Preferences

File ▸ Preferences (Ctrl+,) holds the settings that persist between sessions, in nine tabs. On macOS it is in the Bizmuth application menu, on Cmd+,.

Changes apply when you press OK. Audio levels apply as you drag them, and Cancel restores the levels the dialog opened with.

A setting marked next launch below is saved at once and takes effect the next time Bizmuth starts. Every other setting also applies to the running machine when you press OK.

General

Setting	Effect
ROM directory	the folder the ROMs are read from, as first-run setup chose it. Next launch.
Default machine	the machine Bizmuth starts as: 48K, 128K, +2A, +3 or Next. `--machine` overrides it for one run. Next launch.

Media

The SD card images for the Next’s two slots, and a read-only flag for each. A card set here is attached at every launch, as Media ▸ SD0 ▸ Attach attaches it for the session.

Changing a slot’s card or its read-only flag attaches the card at once and resets the Next, as the Media menu does. A slot left untouched in the dialog is left alone, so a card attached from the Media menu during the session is not replaced by the saved one.

Display

Setting	Effect
Window scale	1× to 4× the native display size, as View ▸ Scale
Scanlines	off, 25%, 50% or 75%
Maintain aspect ratio	letterbox or pillarbox the picture, in place of stretching it to the window
Show toolbar	the icon toolbar
Show status bar	the bottom status bar
Hide the status bar in full screen	the status bar is hidden while the window is full screen
Start full-screen	Next launch.

Input

Setting	Effect
Enable mouse	the Next’s Kempston mouse. Turning it off releases a captured pointer
Next joystick, left port	what the Next’s left port presents to software: Sinclair 1, Sinclair 2, Kempston 1, Kempston 2, Cursor, MegaDrive 1, MegaDrive 2 or User I/O. NextZXOS may change it after boot
Next joystick, right port	the same, for the right port
Kempston interface	a Kempston interface on port `$1F` for the classic machines
Classic joystick interface	None, Sinclair 1, Sinclair 2 or Cursor: a joystick interface on the classic machines that presents the joystick as keys. It can be fitted alongside the Kempston interface

Controller

The tab lists every connected gamepad, and every pad configured before. With none connected it says so; connect a pad and reopen Preferences.

Setting	Effect
Device	the pad being configured
Emulated port	Left, Right or None. One pad per port: choosing a port for one pad takes it from any other
Up, Down, Left, Right, Fire (B), Fire 2 (C), A, Start	press Bind, then the pad’s button or stick direction
Reset device to defaults	restores the default bindings listed on Keyboard and Controllers

A pad with no saved settings takes a port by the order it connected in: the first the left port, the second the right.

Audio

Master, DAC, AY and beeper levels, in decibels from −48 to +12. 0 dB is the level the FPGA’s own mixer gives, and the bottom of the range mutes the source.

Debug

Setting	Effect
Debug protocol	`none`, `adp` or `dzrp`; `none` on a fresh install. Next launch.
ADP port	11001 by default. Next launch.

Advanced

Setting	Effect
Maximum CPU speed	uncapped, or a ceiling of 3.5, 7, 14 or 28 MHz on the Next’s CPU speed
28 MHz memory wait	the wait state the Next’s memory inserts at 28 MHz. On by default
IM2 hardware daisy-chain vector	the Next’s interrupt controller supplies the IM2 vector. On by default
Real-time clock fitted	whether the Next has a real-time clock

These four take effect the next time the machine starts.

Updates

Whether Bizmuth checks for a new version on startup, and how often: daily, weekly or monthly.

Settings saved at quit

These are saved when Bizmuth quits, without appearing in Preferences:

the window’s position and size
the View options: scale, aspect ratio, toolbar, status bar and scanlines
the attached SD cards and their read-only flags

A card attached with --sd or --sd1, and the read-only flag --sd-ro sets, apply to that run only. They are saved only where the card was changed during the session.

Settings file

The settings are in ~/.bizmuth/config.json, plain JSON that can be edited while Bizmuth is closed; see Config File. --config FILE reads and writes another file in its place, so a trial run cannot change your settings.