Famous reverse engineer and computing historian Ken Shirriff has put a considerably uncommon machine beneath the microscope for inspection: a ferroelectric random-access reminiscence (FRAM) chip, manufactured in 1999 and holding simply 8kB.
“The historical past of ferroelectric reminiscence dates again to the early Fifties,” Shirriff explains. “Many corporations labored on FRAM from the Fifties to the Seventies, together with Bell Labs, IBM, RCA, and Ford. Sadly, ferroelectric reminiscence had many issues, limiting it to specialised purposes, and growth was largely deserted by the Seventies. Ferroelectric reminiscence had a second probability, although. A serious proponent of ferroelectric reminiscence was George Rohrer, who began engaged on ferroelectric reminiscence in 1968. He shaped a reminiscence firm, Technovation, which was unsuccessful, after which co-founded Ramtron in 1984.”
The most recent tech to get the Shirriff teardown remedy is a ferroelectric RAM (FRAM) chip from 1999. (📷: Ken Shirriff)
It is a Ramtron half, produced in 1999, that Shirrif has investigated: a 64-kilobit, eight kilobyte chip that provides significantly increased longevity by way of each write-erase cycles and unpowered reminiscence retention than even trendy non-FRAM equivalents — one of many key causes the know-how hasn’t been fully deserted, regardless of complexities and bills in its manufacturing.
Shirriff’s evaluation of the de-capped FRRAM chip identifies 4 blocks of reminiscence parts, surrounded by decoders and sensor amplifiers and separated by plate line drivers. Additional investigation, and elimination of some reminiscence cells, unveils the weird format of a FRAM {hardware}: a three-dimensional construction that features cubes of zirconate titanate, a cloth made up of lead, zirconium, titanium, and oxygen. These cubes react to electrical fields, with the metals transferring inside a crystal lattice — flipping the bit in a means that is still steady even after many years with out energy.
Whereas the know-how affords glorious longevity, it is advanced and costly to fabricate. (📷: Ken Shirriff)
“FRAM reminiscence will ultimately put on out,” Shirriff admits, “however it may be written trillions of occasions, way more than flash or EEPROM [Electrically Erasable Programmable Read-Only Memory] reminiscence. The reminiscence is organized as 256 capacitors horizontally by 512 capacitors vertically, for a complete of 64 kilobits (since every bit requires two capacitors). The reminiscence is accessed as 8,192 bytes.”
Shirriff’s full write-up is offered on his web site, Righto.com.