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DivMMC compatibility

Configure Spectranext before connecting DivMMC

By default, Spectranext does not expect a DivMMC device. On revision B boards, using both devices without enabling DivMMC compatibility can cause a dangerous bus conflict. Do not power them together until Spectranext is correctly configured.

Spectranext supports DivMMC, but compatibility must be enabled manually. You also need to install the SPX dot command on the DivMMC card so Spectranext can start each time you turn on or reset the Spectrum.

Enable DivMMC compatibility​

Setup has two parts: enable compatibility on Spectranext, then install SPX on your DivMMC card. You can also add a startup program to run it automatically. Enabling the setting is only half of the setup—Spectranext needs the SPX command to start. After the steps below, continue with Set up automatic startup, using the installer or the separate downloads.

  1. Start the Spectrum with Spectranext connected and DivMMC removed or disabled.

  2. Press the Spectranext Magic button to open its menu, then open Spectranext settings.

    Spectranext settings menu with DivMMC compatibility as option B

  3. Open DivMMC compatibility and select Enable DivMMC compatibility.

    DivMMC compatibility screen showing the warning and Enable option

  4. Read the warning and press Y to confirm.

  5. The Spectrum resets and Spectranext stops, showing a brief yellow LED flash with a long pause. Disconnect all power, including USB. Pressing reset is not enough.

  6. Install or enable DivMMC while the system is unpowered, then reconnect power.

Once compatibility is enabled, the system needs DivMMC to work. Follow the startup instructions below to finish setting up its card.

Normal firmware updates also update the bootloader automatically. There is no separate bootloader upgrade step.

Set up automatic startup​

In this mode, DivMMC starts first. Spectranext waits for the .spx command instead of starting automatically on its own. The command must be installed as /BIN/SPX on your DivMMC card.

To start Spectranext automatically, autoboot needs to run .spx after every startup and reset. This requires AutoBoot=3 in /SYS/CONFIG/ESXDOS.CFG and a suitable /SYS/AUTOBOOT.BAS program. There are two ways to set this up below.

Autoboot is optional. Without it, Spectranext stays completely out of the way, leaving you free to use DivMMC on its own. Whenever you want to use Spectranext, type .spx at the BASIC prompt. After a startup or reset, you will need to run .spx again before using Spectranext.

Use the installer​

Download SPXINST.TAP and copy it to your DivMMC card. With compatibility enabled, load the TAP through your DivMMC browser, or attach it with esxDOS and load it:

.tapein /SPXINST.TAP
LOAD ""

The installer asks how you want Spectranext to start:

SPX installer offering Spectranext only, Spectranext with launcher, or keeping the existing startup program

  • A — Spectranext only: replace AUTOBOOT.BAS with a program that runs .spx. This is the less intrusive option.
  • B — Spectranext and launcher: replace AUTOBOOT.BAS with a program that runs .spx, followed by %launcher.
  • C — Keep your startup program: leave AUTOBOOT.BAS unchanged. You must add .spx to it yourself before restarting.
  • X — Cancel: leave everything unchanged.

Choosing A, B, or C installs SPX and sets AutoBoot=3, keeping your other esxDOS settings. A and B replace your existing startup program, so choose C if you want to keep a custom one.

The installer saves any replaced files with a .BAK extension. If a backup from an earlier installation already exists, it asks you to move it elsewhere before trying again. Wait for the completion message, then disconnect all power, including USB, before reconnecting it. A reboot or reset is not enough. If you chose C, finish editing your startup program first.

Successful installation with a reminder to disconnect all power, including USB

The installer is intended for classic esxDOS 0.8.9.

Prepare the card on a computer​

  1. Download SPX and copy it to /BIN/SPX on the card.

  2. Open /SYS/CONFIG/ESXDOS.CFG in a text editor. Change the existing AutoBoot setting to:

    AutoBoot=3

    If the setting is missing, add it. Leave the other settings unchanged. This makes esxDOS load your startup program after both power-on and reset.

  3. Choose one of the ready-made startup programs below, rename the downloaded file to AUTOBOOT.BAS, and copy it to /SYS/AUTOBOOT.BAS. Keep a copy of your existing file before replacing it.

Start Spectranext only: download AUTOBOOT.BAS.

10 .spx

Start Spectranext and open the launcher: download AUTOBOOT.BAS.

10 .spx
20 %launcher

These downloads are ready-to-load Spectrum BASIC files, not text files. Copy them directly to the card. If you already have a custom AUTOBOOT.BAS, add .spx before any commands that use Spectranext instead of replacing the program.

What changes when using DivMMC?​

  • Startup comes from the DivMMC card. Without a working autoboot program, Spectranext will not start automatically. You can type .spx at the BASIC prompt to start it manually.
  • DivMMC keeps its own menu. A quick press of Spectranext's Magic button restarts the system instead of opening the Spectranext menu. Release while the LED flashes red to restart; holding longer starts the disable countdown.
  • The launcher remains available. After .spx has started Spectranext, type %launcher to open it, or use the launcher startup program above.
  • Spectranext debugging is unavailable in this mode.

See Status LED for the button and startup indications.

Disable DivMMC compatibility​

  1. Hold the Spectranext Magic button. It first flashes red, then flashes yellow increasingly quickly.
  2. Keep holding for ten seconds in total. Releasing while it flashes yellow cancels the action.
  3. When compatibility is disabled, the Spectrum resets and the LED changes to a brief yellow flash with a long pause.
  4. Disconnect all power, including USB.
  5. Remove or disable DivMMC before reconnecting power. Spectranext will then start normally without .spx.
Remove or disable DivMMC before the next startup

After this sequence, Spectranext no longer expects DivMMC. DivMMC must be removed or disabled before you power the system again. On revision B boards, leaving it active can cause a dangerous bus conflict. Check that DivMMC is removed or disabled before reconnecting any power.

You can leave SPX and the startup files on the card for future use, but they do not make it safe to reconnect an active DivMMC while compatibility is disabled.