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May20-07, 10:12 AM
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Quote Quote by Jeff Reid View Post
Regarding memory sizes on mainframes, high end IBM 360's and 370's had 1MB or more of memory during the 1960's and 1970's. By 1985, a Cray 2 super computer had 512MB of memory.
The IBM 360 was constrained to a max of 64k memory.
In the company I worked for, we had 5 370's, the biggest was 512k until 78 when they upgraded to a meg.
I think they did it to support TCAM the predecessor to VTAM.
The IBM 370 was constrained to 268 meg until around 84 when they came out with XA.
That was a PITA due to all the software that had used the upper 4 bits of the address to pass flags.