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--- sd-8516_user_s_guide [2026/02/20 21:00] – appledog
+++ sd-8516_user_s_guide [2026/02/21 10:20] (current) – appledog
@@ Line 15: / Line 15: @@
 Type this right now (press ENTER after the line):
-    ? "HELLO WORLD"
+<codify BASIC>
+? "HELLO WORLD"
+</codify>
 The computer should immediately display:
@@ Line 23: / Line 25: @@
 Now try:
-    ? 42 + 8
+<codify BASIC>
+? 42 + 8
+</codify>
 It prints 50. You can do math right away, no program needed. This is called **direct mode,** directly entering commands on the terminal.
@@ Line 34: / Line 38: @@
 Now carefully type these lines (press ENTER after each one):
- ? "HELLO WORLD"
+<codify BASIC>
-GOTO 10
+ PRINT "HELLO WORLD"
+GOTO 10
+</codify>
 Type **RUN** and press ENTER.
@@ Line 48: / Line 54: @@
 You don't have to type lines in order, the computer will sort them for you automatically. Try this:
-? "LINE 20 COMES FIRST ANYWAY!"
+<codify BASIC>
-? "BUT LINE 10 RUNS FIRST"
+? "LINE 20 COMES FIRST ANYWAY!"
+? "BUT LINE 10 RUNS FIRST"
+</codify>
 **RUN**
@@ Line 67: / Line 75: @@
 Try this in direct mode:
-    LET A = 25
+<codify BASIC>
+LET A = 25
-    ? A
+? A
+</codify>
 It prints 25.
@@ Line 75: / Line 85: @@
 Now a tiny counting program:
-LET A = 1
+<codify BASIC>
-? A
+LET A = 1
-LET A = A + 1
+? A
-IF A <= 10 THEN GOTO 20
+LET A = A + 1
-? "BLAST OFF!"
+IF A <= 10 THEN GOTO 20
+? "BLAST OFF!"
+</codify>
 **RUN**
@@ Line 110: / Line 122: @@
 Add these lines to make a simple checker:
-IF E = 42 THEN GOTO 70
+<codify BASIC>
-IF E <> 42 THEN ? "TRY AGAIN!"
+IF E = 42 THEN GOTO 70
-GOTO 10
+IF E <> 42 THEN ? "TRY AGAIN!"
-PRINT "YOU FOUND THE ANSWER!"
+GOTO 10
+PRINT "YOU FOUND THE ANSWER!"
+</codify>
 **RUN** and try a guess until you hit 42. (42 is a reference to the Hitchhiker's Guide -- a great book).
@@ Line 158: / Line 172: @@
 Here is an example program:
-LET A = 5
+<codify BASIC>
-PRINT A
+LET A = 5
-LET A = A - 1
+PRINT A
-IF A > 0 THEN GOTO 20
+LET A = A - 1
-PRINT "GOAL!"
+IF A > 0 THEN GOTO 20
+PRINT "GOAL!"
+</codify>
 Next, type **RUN.** You will see a countdowns to 1, then "GOAL!"
@@ Line 173: / Line 189: @@
 Here is an example of a GOSUB helper function:
-REM GOSUB SQUARE DEMO
+<codify BASIC>
-LET A = 2
+REM GOSUB SQUARE DEMO
-GOSUB 1000
+LET A = 2
-LET A = 3
+GOSUB 1000
-GOSUB 1000
+LET A = 3
-LET A = 4
+GOSUB 1000
-GOSUB 1000
+LET A = 4
-LET A = 5
+GOSUB 1000
-GOSUB 1000
+LET A = 5
-GOTO 9000
+GOSUB 1000
-REM END
+GOTO 9000
+REM END
 REM THIS HELPER FUNCTION WILL PRINT THE SQUARE OF A
 PRINT A * A
 RETURN
+</codify>
 After you enter this program and type RUN, you will see the result 4, 9, 16, 25. As you can see, every time the program calls **GOSUB 1000,*** it runs the code at LINE NO 1000 and then **RETURN**s to continue in the main program.
@@ Line 199: / Line 217: @@
 **NEW** then type:
- ? ""
+<codify BASIC>
+ PRINT ""
 GOSUB 900   : REM SHOW INSTRUCTIONS
 A=1 : B=100
@@ Line 244: / Line 263: @@
 RETURN
 REM END
+</codify>
-Ty to **RUN** this program and play a few rounds! The subroutines make it modular. If you want fancier win/lose messages later, just edit those GOSUB lines.
+Try to **RUN** this program and play a few rounds! The subroutines make it modular. If you want fancier win/lose messages later, just edit those GOSUB lines.
 **Negative Numbers in Action**
@@ Line 251: / Line 271: @@
 Since negatives are fully supported, try tweaking the game or make a countdown timer:
+<codify BASIC>
 PRINT "COUNTDOWN FROM ZERO..."
 LET A = 0
@@ Line 257: / Line 278: @@
 IF A >= - 10 THEN GOTO 30
 PRINT "BLAST OFF INTO NEGATIVE SPACE!"
+</codify>
+=== WHILE, DO-WHILE, and FOR-NEXT Part I
+Stellar BASIC V1 keeps things simple and fast; no built-in FOR-NEXT or WHILE (yet! --they're coming in future updates). But you can create powerful repeating loops using just IF...THEN and GOTO, plus a counter variable when needed. This section will demonstrate the kind of clever thinking you will need to write advanced programs in TinyBASIC.
+The key tricks:
+* WHILE -- A while loop checks the condition first, so place the IF check before the loop body.
+* DO-WHILE -- A do loop runs at least once, so place the IF check at the end of the loop body.
+* FOR-NEXT -- A for-next is essentially a WHILE loop (see below).
+Let's see these in action with short examples you can type in right now.
+==== WHILE
+WHILE is short for WHILE-DO. The loop check is at the front of the do-loop (so it may skip the loop entirely). This is like "while something is true, keep doing the body."
+Example: Print numbers from 1 to 5, checking first.
+<codify BASIC>
+LET I = 1
+IF I > 5 THEN GOTO 60
+? I
+LET I = I + 1
+GOTO 20
+? "DONE!"
+</codify>
+This prints 1 through 5. If you change line 10 to LET I=10, it skips the printing entirely, since the condition was false when we checked the loop condition (at the front of the loop body).
+==== DO-WHILE
+In this style the do-loop is executed and then if the condition (the while) passes, it executes the loop again. This style of loop always runs at least once.
+Example: Keep asking for a positive number until you get one.
+<codify BASIC>
+INPUT "ENTER A POSITIVE NUMBER ", N
+IF N > 0 THEN GOTO 40
+PRINT "TRY AGAIN – MUST BE POSITIVE!"
+IF N <= 0 THEN GOTO 10
+PRINT "THANKS! YOU ENTERED "; N
+</codify>
+This program runs the INPUT at least once. If you enter -5, it complains and loops back. If positive, it exits. The check is at the bottom; no skip on first pass.
+==== FOR-NEXT
+Here, the FOR idea is to iterate over a range, and the NEXT check usually occurrs at the front of the loop (but may also occurr at the end of the loop).
+Example: Countdown from 10 to 0, check at top.
+<codify BASIC>
+LET C = 10
+IF C >= 0 THEN GOTO 40
+GOTO 70
+PRINT C
+LET C = C - 1
+GOTO 20
+PRINT "IGNITION!"
+</codify>
+Observe that sometimes flipping the logic of the test makes the code cleaner (no extra check):
+<codify BASIC>
+LET C = 10
+IF C < 0 THEN GOTO 60
+PRINT C
+LET C = C - 1
+GOTO 20
+PRINT "IGNITION!"
+</codify>
+In this second case, inverting the logic falls-through to the do-loop. This is more efficient, even though the idea is "if C is greater than or equal to zero". Know your logic operators!
+==== FOR-NEXT part II
+Here is another example of a similar loop, that amounts to a FOR-NEXT loop.
+Example: Print even numbers 2 to 20 (step +2).
+<codify BASIC>
+LET X = 2
+IF X > 20 THEN GOTO 60
+PRINT X
+LET X = X + 2
+GOTO 20
+PRINT "EVEN NUMBERS DONE!"
+</codify>
+Or, to simulate STEP -1 (countdown), as before,
+<codify BASIC>
+LET Y = 20
+IF Y < 1 THEN GOTO 60
+PRINT Y
+LET Y = Y - 1
+GOTO 20
+PRINT "BLAST OFF!"
+</codify>
+These methods of program flow control are from old-school TinyBASIC programming. This was the norm -- inventive uses of code. There is a LOT you can do with TinyBASIC. It's understandable, and very efficient.
+=== An Exercise for the Reader
+You can practice your BASIC skills with these exercises:
+* Make the WHILE example count backwards.
+* Turn the guessing game's round counter into a DO-style loop (run at least one round?).
+* Add a "Play again?" wrapper around your game.
+When FOR-NEXT arrives in a future update, you'll appreciate how these hand-built loops taught you control flow. Until then, don't forget to "think differently!"
 == NEXT STEPS
@@ Line 266: / Line 395: @@
 //Check the **SD-8516 Programmer's Reference Guide** for deeper details including a roadmap for upcoming FOR-NEXT loops, PEEK/POKE for peeking at memory (classic retro fun), string variables (A$), sound commands, and more.//