Epple ][

The slot command inserts a card into a peripheral slot of the emulated Apple.

<slot> Slot number, 0 through 7, to insert the card into.

<card> The type of card to insert into the slot:

The slot command inserts a card into a peripheral slot. For example:

inserts a language card into slot zero. Use empty to remove a card:

The import command imports a binary image file into the emulated Apple’s memory.

<slot> Slot number, 0 through 7, of peripheral card to import the binary image into.

<base> Base address in hexadecimal within the given memory area at which to start loading the binary image.

<file-path> Path of the binary image to import.

The import command reads the binary image byte-for-byte from the given file-path into an area of memory in the emulated Apple. You can load into either the motherboard or a card in one of the slots. For the motherboard, you choose the RAM or ROM area. For a card in a slot, you can choose either the normal ROM, the bank-switched ROM, or the so-called “seventh ROM” area.

You also have to specify the base address within the specific memory area at which the image file will be loaded. Note that the base address is specified as the offset within the specific memory area, and not necessarily as the actual memory address as seen by the Apple. So for motherboard ROM, for example, specifying a base as 2DED will cause the image to be loaded at offset 2DED in the ROM, which will be addressed by the Apple at memory address $FDED (because motherboard ROM “starts” at address $D000).

For peripheral cards, the ROM will be seen at locations $Cs00-$CsFF, where s is the slot number (1 through 7). The “seventh ROM” can be seen as locations $C800-$CFFF; Jim Sather describes this functionality in Understanding the Apple II, on page 6-4, section “The Seventh ROM Chip.” The EPPLE ][ emulator handles this processing correctly. A card can also have bank-switched ROM, which will show up at addresses $D000-$FFFF when switched in (stealing that address range from motherboard ROM… see Understanding the Apple II, p. 5-26 “The 16K RAM Card”).

The load command loads a (nibble) floppy disk image into one of the emulated disk drives.

<slot> Slot number, 0 through 7, of Disk ][ controller card to load the nibble image into.

<drive> Drive number, 1 or 2, of the disk drive on the controller card to load the nibble image into.

<file-path> Path of the nibble floppy disk image to import.

The load command will load a nibble image into a disk drive. Specify the slot that contains a Disk ][ controller peripheral card, and specify which drive number (1 or 2).

The best floppy disk image conversion tool I’ve found is CiderPress, for Windows (but it supposedly runs under Wine on Linux, too). Thanks to Andy McFadden.

The unload command removes a floppy disk image from one of the emulated disk drives.

<slot> Slot number, 0 through 7, of Disk ][ controller card to which the drive is attached.

<drive> Drive number, 1 or 2, of the disk drive on the controller card to remove the floppy disk image from.

The unload command removes the disk from the specified slot and drive.

The save command saves changes made on an emulated floppy disk back to the original image file.

<slot> Slot number, 0 through 7, of Disk ][ controller card to which the drive is attached.

<drive> Drive number, 1 or 2, of the disk drive on the controller card to save.

<file-path> Path of the nibble floppy disk image to import.

The save command saves any changes that the emulated Apple ][ has made to the floppy disk image. It is important to note that the emulator operates on the image only in memory, and does not immediately write changes back to the real file. You need to issue the save command in order to write changes back to the file. Note that the emulator will display a asterisk * next to the file-name of a disk image if it has any unsaved changes.

The cassette command performs various operations of the emulated cassette tape.

<file-path> File path of the (special format) cassette tape image file.

The cassette command allows the user to control the emulated cassette tape player. See Cassette for more information about operating the emulated cassette player and cassette tape image files.

The revision command specifies which revision of Apple ][ motherboard to use.

<rev> Revision number of the motherboard. Currently, only two values make any difference in behavior: 0 or 1.

The revision command chooses which revision of the Apple ][ motherboard to use. The only revisions that make any difference (for now, at least) are 0 or 1. Zero is the original (now quite rare) version of the motherboard, that only had two hi-res colors (green and purple), and always displayed text with green and purple fringes. Revision 1 and later motherboards are the ones we are more familiar with.

The emulator provides a color monitor, and three monochrome monitors (white, green, and orange). These emulate standard, no-frills NTSC monitors. The most noticeable characteristic of monitors is the horizontal display of pixels. Monitors react faster than TVs, so two adjacent pixels will not merge together; both will be distinctly visible, with blackness between them. For example, type in the following Applesoft command, then cycle through the display types. The monitors will show thin, vertical, green lines; TVs will show continuous horizontal lines.

There are two types of television displays, referred to as “old” and “new.” Each has color and monochrome (commonly known as “black and white”) varieties. Televisions react more slowly to changes in the incoming video signal than monitors do, and as a result, horizontal pixels will merge together, forming a more uniform appearance. The “new” color TV display uses the pre-defined color pallette (described below under “Colors”), and the black and white TV uses the same pallette, but fully desaturated. The “old” color TV is the most interesting. It emulates the signal decoding circuitry of a real television. This includes separating out the “chroma” portion of the incoming NTSC video signal using a filter algorithm, and calculating the color to display. It does not use the pre-defined colors.

The color palatte used for the color monitor and new color TV is pre-defined, and was determined through observation of a real Apple ][ machine on a standard TV, the colors being matched by eye. The old color TV, however, uses algorithms to calculate the colors it displays.

NTSC displays (TVs or monitors) usually receive signals that are interlaced. However, the Apple ][ doesn’t generate interlaced screens. This causes blank rows between each displayed row of pixels. The EPPLE ][ emulates this behavior, but also allows you to “fill in” these black rows with a copy of the row above it, for a more continuous display (vertically). Use the F4 key to toggle between these two modes.

The Apple ][s are commonly documented as having a resolution of 280x192 pixels, and to an extent this is true. Vertically there are 192 pixels, but since there is no interlacing, it is more accurate to display them with one blank space between each. So the EPPLE ][ has two times 192, or 384, vertical pixels in its display. Horizontally there are 280 pixels, but each could also be shifted right one-half dot, allowing for two times 280, or 560, different horizontal displayable positions. To emulate this, the EPPLE ][ shows each emulated pixel as two pixels wide, and displays an emulated half-dot shift as an actual one pixel shift. So the display area of the EPPLE ][ is 560x384. There is an informational area below and to the right of the emulated display that shows various statistics of the emulator. So the total screen area used by the EPPLE ][ is a standard 640x480 pixels.

The EPPLE ][ can run in either full-screen mode, or within a window. Use the F3 key to toggle between the two.

The area at the bottom and the right of the EPPLE ][ display show various information about the emulator.

The Disk ][ Controller card emulates the floppy disk controller card and associated disk drives in the original Apple ][ systems. In the emulator, each card has two drives attached to it, referred to as drive 1 and drive 2. The floppy disks themselves are represented by a “nibble” image of the contents. The emulator emulates the hardware, but to be of any use, you will need to provide the firmware ROM code.

To use a disk card and drives, add these lines to your epple2.conf file, for example:

The first line uses the slot command to insert a disk contoller card into slot 6, which is the standard slot used for disk cards. The next line uses the import command to load the card’s ROM with the disk controller firmware. This firmware is known as the “bootstrap” or “P5” ROM code. It is seen by the Apple ][ at memory addresses $Cs00-$CsFF, where s is the slot number (so in the common case of the card being in slot 6, the ROM is at $C600-$C6FF). The firmware is copyright by Apple, and is available from the Apple II Library.

You can also load a floppy disk image (nibble format) into the drive,either by putting the load command into the epple2.conf file, or by using the command prompt in the emulator (F5 key). For example, you could load the DOS 3.3 system master into slot 6, drive 1, with this command

The language card emulates an Apple 16K RAM card, commonly called a Language Card. To use a language card, add this line to your epple2.conf file:

Note that DOS and ProDOS will make use of a language card only if it is in slot zero.

The language card has RAM at addresses $E000 through $FFFF, as well as two banks of RAM at addresses $D000 through $DFFF. A program switches between these RAMs and/or the motherboard ROM by using the I/O switches at $C080 through $C08F.

The information area of the Epple ][ will show the current state of the language card as follows:

An overview of the I/O switches that control the language card is provided by Jim Sather in Understanding the Apple II, p. 5-30, Table 5.4, as follows:

^* Writing to expansion RAM is enabled when WRTCOUNT reaches 2.

The firmware card emulates a (modified) Apple Firmware card. The firmware card is simply an alternate ROM, at addresses $D000 through $FFFF, that is switched using the I/O switches at addresses $C080 through $C08F. In order to make use of the firmware card, you will need to load the ROM with a binary image from a file on disk. For example, to insert an Integer BASIC firmware card into the emulator, add these lines to your epple2.conf file:

For an Applesoft BASIC firmware card, use these:

Note that the addresses specified in the epple2.conf file for the rombank are based on the beginning of the bank ROM itself. For example, specifying 1000 (which is 1000 hex) represents the final memory address of $E000, because the bank ROM is always based at address $D000.

The idea is that you would load your motherboard with, for example, Applesoft BASIC and the Autostart Monitor ROM (to emulate an Apple ][ plus), and then install a firmware card with Integer BASIC and the old Monitor. Booting with DOS 3.3, then, would allow you to type FP to use Applesoft BASIC, or INT to switch to Integer BASIC.

Note that DOS and ProDOS will make use of a firmware card only if it is in slot zero.

Jim Sather, in Understanding the Apple II, on pages 6-18 through 6-21, explains how to modify a firmware card to allow independent switching of the $F800-$FFFF ROM memory. This area is occupied by the Monitor, so it is primarily intended to allow the user to switch between the old Monitor and the Autostart Monitor, independent of switching between Integer and Applesoft BASIC. The EPPLE ][ firmware card emulates this behavior.

The information area of the EPPLE ][ will show the current state of the firmware card as follows:

The clock card emulates a ProDOS-compatible real-time clock card for the Apple ][. To use a clock card, you will need to configure the EPPLE ][ to insert one into a slot, typically slot 4. You will also need to load the card with its ROM code, which is provided with the emulator in the clock.ex65 file. For example, add this to your epple2.conf file:

Of course you may need to adjust the path for your particular system.

To verify that the clock card is working correctly, you can run the following Applesoft program to retrieve the current time from the clock card and print it. This program assumes the card is in slot 4.

The card returns data (into the GETLN input buffer at $200) in the following format:

mm,ww,dd,hh,nn,ss,000,yyyy,Time Zone,v

Note that only mm,ww,dd,hh,nn fields are used by ProDOS. The other fields, ss,000,yyyy,Time Zone,v, are an EPPLE ][ extension. Also note that ProDOS was not designed to work for years past 2007, so ProDOS will show the incorrect year, but the other fields will be accurate. I believe patches exist for ProDOS to fix this.

The “standard input” card doesn’t emulate a real piece of hardware; rather, it reads characters from standard input (stdin) (of the EPPLE ][ emulator).

To use a standard input card, add these lines to your epple2.conf file:

That will insert a stdin card into slot 2, and then load its ROM image into the card. The stdin ROM is provided with the EPPLE ][ distribution.

For example, if you have a stdin card installed in slot 2, start the EPPLE ][ emulator from the command line, and at the Applesoft prompt, type IN#2. Then you can switch back to the command shell, and whatever you type will be fed into the emulated Apple. Use RESET or IN#0 to go back to normal.

The “standard output” card doesn’t emulate a real piece of hardware; rather, it acts similar to a printer card, but instead of sending characters to a printer, it sends them to standard output (stdout) (of the EPPLE ][ emulator).

To use a standard output card, add these lines to your epple2.conf file:

This will insert a stdout card into slot 1 (which is the typical slot for a printer card), and then load its ROM image into the card. The stdout ROM is provided with the EPPLE ][ distribution.

For example, if you have a stdout card installed, at the Applesoft prompt, type PR#1. Whatever you type next will be echoed to standard output. Type PR#0 to stop echoing.

cassette new <file-path>

This creates a new empty file (on the host computer) that represents a cassette tape image. The file must not already exist.

cassette load <file-path>

This loads an existing file (from the host computer) containing a cassette tape image. The tape is automatically positioned at its beginning (fully rewound).

cassette unload

This removes the file from the cassette tape. Note that you must manually save the file using the cassette save command (described below).

cassette rewind

This command “rewinds” the cassette tape, positioning it at the beginning of the tape (for subsequent reading). You do not need to rewind the tape before saving or unloading it, of course.

cassette save

This command saves the changed tape to the file. Note that the display will show an asterisk * next to the file name if there are unsaved changes that need to be saved. Unsaved changes will be lost without warning if the file is unloaded or if you quit the program.

Start up the emulator with Applesoft ROMs for this tutorial. Enter a simple Applesoft program, just as an example, that we are going to save to a cassette tape image file.

We first need to load a tape image file into the cassette machine. Enter command mode by pressing F5, then make a new tape image file.

This will create a new, empty tape file image named hello.tap in the current default directory. (We could have specified a full path name for the file if we wanted to place it in a different directory.) Notice that the emulator now displays the name of the tape image file, along with the position and length of the tape image, which is now 0/0.

Next, we tell Applesoft to save the program to the cassette. For this, we just use the SAVE command. Note that this is not the DOS SAVE command; the DOS command has a file name after SAVE. We just use SAVE with no file name.

It will take 10 seconds or so for it to save. Notice that the current position of the tape is counting up as the Apple saves the program. When it is finished, you need to save the changes to the file. Press F5 and enter the emulator command to save the tape image file.

We can now unload the file from the emulator (which is like ejecting the tape from the cassette player).

To load the saved program (from the previous section) into the Apple again, we will need to first load the tape image file back into the cassette machine. Press F5 to enter command mode and load the image file.

This will load hello.tap (in the current default directory). Notice the emulator now displays the name of the tape image file, along with the position and length of the tape image, which in this case is 0/33481.

Next, we tell Applesoft to load the program from the cassette. For this, we just use the LOAD command. Note that this is not the DOS LOAD command; the DOS command has a file name after LOAD. We just use LOAD with no file name.

It will take 10 seconds or so for it to load. Notice that the current position of the tape is counting up as the Apple loads the program. When it is finished, the program will be loaded.

The format of the tape image file is unique to the Epple ][ It is stored in a low-level format that represents the waveform that the Apple writes to the cassette tape.

The file is a binary format. Each byte in the file represents the length of one half of one cycle (of voltage level variation) written to the tape. The length is in 10-microsecond units.

For example, a tape image file might have the following binary bytes (in decimal): 65 65 65 65 65 20 25 50 50 25 25 25 25 50 50 Since each byte represents a 10-microsecond unit, these bytes represent the following half-cycle lengths in microseconds: 650 650 650 650 650 200 250 500 500 250 250 250 250 500 500 The meaning of these half-cycle lengths to the Apple is as follows:

where HEADER is a header section the Apple writes (to skip any unrecordable leader section on a real cassette tape); sync is a synchronization cycle; and the subsequent cycles are the actual bits of data saved on the tape. A 500-microsecond cycle (which is stored in the file as two 250 microsecond half-cycles) represents a zero bit, and a 1-millisecond cycle (which is stored in the file as two 500 microsecond half-cycles) represents a one bit.

Install MSYS into C:\msys\

Install MinGW into C:\msys\mingw\

For more information on MinGW and MSYS, see http://www.mingw.org/.

At http://www.libsdl.org/ find the download page. Download the “Development Libraries” for Win32/mingw, for example:

SDL-devel-1.2.13-mingw32.tar.gz (Mingw32)

and save it to your MSYS home directory (for example, C:\msys\home\Administrator). Run MSYS, and at the bash prompt, go to your home directory and untar the SDL archive to your home directory:

Then follow the instructions to install SDL, for example:

Download the Epple ][ Source Distribution and save it to your MSYS home directory (for example, C:\msys\home\Administrator). Run MSYS, and at the bash prompt, go to your home directory and untar the epple2 source distribution tar file. For example:

Then build as follows. I recommend doing a VPATH build, where you build into a different directory than the source directory. To accomplish this, create a new directory for building, somewhere, such as:

Then run configure from there. For the MSYS build to work, you need some extra parameters to the build, and you could also add some compiler options to optimize the build. For example (from the buildepple2 directory you just created):

If all goes well, it will build without any errors. If you get errors about not finding SDL.h, make sure SDL is installed, and make sure the configure command is correct. (If you just run configure without the options shown above, you will get this error at build time.) The result of the build (on Windows platform) is

installer/epple2.msi

which is an installable file for Windows. To install epple2, just double-click on this file from Explorer.

Copyright © 2009,2012, by Christopher A. Mosher, Shelton CT, USA.

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