Would it be possible to upgrade the internal storage capacity of your CD-i player? Recently, we opted the possibility to upgrade a 8kb NV-RAM chip in a CD-i player with a 32kb chip. The idea was nicely picked up and investigated by Retrostuff.org. "If I want to upgrade a CD-i player NVRAM from 8Kb to 36Kb, I will need to remove the original timekeeper and add instead a Mitsubishi M5M5256DP-70LL-I 32Kbx8 SRAM chip in a battery-backed Dallas/Maxim DS1216C SmartWatch RAM socket , and add two resistors of 10kΩ each to place on 3270 and 3244 jumpers, and remove the 3241 jumper. "(Check for the numbers the service manual, avalable at ICDIA.co.uk) According to the service manual, this should work on any Mono IV board. But that's only theory, we didn't test t in practice. "About the jumpers: 3241 is a 4,7 kΩ resistor that can be removed. 3270 and 3244, however, are 0 Ω resistors - that means, just a wire or solder blob on the pads will be fine. In any case I'd suggest to use an extra 28-pin IC socket, so you can plug in whatever NVRAM solution and remove it again." according to CD-i member Rosewood.
CDifan thinks this whole idea is not possible: "I do not think the 32KB NVRAM upgrade will work, it might even result in an non-functional player. As I read the schematics, the jumpers take care of the different pinouts of the 8KB vs. 32KB RAM chip. This means that a modified player will technically have 32KB of NVRAM, but it will *not* have the real-time clock registers at the address expected by the ROMs (actually the player will not have a real-time clock at all), and without software modifications the ROMs might not even recognize the extra NVRAM.
So this modification probably requires a different NVRAM driver and certainly a different device descriptor, with the latter having a correctly set PD_RSIZ field, see FFGB VII.3.3.2.2, page VII-257 (this is a reference to the CD-I Full Functional Specification or Green Book reference, it can be found on ICDIA). I checked and the 220 ROMs have this field set to 32KB ($8000 hex) as expected, but the 470/490 ROMs have 8B minus 8 ($1FFF8), reserving space for the real-time clock registers (these are the only 8KB Mono-IV players). Depending on the coding of the driver, modifying the descriptor in ROM might work, assuming that you (and the ROMs) accept a missing real-time clock. This could be checked in software with CD-i Emulator, but I have not done so. On a real player it would mean physically desoldering and replacing the ROM chips."
In the meantime, Retrostuff has experimented with this in this article
[Thanks, Rosewood, CDifan, check out the Retrostuff article about the upgrade here]