Config File

Bizmuth keeps its settings in one JSON file, ~/.bizmuth/config.json: a .bizmuth folder in your home directory on every platform, C:\Users\NAME\.bizmuth\config.json on Windows. Preferences edits most of it; the rest is written by Bizmuth itself or set by hand.

{
  "roms_dir": "/Users/me/Documents/Bizmuth",
  "default_machine": "next",
  "debug": { "protocol": "adp", "adp_port": 11001 },
  "esp": { "endpoint": "esp", "port": 11002 }
}

A key left out takes its default, so a file holding only the keys above is complete. A file that cannot be read is replaced by the defaults.

A command-line flag overrides the file for one run and does not change it. --roms-dir is the exception, and is written back. --config FILE reads and writes another file in place of this one.

Edit the file while Bizmuth is closed. Bizmuth writes the window, view and card settings back when it quits, over any change made while it ran.

Top-level keys

Key	Default	Meaning
`roms_dir`	none	the ROM folder; none means first-run setup asks
`default_machine`	`"next"`	`48k`, `128k`, `plus2a`, `plus3` or `next`
`window`	none	`x`, `y`, `width` and `height` of the window, written at quit

`paths`

Key	Default	Meaning
`sd0`, `sd1`	none	the card image in slot 0 and slot 1
`sd0_read_only`, `sd1_read_only`	`false`	attach that slot copy-on-write

`view`

Key	Default	Meaning
`scale`	`2`	window scale, 1 to 4
`maintain_aspect`	`true`	letterbox instead of stretching
`show_statusbar`	`true`	the status bar
`show_toolbar`	`true`	the toolbar
`autohide_statusbar`	`false`	hide the status bar in full screen
`fullscreen`	`false`	start full screen
`scanlines`	`0`	scanline weight: 0 off, 1 25%, 2 50%, 3 75%

`audio`

master, dac, ay and beeper, each a multiplier on that source’s level, 1.0 by default. 1.0 is the level the FPGA’s mixer gives. Preferences shows them in decibels.

`input`

Key	Default	Meaning
`cursor_mode`	`"next_nav"`	present in the file and not read: the arrow keys start in the machine’s default mode, as Keyboard and Controllers describes
`mouse_enabled`	`true`	the Next’s Kempston mouse
`next_joy_left`	`"sinclair2"`	what the Next’s left port presents: `sinclair1`, `sinclair2`, `cursor`, `kempston1`, `kempston2`, `md1`, `md2` or `io`
`next_joy_right`	`"kempston1"`	the same, for the right port
`classic_kempston_enabled`	`true`	a Kempston interface on the classic machines
`classic_interface`	`"none"`	a keyboard joystick interface on the classic machines: `none`, `sinclair1`, `sinclair2` or `cursor`

`controller`

Key	Default	Meaning
`deadzone`	`0.5`	how far, 0 to 1, a stick moves before it counts as a direction
`devices`	empty	per gamepad, by the name the system gives it: its `port` and its `bindings`

A device’s port is left, right or none. Its bindings map each control (up, down, left, right, fire, fire2, a, start) to a list of inputs, any of which drives it:

"controller": {
  "deadzone": 0.5,
  "devices": {
    "Xbox Wireless Controller": {
      "port": "left",
      "bindings": { "fire": ["south", "north"], "up": ["dpad-up", "leftsticky+"] }
    }
  }
}

A control a device does not bind uses the default binding listed on Keyboard and Controllers.

`emulation`

Key	Default	Meaning
`max_speed`	none	a ceiling on the Next’s CPU speed: 0 3.5 MHz, 1 7, 2 14, 3 28; none for no ceiling
`mem_wait`	`true`	the 28 MHz memory wait state
`im2_daisy`	`true`	the IM2 hardware interrupt vector
`rtc`	`true`	a real-time clock fitted

--max-speed, --no-mem-wait, --no-im2-daisy and --no-rtc override these for one run.

`debug`

Key	Default	Meaning
`protocol`	`"none"`	the debug server started: `none`, `adp` or `dzrp`
`adp_port`	`11001`	the ADP port

--debug-protocol both starts both servers for one run; the file holds one. See ADP.

`esp`

Key	Default	Meaning
`endpoint`	`"null"`	what the Next’s ESP serial line is wired to: `null` for nothing, `loopback`, `bridge` or `esp`
`port`	`11002`	the TCP port `bridge` listens on

An unknown endpoint is treated as null, with a warning.

`update`

Key	Default	Meaning
`check_enabled`	`true`	check for a new version on startup
`interval`	`"weekly"`	`daily`, `weekly` or `monthly`
`last_check`	empty	the date of the last successful check, written by Bizmuth
`skip_version`	empty	a version you chose not to be told about

`overlay`

Key	Default	Meaning
`zoom`	none	the overlay’s magnification on top of the display scale; none chooses it from the display

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