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Infinite Array Abstraction

Memory works like an infinitely long, one-dimensional, byte array, a, initialized as:

ai∈[0,L-1] ← ith byte of an L-byte initial memory state

ai∈[L,∞) ← 0

Each MC instruction, f x, where f is an n-byte function, modifies n consecutive bytes, starting at index x:

ax‥ax+n−1 ← f(ax‥ax+n−1)

The computing machines of the next section employ this abstraction to satisfy their data storage needs. The text describes the array as if it oriented horizontally, starting with index 0 at the “left” end, and heading “rightward” toward infinity.