Earlier this month, I received a message on my Sub-Etha Software Facebook page from author (and former/current CoCo programmer) Carl England:

I knew CHR$(13) was a carriage return, so this was creating a file name that contained carraige returns. What would that do?

I typed it in to find out…

How appropriate, because the first thing I said when i saw this code was “weird.”

Of course, now I have a file on my disk that would be hard to delete. Carl said just doing:

KILL A$

…would take care of it. Provided, of course, you did that after running the program, while A$ still existed. Otherwise you’d have to manually type that line again and replace the SAVE with KILL.

Fun.

Character 8 is a backspace, so I could sorta see what this was doing. “TEST” then four backspaces, then a period, then three more backspaces?

Well.

Also weird.

I could have had so much fun with this trick back when I was swapping disks with friends.

Thanks, Carl!

In 1987, I wrote a simple routine to display a pop-up window on the 32-column text screen of the CoCo. I am not sure what I wrote this for, but it appears I did use this routine (or a version of it) in my TIDY DISK program a year later:

It is sometimes interesting to look back on something I did 35 years ago and see how (or if) I would do it differently today. So let’s do that.

On the Color Computer Archive site is a disk image containing two versions of this routine. The first was done on 8/8/1987, and it looks like a 1.1 was created the next day. I am pleased to see I was retaining versions back then.

Using the wonderful toolshed utility decb, I was able to get a text version of the tokenized BASic program easily:

$decb dir WNDO.DSK
Directory of: WNDO.DSK,

WNDO     BAS  0  B  1
WNDO11   BAS  0  B  1

$decb list -t WNDO.DSK,WNDO.BAS
999 END
1000 REM WINDOW SUBROUTINE
1001 REM S-START W-IDTH
1002 REM A$-TEXT L-ENGTH
1005 PRINT@S,STRING$(W+1,140)CHR$(141);:FORA=1TOL:PRINT@A*32+S,CHR$(133)STRING$(W,32)CHR$(128);:NEXTA:PRINT@32*L+S,CHR$(131)STRING$(W+1,128);:B=1
1010 FORA=W TOW-8STEP-1:IFMID$(A$,A,1)=" "THENPRINT@S+1+32*B,LEFT$(A$,A);:A$=RIGHT$(A$,LEN(A$)-A)ELSENEXTA:PRINT@S+1+32*B,A$;:GOTO1020
1015 B=B+1:GOTO1010
1020 PRINT@S+32*(L-1)+(W/2-5),"press any key";
1025 IFINKEY$=""THEN1025ELSERETURN

$ decb list -t WNDO.DSK,WNDO11.BAS
999 END
1000 REM WINDOW SUBROUTINE 1.1
1001 REM  BY ALLEN C. HUFFMAN
1002 REM      8/8, 8/9/87
1003 C=4
1005 PRINT@S,CHR$(140)STRING$(W,140)CHR$(141);:FORA=1TOL:PRINT@A*32+S,CHR$(133)STRING$(W,32)CHR$(133+16*C);:NEXTA:PRINT@32*L+S,CHR$(131)STRING$(W,131+16*C)CHR$(135+16*C);:B=1
1010 FORA=W TOW-8STEP-1:IFMID$(A$,A,1)=" "THENPRINT@S+1+32*B,LEFT$(A$,A);:A$=RIGHT$(A$,LEN(A$)-A)ELSENEXTA:PRINT@S+1+32*B,A$;:GOTO1020
1015 B=B+1:GOTO1010
1020 PRINT@S+32*(L-1)+W/2-6,"press"CHR$(128)"any"CHR$(128)"key";
1025 IFINKEY$=""THEN1025ELSERETURN

It appears the first version had help in the comments, and the second replaced that with my name and version dates. Looking at a WinMerge diff of the two versions, I see this:

It looks like I basically added color support rather than just a black drop shadow, and must have fixed a bug where width needed 1 added to it. The only other change was printing “PRESS ANY KEY” with black blocks between each word in stead of spaces. I can therefore tell I used at least this 1.1 version in my TIDY DISK program.

The subroutine requires the user to set a few variables before calling it:

• S – PRINT @ position for the top left of the pop-up.
• W – width of the pop-up (in characters).
• L – length (height) of the pop-up (in lines).
• A$ – message to display inside the pop-up. The message will be word-wrapped by the routine.

It appears I also allowed the user to set the color. In line 1003, the routine sets it to 3 (white), but the user could also set C ahead of time and then GOSUB to 1005 to bypass that line and use their own color. So I’ll add:

• C – color of the drop shadow (use GOSUB 1005) if setting C.

GOSUB 1000 uses a default color, or set it yourself and GOSUB 1005. Nice.

10 C=6:S=39:W=16:L=10
20 A$="HELLO, 1987. THIS IS A COCO WINDOW POP-UP."
30 GOSUB 1005

The routine itself is not very smart. It doesn’t calculate anything. The user has to specify top left, width and height and do all that work. If you want a nicely centered box, you have to figure that out. But, if you wanted to make windows at different positions, I guess it allowed that flexibility. (I expect that’s why I wrote it this way.)

We can do better.

How many lines is it, anyway?

For most uses, a centered pop-up seems good enough. The issue is knowing how many lines the message is going to take to display after being word-wrapped. The current routine scans the string starting at “width” and moving backwards until it finds a space character. It then uses LEFT$ to print just that portion, and then trims that part off using RIGHT$.

To know how many lines it will take, we have to scan the string first to count them. Then we do it again to print them. This will slow things down, but make things easier on the user.

Anatomy of a Word Wrap

There are some good old articles here about word wrap routines, with some very fast and clever ones contributed by others (way better than mine). Check out those articles for better methods that what I am about to present.

Because I need to scan the line twice — one time to count the lines, and the second for the actual word wrap — I cannot mess with the user’s string. Instead, I’ll just use variables that sell me the Start Position (SP) within the string and End Position (EP) of the width-sized chunk I am going to scan. I’ll use a Position (P) variable and start at the end and scan backwards looking for a space. If I find one, I can count that as a line (increase the line count) and then move to the next character (to skip the space) and reset the Start Position to that. The process will repeat.

Since I do not want to duplicate code, I’ll embed the “print this section of the string” code in this routine, but use another variable to determine if I actually print it or now. I’m calling it Show (SH), and if SH=0 then it just counts, otherwise it prints as it counts each line.

It’s messy, but it works.

Here is a diagram showing the process:

When the space is located, it knows that from SP to that space position is something to print (a line).

Easy peasy.

Except it took me way too much brane power to figure this out, and I am sure it could be massively improved.

The routine will use the user’s width (W) variable to know how wide to make the box, and adjust the text space inside accordingly (W-2, leaving room for the borders).

The user can specify C for color, or if it’s not set (0) it will be assigned a color.

The starting location (S) must also be set. This is the top left of the pop-up box, in PRINT@ format (i.e. 0 is the top left of the screen, 32 is the start of the second line, etc.)

Here is what I came up with, along with a few lines at the start to test it out. It will keep displaying random sized pop-ups with the same text over and over and over. I used this to make sure it would work with the various size and color valuies.

NOTE: If you send in a width that is too narrow, it won’t work properly. Ideally I should check for that and have a minimum size. (I’ll try to add that in the final version, since I know it needs to be at least wide enough to fit “PRESS ANY KEY”.)

10 A$="THIS IS A LONG STRING THAT I WANT TO USE TO TEST WORD WRAPPING IN MY WINDOW ROUTINE."
20 W=RND(10)+20:S=48-W/2:C=RND(8)-1
30 CLS:GOSUB 1000
40 GOTO 20

999 END
1000 REM WINDOW SUBROUTINE 2.0
1001 REM  BY ALLEN C. HUFFMAN
1002 REM 8/8, 8/9/87 & 7/27/22
1993 REM    S-START W-IDTH
1004 REM    A$-TEXT C-COLOR
1005 REM
1010 IF C=0 THEN C=4
1020 SH=0:GOSUB 1120
1030 PRINT@S,CHR$(140)STRING$(W-2,140)CHR$(141);
1040 FOR A=1 TO LC+1
1050 PRINT@S+32*A,CHR$(133)STRING$(W-2,32)CHR$(133+16*C);
1060 NEXTA
1070 PRINT@S+32*(LC+1),CHR$(131)STRING$(W-2,131+16*C)CHR$(135+16*C);
1080 SH=1:GOSUB 1120
1090 PRINT@S+32*LC+W/2-7,"press"CHR$(128)"any"CHR$(128)"key";
1100 IF INKEY$="" THEN 1100 ELSE RETURN
1110 ' CALC LINE COUNT/PRINT
1120 LC=1:SP=1:LN=LEN(A$)
1130 EP=SP+W-2:P=EP
1140 IF EP>LN THEN 1190
1150 IF MID$(A$,P,1)<>" " THEN P=P-1 ELSE 1170
1160 IF P>SP THEN 1150 ELSE 1190
1170 IF SH<>0 THEN PRINT@S+32*LC+1,MID$(A$,SP,P-SP);
1180 LC=LC+1:SP=P+1:GOTO 1130
1190 IF SH<>0 THEN PRINT@S+32*LC+1,MID$(A$,SP);
1200 LC=LC+1:RETURN
1210 RETURN

One bad thing about this is all the variables I am using. And it could also be made faster by combining lines and such.

Here are some things I would like to do next:

• Check for a minimum width (if W<x then W=x).
• Combine lines to make it smaller and faster.
• Rename variables to all start with Z.

Z? Since my subroutine uses many variables, the calling program would have to make sure to not use any of them since the subroutine would change them. Today I like the approach of starting all my subroutine variables with Z, and just noting that “Zx variables are reserved for subroutines.” That way I can use any variables I want in my main program — other than the ones that are specifically used to pass values in to the subroutine — without worrying about a conflict.

I guess that means there will be a part 2. Until then, please comment with any ideas you have on improving this.

Until next time…

See Also: part 1, part 2, part 3, part 4 and part 5.

ASCII HEX data to maze graphics

As our spiraling trip down the rabbit hole continues, we finally return to drawing stuff instead of converting stuff.

We now have DATA statements that contain 2-byte hex numbers. Each hex number represents a byte (0-255) and each of those bytes represents 8 maze blocks on the screen.

For use in a Color BASIC program, we might want to take this HEX data and convert it in to string data (containing the final CHR$ values) for fast printing on the screen. If we were doing this in 6809 assembly, we might have the binary data contained in the executable, and convert it to a buffer that can then be copied to the screen as needed.

We’ll start with a simple (verbose) Color BASIC version. Since I am using the XRoar emulator to CLOAD this text file, I had to shorten the DATA lines a bit since they are now on higher lines, thus instead of loading “1DATA” it is loading “360DATA” taking up more bytes. I just moved some hex values to the next line.

I also adjusted my parser a bit. In my binary example, I wanted to handle binary numbers of any length. i.e, “111” would be 7, and “11111111” would be 255. To do this, I started with 0, and each time I saw a 1 I added one. For each new digit, I shifted the bits left by multiplying by 2. That way if it parsed “111” it would be “1 *2 +1 *2 +1” and so on for longer values.

For the maze, everything has to be a byte, so I took the opposite approach by starting with a bit value of 128 (representing the high bit in an 8-bit byte). Each time I found a new digit, I divided the bit value by 2 and either added it (if the new digit was a “1”, or “X” in the case of the maze) or not. That would make a maze of “XXXXXXXX” be “128 + 16 + 32 + 16 + 8 + 4 + 1” giving 255. If the maze data ran short, so the last few bytes were just “XXXX” it would be “128 + 64 + 32 + 16” which is &HF0 in hex (11110000), exactly what we want. If I had done it the other way, it would end up with 1111 (&H0F) and maze data would look like this:

GOOD:
-------- -------- ----
XXXXXXXX XXXXXXXX XXXX &HFF &HFF &HF0 -> 11111111 11111111 11110000

BAD:
-------- -------- ----
XXXXXXXX XXXXXXXX XXXX &HFF &HFF &H0F -> 11111111 11111111 00001111

I hope that makes sense. Anyway, here is the program I came up with… It will scan the hex values and build an array of strings (LN$) for each line. That way, the converted maze can be quickly printed after it has been generated once.

0 REM HEXMAZE.BAS
10 ' STRING SPACE IS MW*(MH+1)
20 CLEAR 28*32
30 ' SIZE OF MAZE IN DATA
40 MW=28:MH=31
50 ' ROOM FOR CONVERTED MAZE
60 DIM MZ$(MH):LN=0
70 CLS
80 ' READ A LINE OF HEX DATA
90 READ A$:IF A$="" THEN 340
100 ' EVERY 2 CHARS IS A HEX
110 FOR A=1 TO LEN(A$) STEP 2
120 ' COVERT HEX TO A VALUE
130 V=VAL("&H"+MID$(A$,A,2))
140 ' CONVERT BITS TO BLOCKS
150 BT=128
160 IF (V AND BT)=0 THEN B$=CHR$(128) ELSE B$=CHR$(175)
170 ' ADD BLOCK/SPACE TO STRING
180 MZ$(LN)=MZ$(LN)+B$
190 ' IF LEN >= MAZE W, NEXT
200 IF LEN(MZ$(LN))>=MW THEN 280
210 ' SHIFT BIT RIGHT
220 BT=INT(BT/2)
230 ' IF MORE BITS, REPEAT
240 IF BT>0 THEN 160
250 ' GET NEXT CHARACTER
260 GOTO 310
270 ' ELSE NEW MAZE LINE
280 PRINT MZ$(LN)
290 LN=LN+1
300 ' NEXT CHARACTER
310 NEXT
320 ' MORE LINES TO DO?
330 IF LN<MH THEN 90
340 END
350 REM MAZE AS HEX DATA
360 DATAFFFFFFF080060010BDF6FBD0BDF6FBD0BDF6FBD080000010BDBFDBD0BDBFDBD081861810FDF6FBF005F6FA0005801A0005BFDA00FDA05BF000204000FDA05BF005BFDA0005801A0005BFDA00FDBFDBF080060010BDF6FBD0BDF6FBD08C000310EDBFDB70EDBFDB7081861810BFF6FFD0BFF6FFD080000010
370 DATAFFFFFFF0,""

This program works, but it’s very slow, taking about 45 seconds to run. But, it’s verbose enough to (hopefully) explain what is going on.

By removing spaces, swapping out a integer values for faster HEX values, changing a CHR$() to a variable and adding a bit more string space, removing INT (and making one adjustment needed due to that), and combining lines, it can be sped up to just over 32 seconds.

0 REM HEXMAZE2.BAS
10 ' STRING SPACE IS MW*(MH+1)
20 CLEAR 28*32+200
30 ' SIZE OF MAZE IN DATA
40 MW=28:MH=31
50 ' ROOM FOR CONVERTED MAZE
60 DIM MZ$(MH):LN=0:BL$=CHR$(175)
70 CLS
90 READA$:IFA$=""THEN340
110 FORA=1TOLEN(A$)STEP2:V=VAL("&H"+MID$(A$,A,&H2)):BT=&H80
160 IF(V ANDBT)=0THENB$=BK$ELSEB$=BL$
180 MZ$(LN)=MZ$(LN)+B$:IFLEN(MZ$(LN))>=MW THEN280
220 BT=BT/2:IFBT>=1THEN160
260 GOTO310
280 PRINTMZ$(LN):LN=LN+1
310 NEXT:IFLN<MH THEN90
340 END
350 REM MAZE AS HEX DATA
360 DATAFFFFFFF080060010BDF6FBD0BDF6FBD0BDF6FBD080000010BDBFDBD0BDBFDBD081861810FDF6FBF005F6FA0005801A0005BFDA00FDA05BF000204000FDA05BF005BFDA0005801A0005BFDA00FDBFDBF080060010BDF6FBD0BDF6FBD08C000310EDBFDB70EDBFDB7081861810BFF6FFD0BFF6FFD080000010
370 DATAFFFFFFF0,""

And this is before translating that blocky maze into the “rounded corners” and such we want. This may be far too slow to do in BASIC since most folks don’t want to “Please wait 3.5 minutes while loading…” like a program my Commodore 64 friend once showed me. Assembly language helper routines might be needed for the impatient players out there…

Blocky to less blocky

After this code converts HEX values to maze data in a string array, we can process those strings and change the characters to have the “rounded” corners and such. Here is what I came up with, based on the original version that PEEKed and POKEed displayed bytes on the screen. This time, it’s scanning strings using MID$() and altering CHR$() values.

Side Note: Does everyone here know that, while you can’t use LEFT$ or RIGHT$ to change the left or right portion of a string, you can use MID$ to change characters? If you have A$=”1234567890″ and you want to change two characters starting at the third one, you can do MID$(A$,3,2)=”XX” and you get “12XX567890”. I’ll be using that…

Here is what I came up with… Instead of PEEKing memory, I used MID$(). It’s quite the mess, and very slow since I went back to the first version of the hex-to-maze print routine, just for clarity.

0 REM HEXMAZE3.BAS
10 ' STRING SPACE IS MW*(MH+1)
20 CLEAR 28*32
30 ' SIZE OF MAZE IN DATA
40 MW=28:MH=31
50 ' ROOM FOR CONVERTED MAZE
60 DIM MZ$(MH):LN=0
70 CLS
80 ' READ A LINE OF HEX DATA
90 READ A$:IF A$="" THEN 340
100 ' EVERY 2 CHARS IS A HEX
110 FOR A=1 TO LEN(A$) STEP 2
120 ' COVERT HEX TO A VALUE
130 V=VAL("&H"+MID$(A$,A,2))
140 ' CONVERT BITS TO BLOCKS
150 BT=128
160 IF (V AND BT)=0 THEN B$=CHR$(128) ELSE B$=CHR$(175)
170 ' ADD BLOCK/SPACE TO STRING
180 MZ$(LN)=MZ$(LN)+B$
190 ' IF LEN >= MAZE W, NEXT
200 IF LEN(MZ$(LN))>=MW THEN 280
210 ' SHIFT BIT RIGHT
220 BT=INT(BT/2)
230 ' IF MORE BITS, REPEAT
240 IF BT>0 THEN 160
250 ' GET NEXT CHARACTER
260 GOTO 310
270 ' ELSE NEW MAZE LINE
280 PRINT MZ$(LN)
290 LN=LN+1
300 ' NEXT CHARACTER
310 NEXT
320 ' MORE LINES TO DO?
330 IF LN<MH THEN 90

340 ' CONVERT LINES
350 BL$=CHR$(128):PRINT
360 FOR LN=0 TO MH-1
370 FOR C=1 TO LEN(MZ$(LN))
380 IF MID$(MZ$(LN),C,1)=BL$ THEN 510
390 V$=CHR$(175)
400 IF LN>0 THEN U$=MID$(MZ$(LN-1),C,1):UR$=MID$(MZ$(LN-1),C+1,1) ELSE U$=BL$:UR$=BL$
410 IF LN>0 THEN IF C>1 THEN UL$=MID$(MZ$(LN-1),C-1,1) ELSE ELSE UL$=BL$
420 IF C>1 THEN L$=MID$(MZ$(LN),C-1,1) ELSE L$=BL$
430 IF C<LEN(MZ$(LN)) THEN R$=MID$(MZ$(LN),C+1,1) ELSE R$=BL$
440 IF LN<MH-1 THEN D$=MID$(MZ$(LN+1),C,1) ELSE D$=BL$
450 IF LN<MH-1 THEN IF C>1 THEN DL$=MID$(MZ$(LN+1),C-1,1) ELSE ELSE DL$=BL$
460 IF LN<MH-1 THEN IF C<MW THEN DR$=MID$(MZ$(LN+1),C+1,1) ELSE ELSE DR$=BL$
470 IF U$<>BL$ THEN IF L$<>BL$ THEN GOSUB 600
480 IF U$<>BL$ THEN IF R$<>BL$ THEN GOSUB 700
490 IF D$<>BL$ THEN IF L$<>BL$ THEN GOSUB 800
500 IF D$<>BL$ THEN IF R$<>BL$ THEN GOSUB 900
510 NEXT:PRINT MZ$(LN):NEXT
520 END

600 ' UP and LEFT set
610 IF UL$<>BL$ THEN V$=CHR$(ASC(V$) AND NOT 8)
620 IF R$=BL$ THEN IF DR$=BL$ THEN IF D$=BL$ THEN V$=CHR$(ASC(V$) AND NOT 1)
630 MID$(MZ$(LN),C,1)=V$:RETURN

700 ' UP and RIGHT set
710 IF UR$<>BL$ THEN V$=CHR$(ASC(V$) AND NOT 4)
720 IF L$=BL$ THEN IF DL$=BL$ THEN IF D$=BL$ THEN V$=CHR$(ASC(V$) AND NOT 2)
730 MID$(MZ$(LN),C,1)=V$:RETURN

800 ' DOWN and LEFT set
810 IF DL$<>BL$ THEN V$=CHR$(ASC(V$) AND NOT 2)
820 IF U$=BL$ THEN IF UR$=BL$ THEN IF R$=BL$ THEN V$=CHR$(ASC(V$) AND NOT 4)
830 MID$(MZ$(LN),C,1)=V$:RETURN

900 ' DOWN and RIGHT set
910 IF DR$<>BL$ THEN V$=CHR$(ASC(V$) AND NOT 1)
920 IF L$=BL$ THEN IF UL$=BL$ THEN IF U$=BL$ THEN V$=CHR$(ASC(V$) AND NOT 8)
930 MID$(MZ$(LN),C,1)=V$:RETURN

1000 REM MAZE AS HEX DATA
1010 DATAFFFFFFF080060010BDF6FBD0BDF6FBD0BDF6FBD080000010BDBFDBD0BDBFDBD081861810FDF6FBF005F6FA0005801A0005BFDA00FDA05BF000204000FDA05BF005BFDA0005801A0005BFDA00FDBFDBF080060010BDF6FBD0BDF6FBD08C000310EDBFDB70EDBFDB7081861810BFF6FFD0BFF6FFD080000010
1020 DATAFFFFFFF0,""

Testing on the XRoar emulator shows this whole process takes about 161 seconds.

That’s so slow. Perhaps removing some of the CHR$() stuff and changing strings to values (like the originally PEEK version), skipping some of the extra IFs (like, if you are on line 0, there is no up, up left, or up right; if you are on the last line, there is no bottom, bottom left, or bottom right) and some other minor things might help…

340 ' CONVERT LINES
350 BL=128:PRINT
360 FOR LN=0 TO MH-1
365 LL=LEN(MZ$(LN))
370 FOR C=1 TO LL
380 IF ASC(MID$(MZ$(LN),C,1))=BL THEN 510
390 V=175

395 IF LN=0 THEN U=BL:UR=BL:UL=BL:GOTO 420
400 U=ASC(MID$(MZ$(LN-1),C,1)) ELSE U=BL
405 IF C<LL THEN UR=ASC(MID$(MZ$(LN-1),C+1,1)) ELSE UR=BL
410 IF C>1 THEN UL=ASC(MID$(MZ$(LN-1),C-1,1)) ELSE UL=BL

420 IF C>1 THEN L=ASC(MID$(MZ$(LN),C-1,1)) ELSE L=BL
430 IF C<LL THEN R=ASC(MID$(MZ$(LN),C+1,1)) ELSE R=BL

435 IF LN=MH-1 THEN D=BL:DL=BL:DR=BL:GOTO 470
440 D=ASC(MID$(MZ$(LN+1),C,1)) ELSE D=BL
450 IF C>1 THEN DL=ASC(MID$(MZ$(LN+1),C-1,1)) ELSE DL=BL
460 IF C<LL THEN DR=ASC(MID$(MZ$(LN+1),C+1,1)) ELSE DR=BL

470 IF U<>BL THEN IF L<>BL THEN GOSUB 600
480 IF U<>BL THEN IF R<>BL THEN GOSUB 700
490 IF D<>BL THEN IF L<>BL THEN GOSUB 800
500 IF D<>BL THEN IF R<>BL THEN GOSUB 900
510 NEXT:PRINT MZ$(LN):NEXT
515 PRINT TIMER,TIMER/60
520 END

600 ' UP and LEFT set
610 IF UL<>BL THEN V=(V AND NOT 8)
620 IF R=BL THEN IF DR=BL THEN IF D=BL THEN V=(V AND NOT 1)
630 MID$(MZ$(LN),C,1)=CHR$(V):RETURN

700 ' UP and RIGHT set
710 IF UR<>BL THEN V=(V AND NOT 4)
720 IF L=BL THEN IF DL=BL THEN IF D=BL THEN V=(V AND NOT 2)
730 MID$(MZ$(LN),C,1)=CHR$(V):RETURN

800 ' DOWN and LEFT set
810 IF DL<>BL THEN V=(V AND NOT 2)
820 IF U=BL THEN IF UR=BL THEN IF R=BL THEN V=(V AND NOT 4)
830 MID$(MZ$(LN),C,1)=CHR$(V):RETURN

900 ' DOWN and RIGHT set
910 IF DR<>BL THEN V=(V AND NOT 1)
920 IF L=BL THEN IF UL=BL THEN IF U=BL THEN V=(V AND NOT 8)
930 MID$(MZ$(LN),C,1)=CHR$(V):RETURN

Well, that brings it down to 155 seconds and that simply won’t do. There are many other optimizations to this BASIC program that could be done, and I bet we could even double the speed. But even then, that’s far too long to wait for a maze level to be drawn.

It looks like an assembly language routine might be our only option. We’ll take a break for now, but revisit this later after some discussion on assembly language. At some point. Eventually.

Until next time…