This is pretty neat. I have been spending the past few months adding an ARM64 JIT to Basilisk II (https://github.com/rcarmo/macemu) and totally appreciate what's involved (I'm currently stuck patching a Quadra ROM to bypass NuBus hardware detection...)
Will definitely give it a try, since I would _love_ to have a Classic Mac environment with some modern creature comforts (like file sharing) in tiny machines.
I am amazed that 1980's software works on binary API compatibility rather than relying on API quirks like timing, memory alignment quirks, memory layout from specific allocator behaviour, etc.
It only takes one unintentional reliance on an implementation detail to make an application not run on another OS implementation...
The Mac classic was about as pure as you could get from an architectural point of view.
A 1 bit framebuffer and a CPU gets you most of what the machine can do.
Most of the quirk abuse of 8-bit machines came from features that were provided with limitations. Sprites, but only 8 of them, colours but only 2 in any 8x8 cell. Multicolour but only in one of two palettes and you'll hate both.
Almost all of the hacks were to get around the limitations of the features.
I don't know if the decision apple made was specifically with future machines in mind. It certainly would have been a headache to make new machines 5 generations down the track if the first one had player missile graphics.
They mostly relied on OS/Toolbox implementation quirks though, not hardware implementation quirks, because applications that relied on the latter wouldn’t run on the Macintosh XL and that mattered to certain market segments. (Like some people using spreadsheets, who were willing to trade CPU speed for screen size.) Similarly anything that tried to use floppy copy protection tricks wouldn’t work due to the different system design, so that wasn’t common among applications.
So even things that wrote directly to the framebuffer would ask the OS for the address and bounds rather than hardcode them, copy protection would be implemented using license keys (crypto/hashes, not dongles) rather than weird track layouts on floppies, etc. It led to good enough forward compatibility that the substantial architectural changes in the Macintosh II were possible, and things just improved from there.
Eh, there were plenty of games that were coded for a particular clock speed, and then once the SE came out, had an update that included a software version of a turbo button, let you select which of two speeds to run at. They run FAST on an SE/30 or Mac II and unusably fast on anything newer.
I didn’t encounter too many of those back in the day, I think because there was the VBL task mechanism for synchronizing with screen refresh that made it easy to avoid using instruction loops for timing.
Much more common in my experience was the assumption that the framebuffer was 1-bit, but such games would still run on my IIci if I switched to black & white—they’d just use the upper left 3/4 of the screen since they still paid proper attention to the bytes-per-row in its GrafPort.
Could be that by the time I was using a Mac II though that all the games that didn’t meet that minimum bar had already been weeded out.
Out of curiosity, what app are you thinking of? Of all of types of software used with classic Mac OS (INITs, CDEVs, FKEYs, Desk Accessories, Drivers, etc.), apps would be the least likely to rely on implemention quirks.
I can't imagine how fast this is compared to the original hardware that ran it. I remember using a Mac 512k with a single floppy drive (no hard drive support) and doing the insert-floppy-dance. Computers were far more mechanical then.
It would be fun to have a "slow it down" feature that also has the various floppy read/write noises paired with it. Bonus points for different generations of hardware and having the OG HD noises to pair with those too!
"Fond" memories of playing King's Quest IV as a little kid on my parents' Apple IIe. You had to swap in a new 5.25" floppy almost every time you walked to another screen. I was fascinated by the game but my god was it tedious to constantly flip and swap the disks around. Google says it came on 8 double sided disks, I could have sworn it was a couple dozen.
The game I played for hours on the Apple ][+ was "FantasyLand 2041". It came on six double sided disks, and I was bummed to find out after quite a lot of game time that disk six was corrupted. I then found out many years later that it wasn't corrupted, the game wasn't ever finished. I then further discovered that John Bell, who produced that and other popular games (Sand of Mars, Beneath the Pyramids, House of Usher), is utterly batty and has written a few "the government is hiding UFOs from us" books.
There was a show HN retro HW project somewhat recently that included sound emulation on board. Maybe that author is reading this, but their sound emulation was probably my favorite part (not to disregard the actual hard parts! I just found it charming)
I'd like to see something like Carbon for old apps so that they boot in modern window frames (without the missing Tahoe corners) and can save to files.
This triggered flashbacks. I'm not sure if I'm remembering correctly, but I think we sometimes also used used Pascal, and it was optional for some toolboxes. It's been a long time though so I could be mistaken. That might have been pre-Mac? But good times, though. Boy, is the world a different place.
The original Mac system software was written in Pascal and most Mac toolbox calls took Pascal-style (prefixed by length) rather than C-style (terminated with null character) strings. But you could write application code in either language keeping this caveat in mind.
It was actually mostly written in assembly, but used Pascal calling conventions and structure layouts since that was expected to be the primary language for application developers. As it had been for Lisa, as it was for “large” applications on Apple II, and as was the case for much of the rest of the microcomputer and minicomputer industry and even the nascent workstation industry (eg Apollo).
It was the Lisa system software that was mostly implemented in Pascal and some blamed this for its largeness and its performance. Compilers and linkers weren’t great back then; most compiler code generation was pretty rigid, and most linkers didn’t even coalesce identical string literals across compilation unit boundaries!
Lisa Workshop C introduced the “pascal” keyword for function declarations and definitions to indicate they used Pascal calling conventions, and otherwise followed Lisa Pascal structure layout rules, so as to minimize the overhead of interoperating with the OS. (I’m not sure whether it introduced the “\p” Pascal string literal convention too or if that came later with Stanford or THINK Lightspeed C.)
I'm guessing they reimplemented the toolbox at the TRAP level (most MacOS calls at the time were accessed through the 68K TRAP instruction).
So, rather than emulating hardware to run native ROMs, they "simply" reimplemented the ROMs.
A friend of mine did this at another level. He basically rewrote the bulk of the toolbox as a C library so that the company, who had a Mac application, could port it to run on a PC, while sharing the source code.
This was before Windows, and it worked! Launched it from DOS, takes over the entire screen. He didn't copy the Mac look and feel. Instead he used OpenLook for his gadgets and what not (since it was, you know, "open").
But he rewrote the bulk of it: QuickDraw, Event Manager, Memory Manager, Window Manager, etc. Just ate it like an elephant. I don't think his regions were as clever as the Mac. Pretty sure he just stuck with rectangles.
Correction: 68K Mac OS calls were A-line traps — in other words, they had opcodes of the form `$Axxx`. To the processor, they're unimplemented instructions that each take an exception through the same vector. The exception handler is the Mac OS trap dispatcher.
`TRAP` is a different instruction, with opcodes `$4E4x`. Each one gets its own exception vector.
It's not just trap calls, though — sometimes applications write directly to the sound buffer or use hardware page flipping.
Hm, doesn't seem to work. Let's try the X11 version:
make ams-x11
./build.pl -i exhibit graft skif minivx xv68k freemountd interact-x11
...
T=0.275s ERROR: OpenDF is unimplemented
Nope, it seems to be missing something. OpenDF? All I find is this: https://github.com/PrjEnt/OpenDF, a long-abandoned project which seems to be a more compact version of another abandoned thing.
The FSSpec calls added in System 7 are mostly new interfaces to existing File Manager functionality. There's an actual high-level `OpenDF()` call, which is like `FSOpen()` except that it won't try to open a driver when the name begins with `.`.
Some applications call `OpenDF()` without checking its availability, but fall back to `FSOpen()` or equivalent if `OpenDF()` returns `paramErr`, which is what the parent is witnessing. See `68k/modules/ams-fs/Files.cc` in the `metamage_1` repo.
If the error message is confusing people, maybe it's time to implement `OpenDF()` for real.
Strange it errors out on given that I assume the thing does run elsewhere. The X11 version sometimes shows the opening screen but any attempt at interaction leads to the mentioned error. The VLC version shows the error directly.
Yes, that works, the tic-tac-toe thing appears and remains even though the error message regarding OpenDF is shown. In other words that error message can be ignored, at least as long as whatever is in AMS_APPNAME does not require whatever OpenDF provides.
Will definitely give it a try, since I would _love_ to have a Classic Mac environment with some modern creature comforts (like file sharing) in tiny machines.
It only takes one unintentional reliance on an implementation detail to make an application not run on another OS implementation...
A 1 bit framebuffer and a CPU gets you most of what the machine can do.
Most of the quirk abuse of 8-bit machines came from features that were provided with limitations. Sprites, but only 8 of them, colours but only 2 in any 8x8 cell. Multicolour but only in one of two palettes and you'll hate both.
Almost all of the hacks were to get around the limitations of the features.
I don't know if the decision apple made was specifically with future machines in mind. It certainly would have been a headache to make new machines 5 generations down the track if the first one had player missile graphics.
So even things that wrote directly to the framebuffer would ask the OS for the address and bounds rather than hardcode them, copy protection would be implemented using license keys (crypto/hashes, not dongles) rather than weird track layouts on floppies, etc. It led to good enough forward compatibility that the substantial architectural changes in the Macintosh II were possible, and things just improved from there.
Much more common in my experience was the assumption that the framebuffer was 1-bit, but such games would still run on my IIci if I switched to black & white—they’d just use the upper left 3/4 of the screen since they still paid proper attention to the bytes-per-row in its GrafPort.
Could be that by the time I was using a Mac II though that all the games that didn’t meet that minimum bar had already been weeded out.
It would be fun to have a "slow it down" feature that also has the various floppy read/write noises paired with it. Bonus points for different generations of hardware and having the OG HD noises to pair with those too!
For example, check out the MacPaint demo:
https://www.v68k.org/advanced-mac-substitute/demo/MacPaint-A...
If you were to double-click the Hello document in macOS' Finder, it would launch and open in MacPaint.app.
Many hours were wasted on that game.
and yes:
https://github.com/jjuran/metamage_1/commit/30cb0e260d5ff478...
It was the Lisa system software that was mostly implemented in Pascal and some blamed this for its largeness and its performance. Compilers and linkers weren’t great back then; most compiler code generation was pretty rigid, and most linkers didn’t even coalesce identical string literals across compilation unit boundaries!
Lisa Workshop C introduced the “pascal” keyword for function declarations and definitions to indicate they used Pascal calling conventions, and otherwise followed Lisa Pascal structure layout rules, so as to minimize the overhead of interoperating with the OS. (I’m not sure whether it introduced the “\p” Pascal string literal convention too or if that came later with Stanford or THINK Lightspeed C.)
So, rather than emulating hardware to run native ROMs, they "simply" reimplemented the ROMs.
A friend of mine did this at another level. He basically rewrote the bulk of the toolbox as a C library so that the company, who had a Mac application, could port it to run on a PC, while sharing the source code.
This was before Windows, and it worked! Launched it from DOS, takes over the entire screen. He didn't copy the Mac look and feel. Instead he used OpenLook for his gadgets and what not (since it was, you know, "open").
But he rewrote the bulk of it: QuickDraw, Event Manager, Memory Manager, Window Manager, etc. Just ate it like an elephant. I don't think his regions were as clever as the Mac. Pretty sure he just stuck with rectangles.
`TRAP` is a different instruction, with opcodes `$4E4x`. Each one gets its own exception vector.
It's not just trap calls, though — sometimes applications write directly to the sound buffer or use hardware page flipping.
Some applications call `OpenDF()` without checking its availability, but fall back to `FSOpen()` or equivalent if `OpenDF()` returns `paramErr`, which is what the parent is witnessing. See `68k/modules/ams-fs/Files.cc` in the `metamage_1` repo.
If the error message is confusing people, maybe it's time to implement `OpenDF()` for real.
You clipped the part that said "Starting VNC server on 127.0.0.1:5900". Did you try connecting a VNC client?