Stephen A. Lawrence wrote:
You could claim, of course, that Windows NT was a "rewrite" of the old Windows OS and so it isn't as old as it looks . . .
That is exactly what Brooks (and I) have in mind. You have to go back to square one and write the whole thing over again. That does not mean you abandon the outward appearance or the standards! You don't throw away all of the old product, by any means. You make a new version that is as backward compatible as possible, although compatibility hampers innovation.
I gather the operating system for Apple computers has been rewritten from scratch more often than Windows, and I have it is far more reliable and fast as a consequence.
I have heard that Apple is more ruthless about backward compatibility. Microsoft cannot afford to be, because if the new Windows does not work with old hardware, people will eventually throw away their hardware and buy a Mac!
. . . *and* NT was based in part on VMS, so it's got some very, very old code in it.
All software has algorithms (if not actual code) going back to the first programs in the 1950s. I meant that literally. I can spot it, because I go back pretty far myself, to 1965. Many computer algorithms, such as sorting and indexing systems (ISAM as it was first called) are based upon manual systems used before computers were invented to keep track of things such as paper cards in boxes. Much of the terminology used in computers such as "registers" and "FILO" record, and index go back to the pre-computer era. In fact you will find recognizable versions of some of these techniques in ancient Rome, China and Japan. Quoting a discussion of ISAM by N. Graham "Microprocessor Programming" (1977): "It is worth noting that the distributed free space technique is usually used for filing cabinets and library shelves to allow for expansion. Many exotic sounding computer techniques mimic common sense approaches that we all use every day." (Nowadays it is the other way around: people don't use paper files, and my daughters did not know what the "folder" icon resembles in the real world.)
These systems were invented and perfected in the 19th century, and used in giant insurance companies in the US and the UK, to process payments and issue claims, and during the U.S. Civil War in the War Department for filing and order entry operations. Early in the war the Department was in chaos, but when Stanton took over as Secretary, he saw to it that order for blankets or cartridges that arrived in the morning was processed and telegraphed to the manufacturer by close of business day. They processed millions of items with a small staff in a modest building next to the White House. I have seen descriptions of these manual systems and they were amazingly quick & efficient.
These operations were first automated for the 1890 census by Herman Hollerith, using punch cards. He later founded IBM. All computers are a direct derivative of his systems.
- Jed
