Document ID: TOS-WIKI-REF-007 Revision: 1.0 Author: ThisOldScot
Section_1: Overview#
Vintage game cartridges (NES, SNES, Mega Drive, Game Boy) utilise volatile Static Random Access Memory (SRAM) to store save data. This memory requires a constant electrical current from a 3V lithium battery to prevent data “evaporation.” Once the battery dies, the data is lost, and the physical battery becomes a chemical liability.
In the Borders Workshop, we utilise Ferroelectric RAM (FRAM) migration. FRAM is a non-volatile memory technology that retains data without a battery while maintaining the high-speed write cycles required by original console hardware. This is the definitive “Heritage Solution” for permanent save data preservation.
Section_2: Tools & Materials Required#
| Item | Spec | Purpose |
|---|---|---|
| FRAM IC | FM18L08 / FM16W08 | Replacement non-volatile memory chip. |
| Soldering Iron Hakko FX888-DX | Mini-Chisel Tip | Precision SMD removal and installation. |
| Solder Wick | 1.5mm (Fine) | Clearing original SRAM pads. |
| Logic Gate | 74HCT00 (NAND) | (Optional) Managing specific SNES /MD chip selects. |
| Kynar Wire | 30AWG | Logic jumpers for address/control line redirection. |
| IPA (99.9%) | Anhydrous | Post-surgical board cleaning. |
Section_3: The Restoration Protocol#
STAGE_3: 01 // Diagnostic Verification#
- Verify the original SRAM chip ID (e.g., LH5168 or HM6264).
- Forensic Step: Check the save battery voltage. If $<2.8V$, the data is already at risk. Use a Cartridge Reader (e.g., Joey Jr or Retrode) to backup the existing save file before desoldering.
STAGE_3: 02 // SRAM Extraction#
- utilise the SOP-8/QFP Extraction Protocol (TOS-TOOL-REF-014).
- Apply tacky flux to the SRAM pins and use Hot Air at 330°C to lift the chip.
- Clean the pads with 99.9% IPA and solder wick until the surface is perfectly planar.
STAGE_3: 03 // Address & Logic Mapping#
SRAM and FRAM often share the same JEDEC pinout, but with one critical difference: The Write Enable (/WE) Logic.
- SRAM Logic: Data is “locked” when the battery voltage is higher than the VCC rail (Standby Mode).
- FRAM Logic: Data is permanent. However, some consoles pulse the
/CE(Chip Enable) line in a way that can trigger accidental “bit-flips” during power-down.
STAGE_3: 04 // The “No-Battery” Bypass#
- Remove the original battery and its mounting tabs.
- Scrub the area with White Vinegar if any verdigris is present.
- The Bridge: Most cartridges require a 10k Ohm pull-up resistor on the
/CEline to ensure the FRAM chip stays “Disabled” until the console is fully stabilised.
STAGE_3: 05 // FRAM Installation#
- Align the FRAM IC (Pin 1 orientation is mandatory).
- utilise the Drag Soldering Technique (TOS-TOOL-REF-016).
- Verification: Check for continuity between the FRAM VCC pin and the cartridge edge connector’s 5V pin. It must be a direct path, bypassing the original battery-management diode.
STAGE_3: 06 // Save-File Injection#
- Use the cartridge reader to restore the backed-up
.savfile to the new hardware. - Perform three “Power-Cycle Tests” (Wait 60 seconds between boots) to confirm the data persists without a battery.
Section_4: Technical Warning#
Safety_Warning
VOLTAGE COMPATIBILITY ALERT: Many modern FRAM chips (FM18L08) are 3.3V only. If installing into a 5V cartridge (NES/SNES), you must use the “W” or “L” series (e.g., FM16W08) which is 5V-tolerant, or integrate a Logic Level Shifter (TOS-LOG-REF-002). Feeding 5V into a 3.3V FRAM will result in immediate silicon termination.
Section_5: Practical Application: Restoring The Legend of Zelda#
A gold NES Zelda cartridge was received with zero save capacity. Following the FRAM Migration, the battery was permanently removed. The game now saves and loads instantly, and the client no longer faces the 10-year “Battery Anxiety” cycle. The cartridge is now an archival-grade artifact.
Section_6: Heritage Logic Note#
While removing the battery changes the internal aesthetic of the PCB, the Borders Workshop authorises this modification as a Preservation Necessity. The chemical risk of a leaking lithium cell outweighs the aesthetic value of the original battery tabs.
Files, Tools & Materials
Everything used in this build — documentation, downloads, verified hardware and the tools that made it possible.
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