Hello World Tutorial - Revision history

Mr z: /* Cartridge Header */

2011-11-18T06:09:59Z

‎Cartridge Header

Mr z: Protected "Hello World Tutorial" ([edit=autoconfirmed] (indefinite) [move=autoconfirmed] (indefinite))

2010-12-04T08:33:52Z

Protected "Hello World Tutorial" ([edit=autoconfirmed] (indefinite) [move=autoconfirmed] (indefinite))

Mr z: /* Calling PRINT */

2008-09-08T15:44:58Z

‎Calling PRINT

Mr z: /* A note on INCLUDE */

2007-11-02T05:29:24Z

‎A note on INCLUDE

Mr z at 22:23, 8 October 2007

2007-10-08T22:23:04Z

Mr z: /* Next Steps */

2007-10-07T19:47:42Z

‎Next Steps

Mr z: /* Cartridge Header */

2007-10-07T09:04:59Z

‎Cartridge Header

Mr z: /* ROM Width and Origin */

2007-10-07T09:04:21Z

‎ROM Width and Origin

Mr z: /* Assembling and Running */

2007-10-07T09:03:14Z

‎Assembling and Running

Mr z: /* Calling PRINT */

2007-10-07T08:57:50Z

‎Calling PRINT

@@ Line 76: / Line 76: @@
 <TR><TD>bit 15..10</TD><TD>Unused.</TD></TR>
 <TR><TD>bit 9..8</TD><TD>Unknown.  Set both to 1 to skip ECS title screen.</TD></TR>
-<TR><TD>bit 7</TD><TD>Run code that appears after title screen.</TD></TR>
+<TR><TD>bit 7</TD><TD>Run code that appears after title string.</TD></TR>
 <TR><TD>bit 6</TD><TD>Set to 1 to work on Intellivision 2.</TD></TR>
 <TR><TD>bit 5..0</TD><TD>What inputs the EXEC will make "click" sounds for</TD></TR>

@@ Line 186: / Line 186: @@
 == Calling PRINT ==
-The SDK-1600 PRINT function accepts its arguments multiple ways.  Take a look at [http://sdk-1600.spatula-city.org/examples/library/print.asm examples/library/print.asm] in SDK-1600 for a complete listing.  For now, we will use the "PRINT.FLS" variant, which expects the following:
+The SDK-1600 PRINT function accepts its arguments multiple ways.  Take a look at [[print.asm]] in SDK-1600 for a complete listing.  For now, we will use the "PRINT.FLS" variant, which expects the following:
 <CODE><pre>
 ;;  PRINT.FLS     Format, location, and string itself follows CALL          ;;

@@ Line 269: / Line 269: @@
 If you're accustomed to programming in a language like C or C++, you are now probably wondering "Why do I put the INCLUDE line at the end rather than the beginning?"  That's a great question!
-The INCLUDE directive copies in the contents of the specified file at the exact location it appears in your source file.  It's as if you cut and pasted that file in at that point.  The file "print.asm" contains the actual assembly code for the PRINT function.  That means that the code gets assembled *right there*.
+The INCLUDE directive copies in the contents of the specified file at the exact location it appears in your source file.  It's as if you cut and pasted that file in at that point.  The file "print.asm" contains the actual assembly code for the PRINT function.  That means that the code gets assembled ''right there''.
 In a C or C++ program, the #include directive works similarly in that it copies in the requested file.  The difference is that C and C++ header files typically only contain declaration information.  They don't actually contain the program code that implements the functions you'll call.  For example, when you do a "<CODE>#include &lt;stdio.h&gt;</CODE>", the file stdio.h describes what printf() looks like, but doesn't actually have an implementation of printf() in there.  That comes from a library somewhere.  That library gets linked in later.

← Older revision		Revision as of 22:23, 8 October 2007
Line 1:		Line 1:
		+	[[Category: Programming]][[Category: Tutorial]]
		+
	This tutorial serves as a quick-start, quickly introducing a simple program that displays the famous phrase "Hello World" on an Intellivision title screen. In this tutorial, you will see how to invoke the assembler and how to call a library function from [http://sdk-1600.spatula-city.org/ SDK-1600] named [http://sdk-1600.spatula-city.org/examples/library/print.asm PRINT]. This particular tutorial does not go into all the details underlying how it works. Dig into the more specific tutorials for deeper dives on all the topics this example touches.		This tutorial serves as a quick-start, quickly introducing a simple program that displays the famous phrase "Hello World" on an Intellivision title screen. In this tutorial, you will see how to invoke the assembler and how to call a library function from [http://sdk-1600.spatula-city.org/ SDK-1600] named [http://sdk-1600.spatula-city.org/examples/library/print.asm PRINT]. This particular tutorial does not go into all the details underlying how it works. Dig into the more specific tutorials for deeper dives on all the topics this example touches.

← Older revision		Revision as of 19:47, 7 October 2007
Line 290:		Line 290:

	See if you can take what you've learned and modify the title screen even more. For instance, try replacing "Mattel Electronics" with something else. Good luck!		See if you can take what you've learned and modify the title screen even more. For instance, try replacing "Mattel Electronics" with something else. Good luck!
		+
		+	----
		+	Back to [[Programming Tutorials]].

← Older revision	Revision as of 08:33, 4 December 2010
(No difference)

@@ Line 80: / Line 80: @@
 You can ignore bits 5..0 if you don't use the EXEC.  The "keyclick" functionality only works if you rely on the EXEC for keypad input.  None of my programs uses the EXEC.
-There is a third field of interest, "MAIN".  If you bypass the EXEC as I do, and don't rely on the EXEC to show your title screen for you, then this field is never actually used.  Otherwise, this field points to the first line of program code that the EXEC will call after the user dismisses the EXEC's title screen.
+There is a third field of interest, "MAIN".  If you bypass the EXEC as I do, and don't rely on the EXEC to handle starting the game after the title screen, then this field is never actually used.  Otherwise, this field points to the first line of program code that the EXEC will call after the user dismisses the EXEC's title screen.
 As shown, the header above will bypass most of the EXEC's automatic setup, which is fine.  None of my examples will rely on the EXEC to do anything.  (Well, other than put up the title screen in this case.)  This brings us to the next piece of code, the date and title.

@@ Line 41: / Line 41: @@
-The "ORG" directive sets the current "origin".  What is this, and why does it matter?  The assembler is not a compiler.  Compilers take high level code, rearrange it and translate it, and ultimately bake it down into a series of instructions that run on the CPU.  An assembler does much, much less than that.  It merely assembles (as in "puts together") what you've written.  The assembler internally keeps an image of what should be in memory based on what you've told it.  When the assembler starts, that image is empty.  As you give it instructions to assemble, the assembler converts these to machine code and inserts them into this virtual memory image.  The ORG directive tells it where to start writing.
+The "ORG" directive sets the current "origin".  What is this, and why does it matter?  The assembler is not a compiler.  Compilers take high level code, rearrange it and translate it, and ultimately bake it down into a series of instructions that run on the CPU.  An assembler does much, much less than that.  It merely assembles (as in "puts together") what you've written.  The assembler internally keeps an image of what should be in memory based on what you've told it.  When the assembler starts, that image is empty.  As you give it instructions to assemble, the assembler converts these to machine code and inserts them into this virtual memory image.  The ORG directive tells it where to start writing&mdash;a "cursor," if you will.
-A program can have more than one ORG statement.  The ORG statement moves the assembler's "cursor" (aka. the "SPC" or "Section Program Counter"), to a new spot.  This is useful in cases where not all of your ROM is contiguous.  That's a topic for another tutorial.
+A program can have more than one ORG statement.  The ORG statement moves the assembler's cursor (aka. the "SPC" or "Section Program Counter"), to a new spot.  This is useful in cases where not all of your ROM is contiguous.  That's a topic for another tutorial.
 So why "<CODE>ORG $5000</CODE>"?  The Intellivision's [[Executive ROM|EXEC]] expects most cartridges to start at this address.  It looks for a cartridge header there, and expects that header to tell it something interesting and useful about the program, which leads us to the next part of the program, the cartridge header.

@@ Line 120: / Line 120: @@
 <TR><TD>hello1.lst</TD><TD>The listing file</TD></TR>
 </TABLE>
-You can now run hello1.rom or hello1.bin in your favorite Intellivision emulator or on a real Intellivision by way of a Cuttle Cart 3, Intellicart, Foom Board or any other hardware that happens to let you run on the real hardware.  You should see:
+You can now run hello1.rom or hello1.bin in your favorite Intellivision emulator or on a real Intellivision by way of a [http://www.schells.com/cc3.shtml Cuttle Cart 3], Intellicart, Foom Board or any other hardware that happens to let you run on the real hardware.  You should see:
 <CENTER>[[Image:Hello1 scrshot.gif|hello1.asm screen shot]]</CENTER>
 (Note:  The screen will look different if you run this on a Sears machine, since the Sears units omit the "Mattel Electronics" string.)

@@ Line 205: / Line 205: @@
 The "pointer to display location" is the address on the display to which PRINT will print the string.  Display memory starts at location <CODE>$200</CODE>.  Location <CODE>$200</CODE> corresponds to the upper left hand corner.  Each row is 20 characters long.  Thus, <CODE>$200 + 19</CODE> is the rightmost character in the top row, and <CODE>$200 + 20</CODE> is the leftmost character in the second row.  I'll refer to the top row as row 0 and the leftmost column as column 0.  This makes the math easier.
-We wish to replace the "Copr @ 19:7 Mattel" string at the bottom of the screen with our own.  If you look closely at the screen you'll see that it begins in row 10, column 1.  The address of this location is given by the expression:  <CODE>$200 + 10*20 + 1</CODE>.
+<CENTER>[[Image:Hello1_scrshot_grid.gif]]</CENTER>
 The assembler will evaluate expressions for you, so you can put that entire expression in there as-is and let the assembler work it out for you.  It makes the code easier to understand and easier to write.  Also, in some cases, it can make otherwise very complex and tricky things easy, especially if it all gets hidden in a macro.  But that's for a later tutorial.