glitch
Veteran Member
I FINALLY FINISHED MY PROTOTYPE! Started it in 2010:
Implemented as a wire wrapped prototype, there are already some things I plan on changing though!
Full writeup: http://www.glitchwrks.com/2016/03/29/ferroelectric-ram-part-1
So, basically, FeRAM is core on silicon. Tiny bits of magnetic material on silicon, completely nonvolatile, even destructive readout! I ordered samples from Ramtron (before Cypress bought them) and started using some of their serial FeRAM devices in modern microcontroller projects. I've had the parallel FM18W08 samples since 2010, and intended to build a S-100 board using them, but it's taken me this long to get there. I still haven't found the prototype schematics (stuck somewhere unexpected in the process of moving, probably), so finishing up the board required making some guesses on what I was originally trying to do. It works! The write inhibit circuitry was the last bit needed to make it usable -- before you had to manually hold the computer in reset during power up and power down, and even then you'd sometimes get corrupted memory.
Since I don't have my original schematic, I decided not to implement a few functions (mostly just PROT and UNPROT functionality, as described in my writeup). I'm planning on doing another revision and then a production board.
What's it good for? Basically you can use it just like core on a minicomputer. You can do front panel development without much risk of losing your work on power down. You can load monitors/bootstraps/whatever into RAM on one system, pull the board, and plug it into another S-100 system you're bringing up. You can load BASIC into your Altair 8800 from teletype, and not have to do it all over again when you power off. Nonvolatile characteristics aside, it's also a zero wait state low-power static RAM board.
The write inhibit circuit can also force the system into reset, if so jumpered, and supply /PWRFAIL on pin 13 of the bus, which is defined in IEEE-696. The board follows IEEE-696 signal specs for 8-bit systems. Not 16-bit capable at the moment, but a production version might include that functionality. It's also a fine static RAM board if you plug in some 62256 32K x 8 SRAMs and jumper over the write inhibit circuit.
Planned functionality includes monitoring the 8V rail instead of the 5V line after the local regulator, and support for protecting blocks of memory using either the PROT/UNPROT front panel switches or output to an I/O port.
Anyone interested in this?
Implemented as a wire wrapped prototype, there are already some things I plan on changing though!
Full writeup: http://www.glitchwrks.com/2016/03/29/ferroelectric-ram-part-1
So, basically, FeRAM is core on silicon. Tiny bits of magnetic material on silicon, completely nonvolatile, even destructive readout! I ordered samples from Ramtron (before Cypress bought them) and started using some of their serial FeRAM devices in modern microcontroller projects. I've had the parallel FM18W08 samples since 2010, and intended to build a S-100 board using them, but it's taken me this long to get there. I still haven't found the prototype schematics (stuck somewhere unexpected in the process of moving, probably), so finishing up the board required making some guesses on what I was originally trying to do. It works! The write inhibit circuitry was the last bit needed to make it usable -- before you had to manually hold the computer in reset during power up and power down, and even then you'd sometimes get corrupted memory.
Since I don't have my original schematic, I decided not to implement a few functions (mostly just PROT and UNPROT functionality, as described in my writeup). I'm planning on doing another revision and then a production board.
What's it good for? Basically you can use it just like core on a minicomputer. You can do front panel development without much risk of losing your work on power down. You can load monitors/bootstraps/whatever into RAM on one system, pull the board, and plug it into another S-100 system you're bringing up. You can load BASIC into your Altair 8800 from teletype, and not have to do it all over again when you power off. Nonvolatile characteristics aside, it's also a zero wait state low-power static RAM board.
The write inhibit circuit can also force the system into reset, if so jumpered, and supply /PWRFAIL on pin 13 of the bus, which is defined in IEEE-696. The board follows IEEE-696 signal specs for 8-bit systems. Not 16-bit capable at the moment, but a production version might include that functionality. It's also a fine static RAM board if you plug in some 62256 32K x 8 SRAMs and jumper over the write inhibit circuit.
Planned functionality includes monitoring the 8V rail instead of the 5V line after the local regulator, and support for protecting blocks of memory using either the PROT/UNPROT front panel switches or output to an I/O port.
Anyone interested in this?