## Chapter 21 – Optional Features ### Overview Depending on the model you have and the Kickstarter you participated in, your ZX Spectrum Next may have one of two types of mainboards; Issue 2 or Issue 4 (See appropriate figures in the beginning of this Chapter). If you have an Issue 2, the rest of the chapter is for you, as many of the standard features on an Issue 4, used to be optional on the Issue 2. These are: *RTC* hardware, a WiFi module (*ESP*), extra RAM and the *Raspberry Pi Zero* (*RPi0*) accelerator. If on the other hand, you have an Issue 4, the only feature you may be interested in is the Raspberry Pi Zero accelerator. The following sections will describe how to install and use them. Remember that modifying your ZX Spectrum Next carries a number of risks and that if you are not careful, you can damage your machine! > **Notes** > > ⚠ > > Before you proceed, please make sure that: > > **A.** You're comfortable with tools and at least somewhat dexterous with a soldering iron\ > **B.** You understand the dangers of Electrostatic Discharge and sensitive components\ > **C.** You have enough patience –and finally–\ > **D.** You have downloaded and installed the latest System/Next™ distribution ### Installation (for Issue 2 mainboards) Most add-ons are very easy to install with the exception of the *Real Time Clock* module and *RPi0 accelerator*. Installation of the former, requires soldering a number of parts onto the board and should be undertaken only by users with soldering experience. We recommend using a specialised service, if you do not feel comfortable with a soldering iron. Installation of the latter also requires soldering experience but that's confined on the RPi0 board itself and not on the ZX Spectrum Next. On the table below, we list all parts that you will need to perform each upgrade: | Option | Parts Needed | Notes | |---|---|---| | 1024K Memory upgrade | 2 x Alliance AS7C34096A-10JCN –or–
2 x Samsung K6R4008V1D-JI10 | Upgrades the memory to 2048K | | RTC module | 1 x DS1307 IC
1 x YXC YT-38, 32.768KHZ, 12pF oscillator or similar
1 x CR2032 Battery holder
1 x CR2032 Battery 3.3V
1 x 8 pin DIL socket (optional) | Allows time and date keeping that does not rely on your computer being powered on | | WiFi module | ESP8266 ESP-01 | Provides access to the internet and your home network | | RPi Accelerator | 1 x Raspberry Pi Zero
1 x Female IDC connector 2 x 20 pins | Various functions such as enhanced audio | Installing a WiFi module, only requires you to populate the empty socket marked by a **B** on the diagram (page 218) by plugging in the *ESP* module in the place reserved. Memory is equally simple, however, care must be exercised in that the RAM sockets accept larger chips than the ones the ZX Spectrum Next has. You need to line up the orientation notch (**B**) of each RAM chip (**A**) with the corner of the socket (**D**) leaving space (**C**) in the back of the socket. Once you have everything lined up, push with your finger at the centre of the RAM chip and it should make a slight click. While pushing the RAM in (and