mirror of https://github.com/JorjBauer/aiie.git
updated docs
This commit is contained in:
Jorj Bauer
parent
81fb36789f
commit
69b794bc1d
96
README.md
96
README.md
|
|
@ -70,8 +70,8 @@ code, with the Teensy-specific code segregated as it is, I'm all ears...
|
|||
|
||||
I compile this with optimization set to "Faster" for the Teensy 3.6 at
|
||||
180MHz. There's no need to overclock the CPU -- but it does give
|
||||
better video performance, all the way up to 240MHz. Do as you see fit
|
||||
:)
|
||||
better video performance, all the way up to 240MHz, but still not
|
||||
perfect. Do as you see fit :)
|
||||
|
||||
Environment and Libraries
|
||||
-------------------------
|
||||
|
|
@ -100,13 +100,6 @@ eventually.
|
|||
|
||||
https://github.com/WMXZ-EU/uSDFS
|
||||
|
||||
### RingBuffer ###
|
||||
|
||||
My library for dealing with ring and circular buffers. Simplistic.
|
||||
You'll need v1.2.0 or later.
|
||||
|
||||
https://github.com/JorjBauer/RingBuffer
|
||||
|
||||
### RadioHead ###
|
||||
|
||||
This library comes with TeensyDuino, but I found the version that's
|
||||
|
|
@ -130,8 +123,14 @@ The reset/menu button brings up a BIOS menu:
|
|||
Debug: off
|
||||
Insert/Eject Disk 1
|
||||
Insert/Eject Disk 2
|
||||
Insert/Eject HD 1
|
||||
Insert/Eject HD 2
|
||||
Volume +
|
||||
Volume -
|
||||
Suspend
|
||||
Restore
|
||||
Prioritize Display/Audio
|
||||
|
||||
|
||||
Reset
|
||||
-----
|
||||
|
|
@ -195,7 +194,65 @@ This has several settings:
|
|||
Show time
|
||||
|
||||
... these are all fairly self-explanatory.
|
||||
|
||||
|
||||
Insert/Eject Disk1/2 HD1/2
|
||||
--------------------------
|
||||
|
||||
Fairly self-explanatory. Disks may be .dsk, .po, or .nib images
|
||||
(although .nib images aren't very heavily tested, particularly for
|
||||
write support). Hard drives are raw 32MB files, whose filenames must
|
||||
end in .img.
|
||||
|
||||
Suspend and Restore
|
||||
-------------------
|
||||
|
||||
The Teensy can be fully suspended and restored - including what disks
|
||||
are inserted. It's a full VM hibernation. It currently writes to a
|
||||
file named "suspend.vm" in the root of the MicroSD card. (I would like
|
||||
to be able to select from multiple suspend/restore files
|
||||
eventually. It wouldn't be terribly hard; it's just that the BIOS
|
||||
interface is very limited.)
|
||||
|
||||
Prioritize Display/Audio
|
||||
------------------------
|
||||
|
||||
Any Apple emulator needs real-time support for audio. The hardware is
|
||||
very direct: when a particular memory location ($C030) is read from or
|
||||
written to, the speaker's state is toggled. By doing this at specific
|
||||
times, the Apple generates a square wave - and this is the basis of
|
||||
the built-in audio. Obviously, then, the CPU has to be running at a
|
||||
specific frequency and the updates to the speaker have to come at
|
||||
exactly the right time.
|
||||
|
||||
The Mac version of AiiE runs the CPU a few cycles fast; and then while
|
||||
it's waiting for the CPU to catch up, it's slowly toggling the speaker
|
||||
at the right time. This works well because the actual computer it's
|
||||
running on is so much faster than the CPU it's emulating.
|
||||
|
||||
The Teensy verison can't afford all that overhead. It runs the virtual
|
||||
CPU in batches of 24-ish cycles, unless it updates the speaker; in
|
||||
which case, the virtual CPU returns control to the main program
|
||||
early. This was important while the Teensy code was queueing... but
|
||||
the queueing has since been removed, and its virtual MMU directly
|
||||
toggles the speaker as the virtual CPU is running. (This isn't quite
|
||||
as accurate as the Mac verison but it's close enough; uses less RAM;
|
||||
and uses less CPU.)
|
||||
|
||||
While all that's running, the display is also updating from the main
|
||||
loop. The trobule is that it takes quite a lot of time to update the
|
||||
display. Much longer than one CPU cycle. Much longer than hundreds of
|
||||
CPU cycles. Which means that one of two bad things happens.
|
||||
|
||||
Either (a) the CPU can run and update the video while you're still
|
||||
pushing that video to the screen - which means you can wind up with
|
||||
(e.g.) half a cloud in Skyfox at the top of the screen, and nothing
|
||||
immediately below it, because the video is "tearing" (getting partial
|
||||
results that change over time as it scans down the screen); or (b) you
|
||||
block the CPU from running while updating the display, which means the
|
||||
CPU runs in fits and starts. Since the audio is directly coupled to
|
||||
the CPU that also means the audio will be very messed up.
|
||||
|
||||
So this BIOS option lets you choose whether you want good audio or good video.
|
||||
|
||||
Building (on a Mac)
|
||||
===================
|
||||
|
|
@ -205,22 +262,17 @@ my first test target for most of the work. With MacOS 10.11.6 and
|
|||
Homebrew, you can build and run it like this:
|
||||
|
||||
<pre>
|
||||
$ make opencv
|
||||
$ ./aiie-opencv /path/to/disk.dsk
|
||||
$ make
|
||||
$ ./aiie-sdl /path/to/disk.dsk
|
||||
</pre>
|
||||
|
||||
As the name implies, this requires that OpenCV is installed and in
|
||||
As the name implies, this requires that SDL is installed and in
|
||||
/usr/local/lib. I've done that with Homebrew like this
|
||||
|
||||
<pre>
|
||||
$ brew install opencv
|
||||
$ brew install sdl2
|
||||
</pre>
|
||||
|
||||
"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).
|
||||
|
||||
Mockingboard
|
||||
============
|
||||
|
||||
|
|
@ -229,6 +281,12 @@ the Apple II Documentation Project:
|
|||
|
||||
https://mirrors.apple2.org.za/Apple%20II%20Documentation%20Project/Interface%20Cards/Audio/Sweet%20Microsystems%20Mockingboard/Schematics/Mockingboard%20Schematic.gif
|
||||
|
||||
I'm not sure the Teensy 3.6 has enough horsepower to run this, so I'm
|
||||
not sure it will ever come to be. It struggles to refresh the display
|
||||
and run the speaker at full tilt; but maybe that's primarily a
|
||||
function of the throughput to the display, and adding the Mockingboard
|
||||
support won't require further sacrifice...
|
||||
|
||||
VM
|
||||
==
|
||||
|
||||
|
|
|
|||
Loading…
Reference in New Issue