Introduced in June 1960 the IBM 7070 was a "transistorized IBM 650" utilizing core memory in place of the much slower drum memory used in the older vacuum tube 650's. The 7070 was the first transistorized machine. Due to incompatibilities with its tube based ancestors there was little incentive for most unit record customers to upgrade.
What made this series so unusual was the fact that the 707x's used the ten digit word length. This decimal architecture systems was based on storing two decimal digits in a 10 bit word using the two-out-of-five encoding system. The and non-Decimal Architecture members of the IBM 700/7000 series used BDC (binary-coded decimal) until replaced with 8-bit EBCDIC with the introduction of System/360.
Introduced in November 1961 the IBM 7074 was adopted by the U.S. Internal Revenue Service and several were put in service in 1962.
The IBM 7072 was introduced in November 1962 and was eventually replaced along with most of the 7000 series computers by System/360s in the mid to late 60's.
Access time - 6 microseconds (7070/7072), 4 microseconds (7074)
Add time - 72 microseconds (7070), 12 microseconds (7072), 10 microseconds (7074)
If anyone has more information about this unusual 10 bit core stack, please contact me. Bob@IBMcollectables.com