> They were not "minor" changes. For example, the S/360 used core memory. How much more memory (and hardware changes) would have been required to implement 32-bit memory as opposed to the 24-bit memory?
For instance, from the 360-91 functional characteristics, the processor storage capabilities, the system could only have 2MB of main storage, and 4MB of extended storage.
In 1960's memory was approximately $2.6 million per megabyte. So, a fully loaded 360-91 with 6 megabytes of storage was north of $12 million in 1960 dollars.
According to the inflation calculator, $1 in 1960 buys the same as $10 today. So, the same computer in todays dollars was $120 million! And IBM spent $5 billion in 1960 dollars to develop the 360...
Joe