Welcome to JD Micro!

Home of ROMX and RAMX products for the Apple II series (][, ][+, //e, IIc, IIc+)

ROMX is an in-system programmable device that replaces the system ROM chip(s) in your Apple II/II+, IIc, IIc+ or IIe computer. ROMX will store up to 15 ROM images, and present them for selection via an on-screen menu that is displayed at power up. In addition, the menu system itself (the ROMX firmware) is updateable in-system.

Being in-system programmable means that you can re-program ROMX with your own ROM images without removing the device from your computer, and without need for an external programmer. Uploading of new ROM images is done through either the ROMX menu, or by running the ROMX.DISK utility from the ROMX floppy disk image. The firmware is also upgradeable using the same process.

A ROM image doesn't have to be a system ROM! We've ROMified DOS images as well as games and utilities. Linking a System ROM image to a DOS image means you can boot DOS instantly. ROMified games also load instantly. There are also a number of diagnostic ROM images available.

There are currently five different versions of ROMX available :

ROMX (Apple II/II+)

ROMX+ (Apple II/II+)

ROMXc (Apple IIc)

ROMXc+ (Apple IIc Plus)

ROMXe (Apple IIe)

ROMX+, ROMXc, ROMXc+ and ROMXe have an on-board real-time clock with battery backup. A custom clock driver has been built into ProDOS - boot ProDOS instantly, with support for the real-time clock.

All ROMX variants features a ROM-Link interface that connects the ROMX board to an optional ROMX text/video ROM module. The text/video ROM contains multiple different fonts, with the ROM-Link interface allowing you to switch text/video ROMs from the ROMX menu or to associate a font with a specific ROM image. Note that the text/video ROM module is not in-system programmable, however we can share the programming adapter PCB design such that you can reprogram it in an EPROM programmer if you would like to customise the font selection.

ROMX also has recovery mode - if a firmware update should fail for any reason (power outage etc), then you can pull the recovery jumper and boot into a special recovery menu. From the recovery menu you can select a ROM image to boot, then re-flash the firmware. The recovery image also features a basic RAM test and will beep out an error code to identify faulty RAM chips - super handy for flaky Apple || plus systems when trying to get the machine up and running for the first time (in a long time).

ROMX for Apple II/II+ is shown above, along with its 2316B SPCL text ROM which is preloaded with 16 fonts. A 2513 version of the text ROM is also available for pre Rev 7 motherboards.

About ROMX / JD Micro

ROMX is the result of a collaboration between Dean Claxton in Australia and Jeff Mazur in the USA. In May 2020, Dean put together a tiny ROM replacement board that utilised a flash memory chip rather than an EEPROM, and posted images of the board on the Applefritter forum. Jeff commented that In-System Programmability should be possible - a CPLD was slung underneath, Jeff perfected the Apple software including the menu system and programming algorithms whilst Dean layed out the PCBs and programmed the CPLD. ROMX was born! The collaboration between Jeff and Dean was formally named JD Micro in 2021.