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60 Hz modification tutorial for CDI660 and other Mono IV-based players. Also contains explanations on how to upgrade the NVRAM to 32 KB.
https://retrostuff.org/2019/10/14/philips-cdi660-mono-iv-nvram-and-60-hz-modification/
Posted : 14/10/2019 10:47 pm
Great article @rosewood!
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.
Right?
Posted : 15/10/2019 4:00 pm
Topic starter
Thanks, @omegalfa!
According to the service manual, this should work on any Mono IV board. I haven't verified this yet.
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.
Posted : 15/10/2019 8:21 pm
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.
Posted : 21/10/2019 12:50 am
Topic starter
Thanks for your input, @cdifan!
As soon as I've got a suitable player, I'll test it.
As soon as I've got a suitable player, I'll test it.
CDI490 is a 32 KB Mono IV player, I had one of them myself. Also, a CDI470 with 32 KB has been spotted in one of the CD-i Facebook groups. So, there must be a ROM with 32 KB and RTC support out there. (I've dumped a cdi490a.rom a couple of years ago, do you want to analyze it?)
I'm more worrying about the various CDI210 players, do you have information if the driver/device descriptor of those is ready for 32 KB?
Most system ROMs are already socketed, so it shouldn't be too complicated to replace them with an EPROM. On the other hand, those who went into the trouble of desoldering the TimeKeeper will also do it to the ROM...
Can you please check if this table at ICDIA is still correct: http://www.icdia.co.uk/players/comparison.html ?
It already lists the CDI490 as 32 KB player, but doesn't mention the a CDI470 with that RAM size.
And the CDI220/20 with Mono I board - I doubt that it supports 32 KB.
It already lists the CDI490 as 32 KB player, but doesn't mention the a CDI470 with that RAM size.
And the CDI220/20 with Mono I board - I doubt that it supports 32 KB.
Posted : 21/10/2019 9:08 am
Topic starter
It took me a while to find and configure a proper testing unit, but here are the results:
https://retrostuff.org/2019/12/29/philips-cdi470-32-kb-nvram-upgrade/
Posted : 29/12/2019 11:54 pm