TG16:FRAM/FeRAM Mod

With the introduction of the PC Engine CD in 1988, NEC also introduced a way for people to save their games due to the read-only nature of CD-ROM media and the lack of any save methods for HuCards at the time. This was accomplished by using a 2 KB SRAM (static RAM) chip backed by a 0.47F supercapacitor, which is charged by the system's 5V rail and provides power to the SRAM chip even when the system is powered off. This method has a significant flaw in that if the system is not powered on within two to three weeks, the supercapacitor will lose charge and all saves will be lost. Thankfully this can be rectified by replacing the original SRAM chip with a modern FRAM chip, which can retain data for decades without needing a power source.

=Materials required=
 * 4.5 mm gamebit screwdriver (for most systems)
 * T10 security screwdriver (for Japanese Duo consoles and Super CD-ROM2)
 * Phillips head screwdriver
 * FM16W08 FRAM chip
 * Temperature-controlled soldering iron (preferably with a J-hook tip)
 * Hot air station
 * Kapton tape and/or aluminum foil
 * Leaded solder
 * Flux
 * Desoldering braid
 * Multimeter
 * Magnet wire (for systems where an adapter PCB is not available)

=Installation= The principles behind the FRAM mod remain the same for all PC Engine/TurboGrafx-16 systems which have memory backup, but the method varies significantly between them.

PC Engine Duo/TurboDuo

 * 1) Flip the console over and unscrew the five security screws (4.5 mm gamebit screws on the TurboDuo, T10 security screws on the PCE Duo), then remove the top case.
 * 2) Remove the screws holding the motherboard down to the bottom case and disconnect the CD drive and power jack. Unsolder the two ground wires from the CD drive, there is one connected to the bottom RF shielding and another on the right-hand edge of the motherboard. If you have a TurboDuo, you will also need to remove the top RF shield which covers most of the internals.
 * 3) With the motherboard removed, locate the save RAM chip. It is a Sanyo LC3517BML-15 chip located immediately to the right of the right-hand heat sink.
 * 4) Place Kapton tape or tin foil around the components in the vicinity of the SRAM chip so that they will not be damaged or accidentally removed during the removal process.
 * 5) Set your hot air station for low to medium airflow and set the temperature for around 335 degrees Celsius.  Hold the nozzle within an inch of the chip and swirl it around so that the heat is applied evenly. After about 10-15 seconds, the SRAM chip should become loose. Carefully remove it from the board and set it aside. Do not force it or make any fast movements as you could damage or lift pads.
 * 6) Clean the pads by applying flux and then carefully and lightly dragging desoldering braid over them. Once the old solder has been removed, clean off the area with IPA or flux remover.
 * 7) To simplify the installation of the FRAM chip, PC Engine developer David Shadoff has designed a flex PCB which sits over the pads for the SRAM chip and reroutes these pads to the appropriate pins on the FRAM chip.

Duo-R/Duo-RX

 * 1) Flip the console over and unscrew the five security screws (T10 security screws). Carefully pull off the top case as the CD door pinswitch is connected to the motherboard on the right-hand side. Remove the connector for the pinswitch and you can now set the top case aside.
 * 2) Remove the screws holding the motherboard down to the bottom case and disconnect the CD drive. Set the CD drive aside and you can now remove the motherboard.
 * 3) With the motherboard removed, locate the save RAM chip. It is located on the underside of the motherboard towards the front left-hand edge and labeled IC512.
 * 4) Place Kapton tape or tin foil around the components in the vicinity of the SRAM chip so that they will not be damaged or accidentally removed during the removal process.
 * 5) Set your hot air station for low to medium airflow and set the temperature for around 335 degrees Celsius.  Hold the nozzle within an inch of the chip and swirl it around so that the heat is applied evenly. This may take a while as the SRAM chip is secured by small blobs of epoxy to the motherboard, not unlike certain Sega Saturn board revisions. After about 15-20 seconds, the SRAM chip should become loose. Carefully remove it from the board and set it aside. Do not force it or make any fast movements as you could damage or lift pads or traces.
 * 6) Clean the pads by applying flux and then carefully and lightly dragging desoldering braid over them. Once the old solder has been removed, clean off the area with IPA or flux remover.
 * 7) Although designed for the original Duo, David Shadoff's flex PCB also works with the Duo-R.

IFU-30A

 * 1) Flip the interface over and unscrew only the three long 4.5 mm gamebit screws toward the back. You do not need to take out all the screws as the internals are all inside the rear gray section. Carefully undo the three tabs holding the gray section together and manipulate the eject lever so that it can be worked free. Make sure to remove the connector for the power LED before completely separating the two halves.
 * 2) Remove the two screws near the CD drive connector and disconnect the power switch and AV/power jack block on the left-hand side. Lift up the board and then unscrew the ground lug connecting the SRAM board shielding to the bottom RF shield.
 * 3) With the motherboard removed, carefully and slowly remove the SRAM board that sits near the PC Engine connector. This PCB is attached by several dense connectors around its perimeter so make sure to go around and loosen each one before taking the board off.
 * 4) With the SRAM board removed, locate the save RAM chip. It should be located right next to the green supercapacitor that powers it.
 * 5) Place Kapton tape or tin foil around the components in the vicinity of the SRAM chip so that they will not be damaged or accidentally removed during the removal process.
 * 6) Set your hot air station for low to medium airflow and set the temperature for around 335 degrees Celsius.  Hold the nozzle within an inch of the chip and swirl it around so that the heat is applied evenly. After about 10-15 seconds, the SRAM chip should become loose. Carefully remove it from the board and set it aside. Do not force it or make any fast movements as you could damage or lift pads.
 * 7) Clean the pads by applying flux and then carefully and lightly dragging desoldering braid over them. Once the old solder has been removed, clean off the area with IPA or flux remover.
 * 8) Take your FRAM chip and prepare it for installation. You will need to lift up five pins on it before it can be soldered to the board. This is because the FM16W08's pinout doesn't quite line up with the original SRAM chip. This includes the 5V and write enable pins which are crucial to the chip functioning properly. Lift pins 1 (not connected), 2 (A12), 23 (A11), 27 (write enable) and 28 (5V). You can also snip off pin 1 as it is not connected and is therefore useless.
 * 9) Carefully align the FRAM chip so that the back pins correspond with those of the original SRAM chip.
 * 10) Apply a generous amount of flux to the area and solder one of the back pins to anchor down the chip. Check your alignment to ensure that are no pins overlapping pads and that the pins sit in the center of the pads.
 * 11) Once you have verified that the chip is aligned, you may proceed with soldering it to the board. Place a small blob of solder on the tip of your iron and slowly drag the tip across the pins, watching out for the ones you have lifted. The flux will do most of the work for you and will help to spread the solder evenly across the pins. If you have solder bridging a couple of pins, apply more flux and "sweep" the excess solder away so that it collects on your tip.
 * 12) With the FRAM chip soldered down, inspect your work. You may also use a multimeter in continuity mode to ensure that the pins are properly connected.
 * 13) Using magnet wire, connect pin 28 of the FRAM chip to pin 26. Pin 26 is unused on the FRAM chip and is soldered to the 5V line of the original SRAM chip.
 * 14) Connect pin 27 of the FRAM chip to the pad sitting underneath pin 23. This is the write enable line which was previously connected to pin 21 of the original SRAM chip.
 * 15) Connect both pins 2 and 23 of the FRAM chip to either 5V or ground, as these are unused address lines.
 * 16) When rewiring is complete, inspect your work again and use your multimeter to check for possible shorts and that everything is properly connected.
 * 17) Reassemble the IFU and plug in a PC Engine with a system card inserted (any will do). When the CD-ROM2 System splash screen appears, press Select to enter the backup memory menu. Select the middle option to format the backup memory. If the FRAM install was performed correctly you should not encounter any errors.
 * 18) Test with a game which saves to backup memory, then use the CD system card to verify that the game was able to save a file. Press Select on the splash screen and select the top option to delete a save file. If there is a save file present, congratulations! No longer will you need to keep your system constantly powered on to retain your precious save files, and they will always be there no matter if it's been a day or 30 days since you last powered it on!