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286 lines
8.3 KiB
Markdown
286 lines
8.3 KiB
Markdown
Aiie!
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=====
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Aiie! is an Apple //e emulator, written ground-up for the Teensy
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3.6.
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The name comes from a game I used to play on the Apple //e back
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around 1986 - Ali Baba and the Forty Thieves, published by Quality
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Software in 1981.
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http://crpgaddict.blogspot.com/2013/07/game-103-ali-baba-and-forty-thieves-1981.html
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When characters in the game did damage to each other, they exclaimed
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something like "HAH! JUST A SCRATCH!" or "AAARGH!" or "OH MA, I THINK
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ITS MY TIME" [sic]. One of these exclamations was "AIIYEEEEE!!"
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Build log:
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----------
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https://hackaday.io/project/19925-aiie-an-embedded-apple-e-emulator
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Getting the ROMs
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================
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As with many emulators, you have to go get the ROMs yourself. I've got
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the ROMs that I dumped out of my Apple //e. You can probably get yours
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a lot easier.
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There are three files that you'll need:
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* apple2e.rom -- a 32k dump of the entire Apple //e ROM
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* disk.rom -- a 256 byte dump of the DiskII controller ROM (16-sector P5)
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* parallel.rom -- a 256 byte dump of the Apple Parallel Card
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The MD5 sums of those files are:
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* 003a780b461c96ae3e72861ed0f4d3d9 apple2e.rom
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* 2020aa1413ff77fe29353f3ee72dc295 disk.rom
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* 5902996f16dc78fc013f6e1db14805b3 parallel.rom
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From those, the appropriate headers will be automatically generated by
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"make roms" (or any other target that relies on the ROMs).
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Building (for the Teensy)
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=========================
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The directory 'teensy' contains 'teensy.ino' - the Arduino development
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environment project file. You'll need to open that up and compile from
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within.
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However.
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I built this on a Mac, and I used a lot of symlinks because of
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limitations in the Arduino IDE. There's no reason that shouldn't work
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under Linux, but I have absolutely no idea what Windows will make of
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it. I would expect trouble. No, I won't accept pull requests that
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remove the symlinks and replace them with the bare files. Sorry.
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Also, you'll have to build the ROM headers (above) with 'make roms'
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before you can build the Teensy .ino file.
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If anyone knows how to make the Arduino development environment do any
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form of scripting that could be used to generate those headers, I'd
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gladly adopt that instead of forcing folks to run the Perl script via
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Makefile. And if you have a better way of dealing with subfolders of
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code, with the Teensy-specific code segregated as it is, I'm all ears...
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I compile this with optimization set to "Faster" for the Teensy 3.6 at
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180MHz. There's no need to overclock the CPU -- but it does give
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better video performance, all the way up to 240MHz. Do as you see fit
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:)
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Environment and Libraries
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-------------------------
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I built this with arduino 1.8.1 and TeensyDuino 1.35.
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https://www.pjrc.com/teensy/td_download.html
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These libraries I'm using right from Teensy's environment: TimerOne;
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SPI; EEPROM; Time; Keypad.
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There's an error in the Time library. On Macs, where the filesystem is
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case-insensitive, you'll have to do something like this:
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<pre>
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$ mv /Applications/Arduino.app/Contents/Java//hardware/teensy/avr/libraries/Time/Time.h /Applications/Arduino.app/Contents/Java//hardware/teensy/avr/libraries/Time/_Time.h
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</pre>
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I'm also using these libraries that don't come with TeensyDuino:
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### uSDFS ###
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This has long filename support, where the Teensy SD library
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doesn't. It's pretty messy code, though, and I hope to abandon it
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eventually.
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https://github.com/WMXZ-EU/uSDFS
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### RingBuffer ###
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My library for dealing with ring and circular buffers. Simplistic.
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You'll need v1.2.0 or later.
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https://github.com/JorjBauer/RingBuffer
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### RadioHead ###
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This library comes with TeensyDuino, but I found the version that's
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with 1.35 hangs. Using the stock v1.70 seems to be fine.
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http://www.airspayce.com/mikem/arduino/RadioHead
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Running (on the Teensy)
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=======================
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The reset/menu button brings up a BIOS menu:
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Resume
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Reset
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Cold Reboot
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Drop to Monitor
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Display: RGB
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Debug: off
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Insert/Eject Disk 1
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Insert/Eject Disk 2
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Volume +
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Volume -
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Reset
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-----
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This is the same as control-reset on the actual hardware. If you
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want to execute the Apple //e self-test, then hold down the two
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joystick buttons; hit the reset/menu key; and select "Reset".
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Cold Reboot
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-----------
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This resets much of the hardware to a default state and forces a
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reboot. (You can get the self-test using this, too.)
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Drop to Monitor
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---------------
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"Drop to Monitor" tries fairly hard to get you back to a monitor
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prompt. Useful for debugging, probably not for much else.
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Display
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-------
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"Display" has four values, and they're only really implemented for
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text and hi-res modes (not for lo-res modes). To describe them, I have
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to talk about the details of the Apple II display system.
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In hires modes, the Apple II can only display certain colors in
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certain horizontal pixel columns. Because of how the composite video
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out works, the color "carries over" from one pixel to its neighbor;
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multiple pixels turned on in a row makes them all white. Which means
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that, if you're trying to display a picture in hires mode, you get
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color artifacts on the edges of white areas.
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The Apple Color Composite Monitor had a button on it that turned on
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"Monochrome" mode, with the finer resolution necessary to display the
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pixels without the color cast. So its two display modes would be the
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ones I call "NTSC-like" and "Black and White."
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There are two other video modes. The "RGB" mode (the default, because
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it's my preference) shows the color pixels as they're actually drawn
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in to memory. That means there can't be a solid field of, for example,
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orange; there can only be vertical stripes of orange with black
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between them.
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The last mode is "Monochrome" which looks like the original "Monitor
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II", a black-and-green display.
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Debug
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-----
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This has several settings:
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off
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Show FPS
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Show mem free
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Show paddles
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Show PC
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Show cycles
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Show battery
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Show time
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... these are all fairly self-explanatory.
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Building (on a Mac)
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===================
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While this isn't the purpose of the emulator, it is functional, and is
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my first test target for most of the work. With MacOS 10.11.6 and
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Homebrew, you can build and run it like this:
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<pre>
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$ make opencv
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$ ./aiie-opencv /path/to/disk.dsk
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</pre>
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As the name implies, this requires that OpenCV is installed and in
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/usr/local/lib. I've done that with Homebrew like this
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<pre>
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$ brew install opencv
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</pre>
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"Why OpenCV?" you might ask. Well, it's just because I had code from
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another project lying around that directly manipulated OpenCV bitmap
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data. It's functional, and the Mac build is only about functional
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testing (for me).
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VM
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==
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The virtual machine architecture is broken in half - the virtual and
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physical pieces. There's the root VM object (vm.h), which ties
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together the MMU, virtual keyboard, and virtual display.
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Then there are the physical interfaces, which aren't as well
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organized. They exist as globals in globals.cpp:
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<pre>
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FileManager *g_filemanager = NULL;
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PhysicalDisplay *g_display = NULL;
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PhysicalKeyboard *g_keyboard = NULL;
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PhysicalSpeaker *g_speaker = NULL;
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PhysicalPaddles *g_paddles = NULL;
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</pre>
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There are the two globals that point to the VM and the virtual CPU:
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<pre>
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Cpu *g_cpu = NULL;
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VM *g_vm = NULL;
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</pre>
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And there are two global configuration values that probably belong in
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some sort of Prefs class:
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<pre>
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int16_t g_volume;
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uint8_t g_displayType;
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</pre>
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CPU
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===
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The CPU is a 65C02, not quite complete; it supports all of the 65C02
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documented opcodes but not the undocumented ones here:
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http://www.oxyron.de/html/opcodes02.html
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The timing of the CPU is also not quite correct. It's close, but
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doesn't count cycles due to page boundary crossings during branch
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instructions. (See the "cycle count footnotes" in cpu.cpp.)
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The CPU passes the 6502 functional test from here:
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https://github.com/Klaus2m5/6502_65C02_functional_tests
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... which is included in binary form in the test harness (see the .h
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files in util/ for notes).
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testharness.basic should reach "test number 240", hang for a while,
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and then exit.
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testharness.verbose should show that it gets through 43 tests, test
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240, and then loops repeatedly for a while (exiting at a somewhat
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arbitrary point).
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testharness.extended currently fails (hanging at 0x733) because I
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haven't implemented the undocumented opcodes. It should get to address
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0x24a8 and hang. Some day I'll finish implementing all of the
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undocumented opcodes :)
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