CPU Configuration
The most significant variable is selecting which CPU to emulate.
The first Wang 2200 systems used the 2200A, 2200B, 2200C, 2200S, or 2200T
CPUs. The differences between these were mostly the amount of microcode.
These all ran versions of Wang BASIC from ROM.
The 2200 VP (and later models) used a number of different implementations
of the VP microarchitecture but were largely the same. Select this
for 2200 VP emulation running Wang BASIC-2. Note that the VP series
didn't have BASIC in ROM and instead required a boot disk containing the
BASIC microcode. For VP emulation the system must have at least on
disk controller in order to load microcode.
To configure how much RAM the machine has, from the top level menu pick
"Configure", then the submenu "Configure System...". You should see
a window that looks something like this one:
Click on the pull-down list item labeled "RAM" and pick how much RAM
you'd like your system to have:
The RAM size options shown above are all the ones valid for a real 2200T
CPU. When the emulator is configured with a 2200 VP CPU, the RAM
choices are different to reflect what was valid for that system.
I/O Configuration
The system emulated has six I/O slots. What gets plugged into each
slot is up to the user. Just like a real 2200, slots are completely
symmetric, meaning that any card can be plugged into any available slot.
Currently, there are only five types of I/O cards emulated:
-
6367 keyboard controller
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6312A display controller (64x16)
-
7011 display controller (80x24)
-
6541 disk controller
-
7079 printer controller
In real life, most cards could be assigned to just about any address, but
certain addresses were the preferred addresses, just to keep system configuration
less complicated. Also, certain devices had to be present at certain
I/O addresses, since at power up, the microcode expected an input device
at address 001 and an output address at 005.
Select "Configure/Configure System..." from the top-level menu and you'll
get this dialog:
For each of the slots, you can pick one of the available card types.
For example, here's how to add an 80x24 display controller:
A card can be removed from a slot by selecting the "(vacant)" device
type for the slot.
After selecting the new device, the I/O address of the card will still
need to be assigned. Click on the pull-down list for the I/O address
for the slot just modified; in this example,
After making changes, either accept them by pressing the OK
button, or cancel your actions by pressing the Cancel button.
Optionally, you can abort your changes and start over by pressing the Revert
button.
If you press OK and there is something wrong with the
configuration you've set up, you'll get one of the following warning messages
explaining what is wrong. The first two are self explanatory:
The warning above means you have added a card to a slot, but forgot
to assign it an I/O address.
The warning above means that you have assigned the same I/O address
to two (or more) cards. I/O address assignment must be unique.
CRT Configuration
The appearance of the CRT portion of the emulation is controlled via the
"Display Configuration" dialog. This dialog is invoked via the "Configure/Configure
Screen..." menu. The dialog is shown immediately below.
When selections are made on this dialog, the change is immediately reflected
in the emulated CRT display.
CRT Font
The emulator can use a few different font sizes using the system Courier
font. This produces easy reading text but it has some drawbacks.
One drawback is that the original Wang font had characters that the system's
Courier font doesn't support or has only very rough equivalents for.
More importantly, part of the fun of emulation is trying to be authentic
as possible. To that end, the dot matrix font used in WangEmu was
obtained by reading the character generator ROM from a real Wang 7011 CRT
controller.
System Courier, 12 point
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Wang Dot Matrix, 1:2 Scaling
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The Display menu can be used to choose whatever font size appeals most
to the user. After changing the font size, it is likely that the
user will need to resize the CRT window to better match the emulated display
size. Note too that the emulator maintains separate font choices
for when the emulator is in fullscreen mode and not; the dialog changes
only the selection for the current mode.
CRT Color
The default color scheme chosen for the Wang emulator is bright green on
very dark green. This most closely matches the look of the Wang CRT
display. However, the user can also change to use either the "white"
or "blue" color schemes. The "blue" scheme seems like an unlikely
choice, except that it is quite readable, and there was an early Wang brochure
with a mocked up display that used that color scheme.
Here is what the three look like together:
green phosphor
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white phosphor
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white on blue
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Contrast/Brightness
The sliders on the Display Configuration dialog roughly emulate the contrast/brightness
controls of an original Wang terminal.
Statistics
Although it has nothing to do with the CRT, this dialog allows user control
of whether or not emulation performance statistics appear in the status
bar of the CRT frame.
For example, the statusbar above indicates that 730 emulated seconds
of CPU time had elapsed since the beginning of the simulation and that
the emulation was running at 42 times the speed of an actual Wang 2200.
Miscellaneous Configuration
There are a few configuration choices that don't fall into one of the broad
categories above.
Some of the configuration state is implicitly controlled. Just
about all of the windows and dialogs of the emulator retain their size
and position between invocations. The Wang emulator also maintains
the most recent directory where a text script file was read, where a screen
capture was most recently saved, where a virtual disk image was located,
and where printer output was saved.
Keyword Mode
The Wang 2222 keyboard had two modes of operation, controlled by a toggle
lever on the left side of the keyboard. In "A/a" mode, the keyboard
acted much like a typewriter. Shifted keys produced capital letters
and unshifted keys produce lower case letters. If the mode switch
was set to "Keyword/A" mode, shifted keys produced keywords (e.g., "PRINT
" and "FOR "), while unshifted keys produced capital letters.
WangEmu supports 2222 keyboard emulation via a checkbox in the lower
left corner of the CRT display. The two modes are shown here:
Checking the box causes shifted letters to produce keywords and unshifted
letters to produce their capital letter. Another way to toggle the
state is to select the "Configure/Keyword mode" menu item, or to use the
keyboard sequence Alt+K [Mac: Cmd+K].
SF key toolbar
This item is a toggle that enables or disables the display of a toolbar
on the CRT window. The toolbar contains a graphical depiction of
the 16 special function keys plus the EDIT key. This toolbar is especially
useful on the Mac platform because the function keys aren't all available
nor do they work in concert with the shift key.
Here is what the top of the CRT window looks like without a toolbar:
and here is what it looks like with the toolbar enabled:
There are 16 special function keys; holding down the shift key while
clicking on one of the buttons produces the Wang special function keys
16 to 31. Some of the buttons have a label above the special function
key number, just like a real Wang keyboard. These show the effect
that the keys have in EDIT mode.
Fullscreen Mode
WangEmu normally runs in a window frame of a size chosen by the user.
The user may make the window as big or small as desired and WangEmu will
remember this. No matter how large or small, though, this frame will
always have a title bar, a menu bar, a status bar, and left and right frame
margins.
By selecting the "Configure/Fullscreen" menu item, or by using the keyboard
shortcut Alt+Enter [Mac: Cmd+Enter], WangEmu will toggle into and
out of fullscreen mode. Fullscreen mode is where the program will
take over the whole computer screen. It is different than a maximized
window in that there is no title bar, no status bar, and no left and right
margins. This mode allows maximum use of screen real estate and comes
closes to emulating a real 2200 CRT. Because the fullscreen vs. normal
sized window are likely to have very different sizes, WangEmu maintains
separate font style preferences for these two modes.
Logically this option should live in the Display Configuration dialog,
but since it is likely to be changed more often than those other CRT-related
options, it has been made more accessible to the user.
Realtime Disk Emulation
When the emulator accesses a virtual Wang disk image, the user has the
choice of letting the access complete as quickly as possible or to emulate
the timing of the original Wang disk system. This choice is controlled
by a checkbox on the System Configuration dialog. That box is highlighted
below:
Note that the exact timing behavior of the disk is affected by three
things, including this setting. Even if the realtime emulation option
is chosen, if the emulation speed is set to "unregulated," then the actual
time things take is proportional the emulated CPU speed. Finally,
the emulator supports three different media formats: 5.25" floppy, 8" floppy,
and hard disk, each with its own timing profile.
Enable/Disable Warnings About Accesses to Unpopulated I/O Addresses
The Wang I/O structure supports 255 unique I/O addresses (address 0x00
is reserved to mean "address nothing.") Programs can arbitrarily
attempt to perform I/O on any of these addresses. Because the emulator
supports a limited number of I/O devices or may be configured differently
from the expectations of a running program, the emulator will by default
warn when a program selects an address that doesn't have a device at the
address.
Whether to warn or not is controlled globally by the flag on the System
Configuration menu, shown highlighted below.
Keyboard Tieing
Although probably 99.9% of the Wang 2200's were used with a single keyboard
(that is, until the MVP came out), there was nothing to prevent a person
from plugging multiple keyboard controllers into one CPU. WangEmu
also allows it. However, that presents a problem, as a PC is even
more likely than an old 2200 to have a single keyboard. WangEmu solves
this by allowing the user to specify where keystrokes directed to a given
CRT screen should map to in the range of keyboard addresses.
If the system is configured to have a single keyboard, then the emulator
assumes all keystrokes are to go to the single keyboard controller (which
must, be necessity, be at address 01), and the top level Configure menu
list looks like this:
However, say two keyboards are configured for the system, at I/O addresses
01 and 02. The top level Configure menu changes to look like this:
By selecting "Tie to /0nn", any keys typed while the window has focus
will be caught by the keyboard controller emulation at I/O address nn.
It is possible to have the input from one CRT to go to any of N different
keyboards, and it is also possible for N different CRT windows to get mapped
to a single keyboard controller, or anything in between.
