TFX configuration and display modes

These notes describe the September 1994 TFX 2.05 installation. CONFIG.EXE sets hardware and startup defaults; the in-flight configuration menu, opened with the backtick/accent key, adds simulation and display preferences. Both use the same TFX.CFG. The game’s reader and writer establish that the flight menu persists REALISM, DETAIL, JOYSCALE and HUDCOL while preserving the other lines.

HUD intensity: HUDCOL

HUDCOL=125

HUDCOL controls the green component of HUD palette entry 6. Native 0x73f1b writes its low byte to palette offset 0xf99b, then 0xc770c uploads the bytes unchanged. The six-bit VGA DAC ignores the upper two bits: the compiled default 125 becomes green level 61. The flight input routine clamps the word to 90–127, corresponding to DAC levels 26–63. Larger values within that range give a brighter HUD. The configuration reader itself accepts an integer into a 16-bit field; the clamp happens during flight.

This corrects the earlier interpretation as a palette-index selector. The C++ reconstruction checks the original complete palette generation and differential uploader separately, retaining raw bytes until DAC presentation rather than relaxing palette-file validation.

The native adjustment routine checks raw scan codes 0x15 and 0x16, corresponding to Y and U on a QWERTY keyboard. Holding Y increments the component and brightens the HUD; holding U decrements it and dims the HUD. No Shift modifier is required. Starting at 125, Y has only two remaining steps before reaching the brightest setting, which can make a brief adjustment difficult to notice.

The scanned English manual agrees in its HUD section: Y decreases intensity and U increases it. Its laser-designator section specifies Z. The keyboard initialiser likewise binds scan code 0x2c, QWERTY Z, to the designator handler.

The unofficial tfxkeys.txt instead lists Y for the designator. Its German distribution markings and keyboard-specific symbols suggest a QWERTZ layout, whose Y/Z keycaps occupy the opposite physical positions. That is a likely explanation for the discrepancy, rather than evidence for an alternate binding decoded from this executable.

The game’s HUD setting reader and writer preserve this value. HUDCOL need not appear in the initial file: the flight menu’s save routine adds it.

Other retained flight shortcuts, aliases and cheat combinations are mapped separately in keyboard bindings.

REALISM field order

The native reader accepts seven comma-separated integers, and the writer writes them in this order:

The five on/off controls in the realism menu follow G effects, which has three choices. Auto recovery is in the main configuration menu, but its value is stored at the end of REALISM.

For example:

REALISM=2,1,1,1,1,1,0

This selects realistic G effects, enables all five realism switches, and disables auto recovery. The reader zero-initialises all seven temporary values before conversion, so an older six-value line leaves auto recovery off. The flight menu subsequently writes the complete seven-value form.

The scanned manual describes a separate “loss of control” item; the decoded 2.05 menu instead labels its second field precipitation. The field names above come from the actual menu label table and the reader/writer assignments, rather than assuming that the manual’s prose order describes this version.

Recognised keywords and memory flags

The game’s configuration dispatch table recognises:

CONTROL, DETAIL, MODEL, SOUNDFX, MUSIC, STICK, JOYSTICK, LANG, LOWMEM, BLASTER, ULTRASND, IRQBASE, REALISM, JOYSCALE, HUDCOL.

START.EXE separately recognises:

SWAP, SOUNDFX, MUSIC, IRQBASE, BLASTER, ULTRASND.

The game dispatch routine and launcher both ignore unknown keywords. There is no cockpit, resolution or colour-depth keyword hidden behind the existing defaults. HUDCOL is recognised by the game although the standalone setup program does not offer it.

LOADLOW survives as a field in CONFIG.EXE, but neither the launcher nor the game recognises it in any of the five retained installations. In the reference setup executable, its save path at file 0x2fe79 computes LOADLOW = (SOUNDFX == 0): sound effects disabled gives 1, enabled gives 0. Its name suggests an older low-memory loading arrangement, but its intended historical use remains unestablished. Changing it has no active effect in the reference launcher/game, and it does not enable or disable HIMEM.

LOWMEM is a separate, active game setting. Its consumers include camera/view handling at 0x85348 and 0x855ec, which select restricted view paths for the low-memory arrangement. It is not a screen-resolution setting. The supplied installation notes explicitly say that HIMEM/EMM386 are not required, although the game can operate with them; the DOS extender’s memory interfaces are separate from these game preferences.

Graphics modes

The game’s video initialiser sets BIOS mode 0x12, then 0x13, then programs the VGA sequencer/CRTC/graphics controller for unchained planar drawing. The first mode is an intermediate setup step; the active game display is 320×200 with 256 palette colours. Each pixel stores an 8-bit palette index; VGA DAC colour components have six-bit precision.

There is no selectable higher-resolution, 16-colour or true-colour path in the reference game’s configuration or video setup. The manual’s VGA/SVGA compatibility means that an SVGA card can display this VGA mode, rather than providing an SVGA-resolution option. Cockpit, virtual cockpit, full view and smaller flight windows change the viewport within the same framebuffer. DETAIL changes world detail, while MODEL chooses the flight model; neither selects a different display mode.

Verification

check_configuration.py loads and relocates the original executables in Unicorn. Its report records native configuration dispatch, 15 Y/U/clamp cases, the Z callback binding, the exact VGA mode/register sequence and five CONFIG.EXE LOADLOW cases. REALISM ordering is checked against the original store instructions and menu label pointers. These are isolated native checks, not a claim that a full mission has been emulated.