Amstrad ZX Spectrum +3

IICMEM is a 8kB memory (EEPROM) connected to the AY-3-8912 chip, that works as I²C controller. Used as a "disk" under ZXVGS to store files.

PL3FIX is a through interface that allows to connect interfaces without a need to make internal changes.

TI-of-TTL is a Timex Interface M-397 replacer, build from TTL chips only. Apart from TOS (upgraded to work with ZX128, too) in the extended memory there is ZXVGS and also keyboard test code.

TR-DOS traps are needed to run TR-DOS software under ZXVGS.

TRETRAP - wizardly connected EPROM, has also patches to allow fast loading of "*.TAP" files.
TRITRAP - mounted inside.
TRXTRAP - external interface.

YABUS.PL3 is an internal YABUS slot that allows to connect hard disk. The HDD replaces the 3" floppy disk drive.

YAMOD.ATBUS is the IDE multiplexer that interfaces the hard disk or CDD.

Z80JOY is the Kempston Joystick interface mounted under Z80 chip. The extension board can be soldered over the Z80 chip. Or the Z80 chip can be desoldered, replaced with a GOLD socket, then interface goes into socket and the Z80 chip into it. As the output can be used one of original joystick slot or extra slot somewhere on the case.

ZX+3.5 means the 3.5" FDD mounted in place of the 3" one.

ZXVGSPL3 means memory upgrade from 64kB PROM into 32kB SRAM and 32kB EPROM and ZXVGS installation. This upgrade can be also done with an external PL3MEM interface.