I thought a special size picture of the insides was warranted.
Quite a few things to note here. There are two banks of RAM, one of which is unfilled on the 512 model. Next to the RAM is the first of two batteries, the other being the more noticeable Varta mempack type near the ROMs, of which there are 4. There isn't space for any additional sideways ROMs, so the MOS ROM must have been thought to be comprehensive for Communicator users' needs. That or it was possible like in RISC OS to load modules into the RAM.
There are connectors to take a Master type Econet module, and I wonder if the set of links next to the second battery might be Econet station number links, although why they - or anything else - would be numbered 2 to 9 is anybody's guess.
There's no SAA5050 Teletext chip and, although I didn't get a screenshot, the Teletext screen mode wasn't pure BBC Mode 7 - it reminded me very much of the typeface used to display Ceefax in 1990s television sets - close, but not near enough to fool a BeebMaster.
The CPU is the 65C816, a hybrid CPU able to operate in 8-bit 6502 emulation mode and its own 16-bit mode, making the Communicator the only 16-bit Acorn every made. I don't know whether it uses its emulation mode to run the modules in ROM, or whether they were all re-written for the 16-bit capability of the processor.