On 2017-10-13 15:11, alister <alister.w...@ntlworld.com> wrote:
> On Sat, 14 Oct 2017 01:48:44 +1300, Gregory Ewing wrote:
>> Steve D'Aprano wrote:
>>> I wasn't questioning where the data came from, but how the compiler can
>>> write to READ ONLY MEMORY which might not even be in the same continent
>>> as the compiler that generated the code.
>>
>> I thought it would be fairly obvious that by "put it in read-only
>> memory" I meant "arrange for it to be in a location that is read-only at
>> run time". Obviously it can't be read-only at *compile* time, just as a
>> physical ROM can't be read-only at manufacture time.
>
> oh yes it can
> in the past for large quantitys the data in a ROM chip was part of the
> chip etching mask (unless you consider a blank silicon wafer to be
> "Programmable" by the etching process)rather than prom which used
> programmable fuses or prom which could be erased by UV light (assuming
> the chip was fitted with a window otherwise it was known as one time
> programmable EPROM)
He didn't say "programmable". He said that the is "not read-only".
Obviously the wafer is modified during the etching process and
afterwards it contains information it didn't before. Would you say a
piece of paper is "read-only" because you can't program it using address
and data lines? I can write on it, I just need a different tool.
hp
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