The Solidity Language
Æternity has limited support for the Solidity language bytecode and ABI. There are a number of test cases and some scaffolding code. However, it is not mature enough to be part of consensus and thus the Solidity ABI is not allowed on chain.
For a full description of Solidity see The Solidity Specification.
The Solidity_01 ABI
Note that the Solidity_01 ABI specifies that the create contract initial call returns the actual bytecode to be stored in the contract state tree to be used for future calls.
Storing the contract state
Contracts store the VM storage map containing 256 bit binaries for both keys and values in the MPT. Undefined keys are treated as having the value 0 and keys bound to the value zero are stored as the empty binary, thus purging them from the tree.