Manufacturer: IBM Memory technology: magnetic core First introduced: 1963 Memory size: 32K 36-bit words CPU technology: transistor Cycle time: 2 microseconds (0.5 MHz)

from Gordon Bell, 10/26/2000, see web site BTW: the IBM 7090 core was in oil. Not sure about Stretch, but it probably was too as it pioneered technology that the 7090 exploited. Ah Yes, the early magnetic core material was quite temperature sensitive. The magnetic characteristics changed quite a bit with temperature, and magnetic flipping used energy and warmed them up. I guess the oil helped stabilize their temperature. I remember magazine articles about the major efforts to find less temperature sensitive core material - which would eliminate the maintenance nightmare of having the core stacks in a tub of oil. Later core stacks (after about 1960) had the cores in air. :-)) A machine I worked on in 1960 had core stacks in air, but the core drivers had temperature sensors to adjust their current with the air temperature. Yes, the good old days were "interesting".

from Coslet, Tim July 2004

I've done a bit of research and found that both the 7090 and Stretch did use the same core memory unit: IBM 7302 - IBM 7030 Core Storage (16384 - 72-bit words: 64 data bits & 8 ECC bits) IBM 7302 - IBM 7090 Core Storage (32768 - 36-bit words) It was probably a different model with some different logic (as Stretch used 8 bits of each 72 for ECC and the 7090 used all the bits as data), but it would have been the same core, the same heated oil bath, the same cabinet, etc.