L4TIMER selects the game clock (L4TIME.CPP): FAST = HMI SOS interrupt
clock at 28 Hz, unset = polled 18.2 Hz BIOS tick. Not a speed switch --
finer time quantum, smoother sim dt and timing cadences.
Per the operator: the flag tracked the deployed fleet's hardware --
original Tesla pods ran Pentium Pro 90s (SLOW), later fleets Pentium
Pro 200s (FAST). The emulated pod has no ISR-headroom constraint, so
FAST is our default from here on.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Enabling gauges crashed (null-this, illegal 0x478). Root cause was NOT video:
the MUNGA main heap (fixed 6MB default) exhausted loading gauge images. The
heap size comes from getenv("HEAPSIZE") (BTL4OPT.EXE @0x401076; default
0x600000); the pod's PARAMETR.BAT sets it (:POD=15MB, :REVIEW/:LOOP=32MB) but
our minimal setenv launch never did. memsize is irrelevant (it's the game's
own heap, not DOS memory -- verified memsize=127 still gave 6MB). Pods have
32MB RAM so 15MB fits.
Fix (no binary patch): set HEAPSIZE=15000000 + L4GAUGE=640x480x16 in
gauge.conf. Game now runs sustained with gauges on (500+ frames); the VESA
640x480x16 mode switches fine on our emulated S3 and the cockpit instrument
panels draw (DISPLAY/PROGRAM/ENG DATA/TRIGGER CONFIG...).
patch_btl4opt.py also gained Verify_Failed (DEBUG-build assertion) neutral-
ization -- release-equivalent robustness, separate from the heap fix.
Known-open (GAUGE-NOTES.md): the framebuffer renders only a top strip,
garbled -- the game bank-switches via a hardcoded far pointer in L4GAUGE.INI
(C000:2616, the STB Horizon+ card's VESA WinFuncPtr) that isn't valid on our
emulated S3, so only the first bank(s) page in. Fixing bank-switching (or an
LFB mode) is next; then the full buffer can be split into the six displays.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
The VDB is the ISA card that fans the PC's Cirrus Logic framebuffer to the six
secondary cockpit displays (5 mono + 1 color), dividing the pixel clock. From
the driver (CODE/RP/MUNGA_L4/L4SVGA16.ASM, L4VB16.CPP; "Adam's port decoder
design" -- Adam G., VWE hardware):
0x300/0x308/0x310 three VGA-DAC-style palette groups
0x31A / 0x319 splitter high-color clock divider ON / OFF
New emulated VDB device in vpxlog.cpp at I/O 0x300-0x31A (active when logging,
disable with VDB=0): decodes palette write-address/data/mask/read-address and
the clock strobes, recording palette contents + splitter state so the six-
display encoding can be decoded later. Validated: with gauges enabled
(gauge.conf, setenv arg4=g) the game issues "splitter clock ON (0x31A)" ->
captured. The board is write-only (game never reads it, per driver + owner),
so its absence is not the crash.
Crash diagnosis (BTL4OPT.EXE CODE+0x123B): the faulting routine is a heap
free() with boundary-tag coalescing; it was handed a garbage block pointer
(value 2). Symptom of upstream corruption, reached only when the RIO is in
sync and the sim advances. HISTORY.md gains a "Cockpit display hardware -- the
VDB" section with the attribution.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
CydandClaude Fable 5