Odroid-Go Spectrum Emulator
Features
	•	Emulates 48K ZX Spectrum. Runs at 100% speed, 256x192 screen,border,sound emulated.
	•	load/save SNA and Z80 snapshot files
	•	re-map buttons to spectrum keys, standard options available e.g. cursor keys
	•	on-screen keyboard to simulate hunt-and-peck typing.
	•	fast startup (about 1 second), resume from last saved position.
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Installing
This assumes you have already built the ODROID-GO and set up an SD card to run the default emulators.
Note that installing this emulator replaces the existing ones, but they can be restored later.
1) Download the file ZX_Spectrum.fw from here and put it in the ordoid/firmware directory of your SD card. You probably also should make sure there is a file Go-Play.fw here so you can go back to the existing emulators.
Go-Play.fw can be found at: https://github.com/OtherCrashOverride/go-play/releases/

2) While you have the SD card out of the ODROID, make a new directory /roms/spectrum on the card and copy your snapshot files (SNA or Z80) in here. Using subdirectories is fine.

3) Switch off ORDOID-GO, hold down 'B' button and switch back on, keep B button pressed for 5 seconds. If nothing happens you need to update the bootloader - see
https://forum.odroid.com/viewtopic.php?f=158&t=31513
Go to the 'ZX Spectrum' option and press the 'start' button to flash the firmware.
To go back to the existing emulators, follow step 3) again, but choose Go-Play instead.
(NOTE - if you get a "BOOT SET ERROR" doing this, do the Go-Play install a second time)
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Tips
	•	in the on-screen keyboard, the Select and Start buttons are mapped to Caps Shift and Symbol Shift, if upper-case or punctuation characters required. 'B' exits. 
	•	in the file browser, left/right goes back/forward a page of files for large directories. 'B' goes up a directory. 

Known bugs
	•	wont load 16Kb SNA snapshots (these are files <16Kb in size, '3D Death Chase' and 'Jetpac' being notable examples.). Convert them to regular 48K snapshots in another emulator to load them. 
	•	At the moment it doesn't store a set of button mappings per game, just a single set that is restored at power-on. Per-game button mapping memory possible though. 
	•	It will try to load TAP and TXZ files, but wont work with them. Don't use these file types, OK? 
Technical Information
	•	based on the Spectemu emulator. Chosen as it already supports a 320x240 pixel screen.
https://sourceforge.net/projects/spectemu/files/spectemu-stable/

Mapping Controls
	•	Store a set of button mappings per game. For a game [gamename].z80 the button mappings are stored in [gamename].map