Dec 24, 2023, 01:14 PM
https://www.tomshardware.com/pc-componen...hire-chip-
discovered-on-a-humble-floppy-drive-pcb
AS a XMAS Miracle
As 1977 back to the future
Transparent processor found in vintage HP computer – exotic silicon-on-sapphire chip discovered on a humble floppy drive PCB
A mysterious transparent chip has been found in an HP computer, dating back to 1977. Investigations have concluded that the custom chip was formed on a sapphire substrate, making it a silicon-on-sapphire IC. What was it for? Its function was far more mundane than you might expect: It was a support component on a floppy disk controller.
Computer historian and IC reverse-engineering enthusiast Ken Shirriff uncovered this interesting chip by de-capping a broken interface chip in a vintage HP computer. But the interface wasn’t from some futuristic photonic supercomputer server experiment from the company; it was in a humble floppy drive controller PCB sitting between HP's interface bus (HP-IB) and a Z80 processor.
Shirriff explains that the silicon-on-sapphire IC was found beneath the cap of a chip called the PHI (Processor-to-HP-IB Interface) and was used in multiple HP products back in the day. “It handles the bus protocol and buffered data between the interface bus and a device's microprocessor,” according to historians' investigations.
Silicon-on-sapphire may sound somewhat futuristic, but Shirriff’s blog highlights that ICs made this way have been around since 1963 or earlier. A notable example of a silicon-on-sapphire IC is the RCA 1802 processor used on the Galileo space probe that studied Jupiter and its moons.
discovered-on-a-humble-floppy-drive-pcb
AS a XMAS Miracle
As 1977 back to the future
Transparent processor found in vintage HP computer – exotic silicon-on-sapphire chip discovered on a humble floppy drive PCB
A mysterious transparent chip has been found in an HP computer, dating back to 1977. Investigations have concluded that the custom chip was formed on a sapphire substrate, making it a silicon-on-sapphire IC. What was it for? Its function was far more mundane than you might expect: It was a support component on a floppy disk controller.
Computer historian and IC reverse-engineering enthusiast Ken Shirriff uncovered this interesting chip by de-capping a broken interface chip in a vintage HP computer. But the interface wasn’t from some futuristic photonic supercomputer server experiment from the company; it was in a humble floppy drive controller PCB sitting between HP's interface bus (HP-IB) and a Z80 processor.
Shirriff explains that the silicon-on-sapphire IC was found beneath the cap of a chip called the PHI (Processor-to-HP-IB Interface) and was used in multiple HP products back in the day. “It handles the bus protocol and buffered data between the interface bus and a device's microprocessor,” according to historians' investigations.
Silicon-on-sapphire may sound somewhat futuristic, but Shirriff’s blog highlights that ICs made this way have been around since 1963 or earlier. A notable example of a silicon-on-sapphire IC is the RCA 1802 processor used on the Galileo space probe that studied Jupiter and its moons.
Thanks @zehq for ranks!!!