I last used one of these in 2018 to work on a historical project involving the MC6809 microprocessor. Prior to this I used one in 2012 to emulate code for the 6502 processor as part of my MacLAB reverse engineering. Back in my professional days, I used them to develop code for 8751 microcontroller projects.
Back around 1992, a company called "Grammar Engine Inc." produced a series of products, one of which was the "promice" ROM emulator. What this is is a little box with a serial cable on one side, and a cable you plug into a ROM socket on the other. Inside the box is some static RAM and a microcontroller. When you have some could you would otherwise burn into a ROM, you send it over the serial port, the microcontroller in the box loads your code into the "emulation RAM" and then makes it available via the cable (plugged into the ROM socket of a target system) so that the target system thinks it is an EPROM.
It works like a charm, and is almost a million times better than burning and erasing eproms. Once code is debugged, you do of course want to burn it into an eprom (or flash memory these days).
Tom's Computer Info / [email protected]