Board Updates

Since the launch of the Spectra interface, a number of improvements have been made to make it more robust, compatible with other devices and to introduce new functionality. This page lists all such modifications. If you are unsure whether your boards requires any of these modifications then email me and I can advise you.

Pull Down Resistors

For improved compatibility with devices connected behind Spectra, resistor R14 has been changed to 2k2. For improved reliability using ROM cartridges, resistor R12 has also been changed to 2k2. It is desirable to make these modifications, although it is only necessary to do so if compatibility issues are encountered. All boards produced since April 2015 have had 2k2 resistors fitted as standard.

Protection Diode

To provide protection to the main IC on the board, an additional diode has been introduced. It neatly fits on the underside of the board between two existing contacts and hence there is no need to cut cuts or add wire links. It is recommended to make this modification. All boards produced since February 2017 have had the diode fitted as standard. The diode is of type SR104 (Schottky, 40V, 1A) should you wish to fit one yourself. Note that it is the anode of the diode that connects at the contact of the edge connector, as shown in the following photo of the Spectra+128 board:

Spectra Interface Protection Diode

If your Spectra or Spectra+128 board does not have the diode fitted and you have the capability to solder one in place then contact me and I can post a diode to you.


Spectra CPLD Logic

The final release of the CPLD logic (version 1.07) for the original Spectra interface shipped with all boards produced from July 2014 onwards.

Updating the logic requires the use of a JTAG programmer, with a custom adapter constructed to fit the following holes on the Spectra board:

Spectra Interface JTAG Connection

The CPLD is a Xilinx XC95216-10PQ160C. To reprogram it, you need to plug Spectra into your Spectrum without any other peripherals connected and power it on. Then you should first erase the CPLD and then program in the new logic. You should only attempt to reprogram the logic if you are experienced in programming CPLDs.

Click here to download the Spectra JED logic file V1.07 text file.

Note that this version of logic will not work with a Spectra board that has been upgraded to the Spectra+128 configuration.


Spectra+128 CPLD Logic

Spectra+128 CPLD logic began with version 1.08, with the final release being version 1.09 and shipping with all boards produced from June 2015 onwards.

Click here to download the Spectra+128 JED logic file V1.09 text file.

Note that this version of logic will not work with the original Spectra board for the Spectrum 48K. Upgrading a Spectra board to the Spectra+128 configuration also requires replacement of several components, the addition of a couple of new components, some tracks cut and a few wire links fitted. The complexity of the update means that boards must be returned to me to be upgraded. There is a small fee for upgrading a board to cover the cost of the new components. Please email me if you wish to have your Spectra board updated to the Spectra+128 configuration.