB supports various statements for drawing lines, boxes, and circles but it also supports a “DRAW” statement:
25 DRAW "BM128,96;U25;R25;D25;L25"
B means blank; M means move to location 128,96; U means go up 25 points, R means go right 25 points, D means down 25 points, and L left 25 points, thus drawing a box. It can change direction by angles and even change the scale of the drawing, making it a snap to draw smaller or larger versions of a drawing by manipulating a string of characters.
Interestingly, all of the ECB drawing statements use resolution-independent coordinates. The upper left is 0,0 and the lower right 255,191 regardless of whether you’re in low (128x96), medium (128x192), or high (256x192) resolution. This is an extremely useful feature that I was surprised to see in this early of a computer.
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