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And there it is: a Device Manager Error when you quit the application. There is some housekeeping in the Device Manager that is not getting done correctly after the contents of the I/O queue are tampered with directly. Fortunately there are toolbox routines for managing this queue. MacKaboom’s...

MacKaboom’s sound framework uses KillIO before every sound so the Device Manager can stop whatever is playing in order to play what’s next. Without it, sounds cannot interrupt sounds. Instead, they pile up in the Device Manager’s I/O queue and wait their turn to be played. What if... instead of...

I got some assembly tips from the maker of Advanced Mac Substitute and tried one with John Stogdell Stokes III’s M68000 Condition Code Demonstrator, a terrific Desk Accessory that lets you evaluate M68k operations. A later version (1.3) is on Macintosh Garden. The demonstration below and shows...

Thanks for the link, @Snial. Funny to see Apple’s own PR describing it as an “embarrassing click.” Poor Andy Hertzfeld, who was forced to write the Sound Driver in one weekend, getting thrown under the bus like this! I would love to use the Sound Manager, but it is not supported on the 128k and...

Tonight I spent some time with MAME’s debugging tools to figure out why I was getting an address error on 64k ROM machines like the 128k and Fat Mac. Turns out it was happening in the MaxApplZone trap. It might be incompatible with the alternate video buffer on the 64k ROM. The 128k ROM has no...

There appear to be two culprits behind that first popping sound: When your Mac starts, the sound buffer is entirely full with one of the loudest bytes you can put into it: $FF The first time the Mac makes a sound, it turns on the amplifier, which makes it pop a little. Just changing the volume...

Thanks very much, @Crutch!

Games on the Mac need their sounds prepared properly so they are ready to play and padded to the correct byte length, otherwise they might play during floppy access (which garbles them) or make an awful popping sound because their length is not an even multiple of the sound buffer’s size. Since...

This is really going to hurt sales. ; ----------------------------------------------------------------------------- ; Check that screen resolution is 512×342 RESOLUTION_CHECK MOVE.L (A5),A0 ; A0 = QuickDraw vars LEA...

It’s actually a 4MB Mac Plus in disguise, but it was an original 128k when I first got it in 1985! MacASM is pretty nifty for what it manages to do with such a small footprint. I contemplated using it for my project, but adopted MDS because all of the assembly books I’ve been reading use it in...

Good guess! That would make a great desk accessory. Winner!

Switching to the alternate video buffer (and back to the main one) is just a matter of flipping a bit. ; ----------------------------------------------------------------------------- ; Toggle between the main and alternate video buffers FLIP_SCREEN MOVE.L CurrScrn(A5),A0...

One of the first things I did was figure out how to enable the alternate video buffer. This was an early feature Apple provided so developers could instantly flip the Mac’s video circuitry to show bitmaps from a different memory address. Inside Macintosh Vol. 1 suggests its use to obtain...

I started tinkering on this a month ago and thought I would start sharing my progress about it here on 68kMLA. Why assembly? Good question. The short answer: it’s just a self-imposed challenge. The long answer: I grew up using a Mac Plus, which gave me the skills that led to an enjoyable career...

I have not found the code that went with Dan Weston’s books, but MDS comes with a couple of beginner programs to get you started. I recommend “Sample.asm” on the second disk of MDS 2.0. It shows how to do a variety of common GUI tasks with the Toolbox, and every line of code is annotated with...

@Crutch It was an eBay find from March 2019, almost four years ago. The seller was asking $150, but took an offer for $90. I was briefly infatuated with MacASM because of its unified editing and execution environment, but its kooky keyboard-centric interface proved to be too frustrating. All...

I bought a physical copy of Vol. 1 last summer so I could read it on vacation. Dan’s practical examples really helped me get started with my own project. Stack frames with LINK would still be an inexplicable mystery to me without his 13-page tutorial. MDS is a delightful sandbox to play in...

Damn my middle-aged reading comprehension; somehow I missed your last sentence about “the staple-bound v2.0 manual supplement”. How long is it? Is it something you can scan and share?

Did you find out what the “Toolbox Interface Reference Package” is? I wonder if it has assembly-centric documentation for all the Toolbox routines. Inside Macintosh’s documentation is largely Pascal-centric and it often leaves me wondering, “does the argument for this routine go into D0? Or does...

Just for the heck of it, try reading the tick count from the memory location ($16A) where the vertical retrace manager keeps it. Do you have the same bouncing around problem?