The Alpha [+] dialog exposes the configuration-file settings below. Settings marked harmful should normally remain at their defaults. Main Memory, JIT, Auto-Exit, and Auto-Idle also have controls in Virtual Alpha Base Settings; Auto-Idle is the only one repeated in this dialog.
image (new-configuration value: <base>.nvr; omitted-property fallback: nvram.img)
Pathname of the 16KiB NVRAM image. This file is the equivalent of non-volatile RAM on a physical Alpha and retains firmware settings such as boot parameters. The configuration utility gives a new configuration an image alongside the configuration file; a hand-edited configuration that omits this property uses nvram.img.
jit_memory (default: 0, increment: 64M, maximum: 2G)
Maximum address space reserved for translated JIT code when JIT is enabled. Zero automatically selects half of physical host memory, rounded down to a 4MB boundary and capped at 2GB; if host-memory discovery fails, zero selects 2GB. Avanti normally commits the reserved range incrementally in blocks of at least 4MB. If the first block cannot be committed, Avanti releases that reservation and retries by reserving and committing the entire configured buffer at once; this fallback can immediately consume the full commit charge.
Note: If running on a Windows host system equipped with more than 32GB of memory and the following error is encountered, set the jit_memory parameter to 2GB.
Unable to reserve JIT buffer area: error 87: The parameter is incorrect.
bwx (default: true)
Advertises and enables the Alpha Byte/Word Extension (BWX). Disable it only when intentionally testing an EV4-only software path; guest software that requires BWX will no longer run.
cix (default: true)
Advertises and enables the Alpha Count Extension (CIX). Disable it only for deliberate compatibility testing; guest software that requires CIX will no longer run.
fix (default: true)
Advertises and enables the Alpha Floating-point Extension (FIX). Disable it only for deliberate compatibility testing; guest software that requires FIX will no longer run.
mvi (default: true)
Advertises and enables the Alpha Motion Video Instructions (MVI). Disable it only for deliberate compatibility testing; guest software that requires MVI will no longer run.
jit_patterns (default: true)
When JIT is enabled, recognizes selected Alpha instruction sequences and translates each recognized sequence as a unit. This setting has no effect while JIT is disabled.
auto_idle (default: false)
This is the same setting as the Auto-Idle check box in Virtual Alpha Base Settings, not a second idle mechanism. See that topic for its behavior and performance guidance.
timing_window (default: 1000; range: 1 through 1000000)
Scales the emulator's host-timer calibration window, with 1000 representing the normal 1.0 factor. Changing it alters the timing loop and effective timer-resolution floor and can cause clock inaccuracy or poor responsiveness. Retain 1000 unless directed to change it for a diagnosed timing problem.
