<altering the computer (machine) is that there is a definite distinction <between the circuitry to drive the logic unit (CPU) and the circuitry <which defines the stored program (code). So while a masked ROM cannot b <altered, you can swap out the ROM with a new ROM with a completely <different set of instructions, while the rest of the circuitry which <executes the code remains unmodified. Apply that to the 8048 or other single chip mcu. <digital computers and not analogue. I think the murky area being argued <here is strictly pertaining to analog computers since it is indeed a <series of filters and amplifiers combined to manipulate analog signals. <digital computer is something quite different, and I think quite easy to <define. Thats the point. Many exceedingly simple looking analogue systems perform what would take a fairly complex digital system to simulate.