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Crome JavaScript Scripting API

Technical reference for the legacy Crome ROM editor JavaScript API used for developing scripts, ROM handlers, and plug-ins.

Updated June 20, 2026 Advanced 0

Crome exposes a JavaScript API for extending the legacy OBD1 ROM editor with scripts, ROM handlers, and plug-ins.

Warning

Always work on a copy of the ROM and verify every output before installing it in an ECU. API behavior can differ between Crome versions, and an incorrect script can corrupt tables, scalars, or checksums.

Accessing API Objects

Inside a Crome script, members of the default window object can be called directly or through window. An HTML-based Crome plug-in accesses the same objects through window.external.

// Direct access
refresh();
rom.byteAt(0x7FFF);

// Explicit window access
window.refresh();
window.rom.byteAt(0x7FFF);

// Plug-in access
window.external.refresh();

Object	Purpose
`window`	Dialogs, plug-in registration, external commands, and display refresh
`window.rom` / `rom`	Read and modify the active ROM, tables, scalars, and feature flags
`window.files` / `files`	Open, save, read, and write files

Window Functions

Function	Purpose
`addRomHandler(romtype, author, jscmd)`	Register a handler for a ROM type
`addPlugin(author, mnucaption, jscmd, category)`	Add an entry to Crome's plug-in menu
`alert(msg)`	Display a message with an OK button
`confirm(msg)`	Display a Yes/No confirmation; returns boolean
`DecToHex(dec)`	Convert a decimal value to a hexadecimal string
`exal(cipherstring)`	Evaluate an encoded JavaScript string
`GetFilePath(filename)`	Return the path portion of a filename
`GetFileName(filename)`	Return the name portion of a filename
`HiByte(w)`	Return the high byte of a word
`LoByte(w)`	Return the low byte of a word
`input(msg, options, values)`	Display an input selection dialog
`include(filename)`	Include another script file
`prompt(caption, msg, default)`	Prompt for a response
`select(prompt, selection)`	Return the selected item index, or `-1` when cancelled
`shell(filename, params, windowstate)`	Start an external application
`shelld(doscmd)`	Run a DOS command and return its output
`shellw(filename, params, windowstate)`	Start an application and wait for it to close
`showBrowser(url, width, height)`	Open Crome's built-in browser
`refresh()`	Refresh the editor after a script changes the active ROM

Note

The archived signature declares prompt() as returning a boolean, while its description suggests it returns the user's response or an empty string. Verify behavior in the specific Crome version being targeted.

ROM Object

Byte, Word, and Table Access

Member	Access	Purpose
`byteAt(addr)`	Read/Write	Get or set one byte at a ROM address
`wordAt(addr)`	Read/Write	Get or set a little-endian word at a ROM address
`working_table`	Read/Write	Select the active fuel or ignition table
`tableByte(col, row)`	Read/Write	Get or set a raw byte in the active table
`tableValue(col, row)`	Read/Write	Get or set the interpreted table value
`tableWidth`	Read-only	Width of the active table
`tableHeight`	Read-only	Height of the active table
`mapScalar(table, col)`	Read/Write	Get or set a MAP scalar in millibars
`revScalar(table, row)`	Read/Write	Get or set an RPM scalar

Working Table Values:

0: Low fuel
1: High fuel
2: Low ignition
3: High ignition

ROM Metadata and Feature Flags

Member	Access	Purpose
`addressOf(name)`	Read/Write	Address stored in a named special register
`addressIn(index)`	Read/Write	Address stored in special-register index `0`â`63`
`base`	Read/Write	Base ROM used for default address locations
`title`	Read/Write	Text shown in Crome's status bar
`filename`	Read-only	Full filename of the active ROM
`OBDMode`	Read/Write	Formula mode: `0` OBD0, `1` OBD1, `2` OBD2
`notes`	Read/Write	Notes attached to the active ROM
`gup()`	Function	Create a group undo point

Feature Flags (Read/Write Byte):

hasLaunchControl, hasFullThrottleShift, hasFinalMultiplier, hasShiftLight, hasIAB (Set to 1 to enable).
hasBoost: 0 none, 1 stock MAP, 2 3-bar, 3 custom.

Files Object

Member	Purpose
`showSave(filter, filterindex)`	Show save dialog; returns filename
`showOpen(filter, filterindex)`	Show open dialog; returns filename
`exists(filename)`	Return true if file exists
`getFile(filename)`	Read a text file
`putFile(filename, data)`	Write data to a file
`browseFolder`	Show folder browser; returns path

Special Register Names

Use these names with rom.addressOf('NAME') or their numeric index with rom.addressIn(index).

Name	Index	Purpose
`CHECKSUM`	0	Checksum correction address
`LOW_MAP_SCALAR`	1	Low MAP scalar address
`HIGH_MAP_SCALAR`	2	High MAP scalar address
`LOW_REV_SCALAR`	3	Low RPM scalar address
`HIGH_REV_SCALAR`	4	High RPM scalar address
`LOW_FUEL`	5	Low fuel table address
`HIGH_FUEL`	6	High fuel table address
`LOW_IGNITION`	7	Low ignition table address
`HIGH_IGNITION`	8	High ignition table address
`REVCUT1`	11	First rev-cut value address
`VTEC_TABLE`	15	VTEC table address
`IDLE`	25	Idle value address
`LAUNCH_CUT`	40	Launch-control cut value address
`SPEED_LIMIT`	44	Speed-limiter value address
`SL_RPM`	57	Shift-light RPM address

Applies to

8 taxonomy links

Cars 8 links

Acura

2 links

Model Integra

Generation 3rd Gen (DC2/DB8) 1994-2001 / DC2, DC4, DB7, DB8

Honda

6 links

Model Accord

Direct taxonomy match

Model Civic

Generation 5th Gen (EG) 1992-1995 / EG, EH, EJ

Model Integra

Generation 3rd Gen (DC/DB) 1994-2001 / DC1, DC2, DB6, DB7, DB8, DB9

Model Prelude

Direct taxonomy match

Accessing API Objects#

Window Functions#

ROM Object#

Byte, Word, and Table Access#

ROM Metadata and Feature Flags#

Files Object#

Special Register Names#