3.6 KiB
Aiie!
Aiie! is an Apple //e emulator, written ground-up for the Teensy 3.6.
The name comes from a game I used to play on the Apple //e back around 1986 - Ali Baba and the Forty Thieves, published by Quality Software in 1981.
http://crpgaddict.blogspot.com/2013/07/game-103-ali-baba-and-forty-thieves-1981.html
When characters in the game did damage to each other, they exclaimed something like "HAH! JUST A SCRATCH!" or "AAARGH!" or "OH MA, I THINK ITS MY TIME" [sic]. One of these exclamations was "AIIYEEEEE!!"
Build log:
https://hackaday.io/project/19925-aiie-an-embedded-apple-e-emulator
Getting the ROMs
As with many emulators, you have to go get the ROMs yourself. I've got the ROMs that I dumped out of my Apple //e. You can probably get yours a lot easier.
There are two files that you'll need:
apple2e.rom -- a 32k dump of the entire Apple //e ROM disk.rom -- a 256 byte dump of the DiskII controller ROM (16-sector P5)
The MD5 sums of those two files are:
003a780b461c96ae3e72861ed0f4d3d9 apple2e.rom 2020aa1413ff77fe29353f3ee72dc295 disk.rom
From those, the appropriate headers will be automatically generated by "make roms" (or any other target that relies on the ROMs).
Building (on a Mac)
While this isn't the purpose of the emulator, it is functional, and is my first test target for most of the work. With MacOS 10.11.6 and Homebrew, you can build and run it like this:
$ make opencv $ ./aiie-opencv /path/to/disk.dsk
As the name implies, this requires that OpenCV is installed and in /usr/local/lib. I've done that with Homebrew like this
$ brew install opencv
"Why OpenCV?" you might ask. Well, it's just because I had code from another project lying around that directly manipulated OpenCV bitmap data. It's functional, and the Mac build is only about functional testing (for me).
VM
The virtual machine architecture is broken in half - the virtual and physical pieces. There's the root VM object (vm.h), which ties together the MMU, virtual keyboard, and virtual display.
Then there are the physical interfaces, which aren't as well organized. They exist as globals in globals.cpp:
FileManager *g_filemanager = NULL;
PhysicalDisplay *g_display = NULL;
PhysicalKeyboard *g_keyboard = NULL;
PhysicalSpeaker *g_speaker = NULL;
PhysicalPaddles *g_paddles = NULL;
There are the two globals that point to the VM and the virtual CPU:
Cpu *g_cpu = NULL;
VM *g_vm = NULL;
And there are two global configuration values that probably belong in some sort of Prefs class:
int16_t g_volume;
uint8_t g_displayType;
CPU
The CPU is a 65C02, not quite complete; it supports all of the 65C02 documented opcodes but not the undocumented ones here:
http://www.oxyron.de/html/opcodes02.html
The timing of the CPU is also not quite correct. It's close, but doesn't count cycles due to page boundary crossings during branch instructions. (See the "cycle count footnotes" in cpu.cpp.)
The CPU passes the 6502 functional test from here:
https://github.com/Klaus2m5/6502_65C02_functional_tests
... which is included in binary form in the test harness (see the .h files in util/ for notes).
testharness.basic should reach "test number 240", hang for a while, and then exit.
testharness.verbose should show that it gets through 43 tests, test 240, and then loops repeatedly for a while (exiting at a somewhat arbitrary point).
testharness.extended currently fails (hanging at 0x733) because I haven't implemented the undocumented opcodes. It should get to address 0x24a8 and hang. Some day I'll finish implementing all of the undocumented opcodes :)