CacheCard FAQ & Answers from Jafa

1. Can the cachecard be used just as a network card and then later on add the memory to use the caching part? Or must the memory be present for it to function at all?

The ethernet and cachecard drivers are separate and it will work as ethernet only or as caching only. The default installer will install both drivers so you will get a caching warning at startup... just ignore the warning.

2. Is this hardware beta, or is this the final version?

It is the first-run - post-beta, the first run made in any quantity. The hardware is the final version... the only possible changes in the future will be to make the manufacturing or testing process more efficient. I will endeavor to make any software patches available in a timely manner if there are any problems. Based on past experience the most likely software problems will be the installer complaining that it couldn't find/detect something that was moved by another mod.

3. Have we confirmed that the database is limited to 512MB even for very large disk configurations (e.g. 320+320)?

On a SA the database is always 512MB regardless of the disk sizes, on a DTivo there are two 512MB database partitions. The cachecard supports 1GB of cachable harddrive area and will map that into whatever memory you have installed. I am recommending 512MB because that will cache the entire database on a SA and the primary database on a DTivo. If the secondary database is accessed then it will be cached on demand as well.

4. How will network performance be with this card - will it be any faster than a TurboNet card or should it be the same?

The Ethernet interface itself has about a 3x increase in bus bandwidth to the TiVo.  Obviously the actual speed increase will be limited by the TiVo... I will take some measurements next week when I get a chance.

5. With the database cached in memory, does the Now Playing list now appear almost instantly? With my current setup, it often takes 12 seconds for my program list to appear.

The cachecard speeds things up 2-3 times so it may still take a few seconds if you have that many shows and it normally takes 12 seconds to display.

6. Will this speed up things that we are not allowed to discuss on the AVS?

It depends what you want to speed up... (jafa avoids eluding to any form of sexual act as we are not allowed to discuss that here). Reducing CPU overhead was the design goal... that includes the network interface. As a result of reducing the network overhead the interface goes faster. For the daily call the speed is regulated by your internet connection - the advantage is that less CPU time is used during the process.  For legit uses that need higher speed (for example, using your tivo as a ftp backup server) the reduced overhead means higher throughput. Please note that the terms-of-use on my site... they apply to the CacheCARD as well - http://www.silicondust.com/terms_of_use.html

Yes. BTW www.dealdatabase.com/forum

7. If I just do a direct replacement with this card in a DTiVo that already has Turbonet card running will it function WITHOUT additional driver install (assuming the cache portion is NOT used) ??

Sorry, the chipset and driver is completely different. You will need to burn the installation CD and install the custom software as with earlier TurboNET installs.

8. I'm thinking of getting the cache card. Do I need to load a software driver or just install the card and put in memory?

Yes, it does need a driver to be installed.... there is an installation CD - if you have upgraded the drives in your tivo then you can install the drivers no problem.

9. If I already have a TurboNET installed, can I copy the driver over with FTP with the old TurboNET card, then swap it out and put in the new one, or do I have to remove the drive and put it into a PC for the installation?

My primary focus is making sure that the CD is easy to use and works for everyone. I can't guarantee I will have a native installer in place in the next three weeks but I can see the benefit and will see what I can do.

10. Any chance of seeing a cache card/airnet combo?

I thought about it but I can't make it physically fit in a DTivo (it is a tight enough fit as it is) and most people have been asking for Ethernet. I would recommend considering a Linksys WET54G - You will get the higher G speeds and it can bridge multiple devices if you add something else to your entertainment system that is Ethernet enabled.

11.  Is there just a plain cache card available?

No, but you do not have to use the network interface. But it will be there for future use.

12. So given I have a DTivo, would it be worth my money to go ahead and buy 1GB for this? Or do you think 512MB is enough for most situations?

I am not sure I would bother... 512MB is worth it... 1GB is more questionable. The tag RAM covers both DTivo database partitions so both are cached with 512MB.

13. The main reason I would consider buying one of these is to improve the speed of the guide and channel changing. Will a cachecard significantly improve those things?

The speed of the channel changing can't be improved - it is determined by how long it takes for the tuner to lock to the signal. If you have a separate set-top box then it the speed you set for the IR blaster also makes a difference. Yes, the speed of the guide is improved. The longer the operation takes normally the more noticeable the speedup - rearranging the season passes is a good example.

14. What is the possibility of a "series 2" compatible CacheCard in the future?

It all comes down to mechanics... there is a technical solution but it won't physically fit.

15. Can the card be used with less than 512KB RAM? I have 128KB SDRAM from a older Dell I am salvaging.

It will work with 128MB of RAM (one of my tests is with 32MB of RAM)... the disadvantage is that it will take longer for the cache to train on the database so the out-of-box experience won't be quite as good. I have not measured the actual performance difference - I just figured that 512MB DIMMs were cheap enough.

16. Will any PC133 SDRAM work? I assume it can be unregistered RAM too? For example: Micron Technology (System Memory) -512MB PC133 PC100 168Pin Sdram Unbuffered 64x64, NonECC,CL2.5,6layer board

It takes standard PC100/PC133 SDRAM - that means 3.3V, unbuffered SDRAM. All 512MB configuration options listed in the copy of the JEDEC standard I have are supported.

17. If the database is moved to RAM, what happens if the power is lost or you reboot the TiVo? Does the database have to be rebuilt?

If the power goes out then you won't be watching TV! The cache is write-through - ie it only caches reads. All writes always go to disk in the same order as normal. If the power goes out then it the disk will contain exactly the same contents as it would otherwise have had at that exact same point in time if there was no caching going on.

18. So what happened to the older reference design you had started with?

The v1 cachecard plugged into the IDE cable - the design does work.  I proved that much of the benefit comes from allowing the tivo to make forward progress while the harddrives are seeking to read/write video data (full-length write seek is usually about 26ms on your "9ms" drive).  The way that IDE works on a Tivo is the bus is tied up for the duration of the seek plus read/write so if you get a cache miss (ie video) then the tivo can't make forward progress for up to 26ms. The v1 cachecard cycle-steals to make forward progress but there are two problems: (1) I couldn't figure out how to make it mechanically fit in a DTivo. I could make it fit if it plugged directly into the back of the master driver but then you couldn't have two drives installed. (2) Cycle-stealing meant that I couldn't use DMA. It turned out that a TiVo doesn't go anywhere as fast as the IDE standard allows for non-DMA transactions, every transactions is buffered through the ASIC on the board, and the IDE bus is only 16-bit wide. It still doubled the the speed of the Season Passes but I wasn't happy with the low-level transfer speeds. The v2 plugs directly into the motherboard connector. It uses the full 32-bit bus and is synchronous with the core clock for the highest bandwidth to the PPC.

20. I'm concerned about the fit. It's already tight enough in there with the tiny TurboNet card and two drives - sometimes I think the second drive's cables will push the card off the connector. It seems that the Cachecard is taller? Where does the DIMM go?

Yeah, its a bit of a snug fit. On a DTivo the DIMM sticks out over top of the two harddrives.

21. Can the Cachecard use cheapo CAS3 memory? I can find 512MB of that for $42, but if I need CAS2, it costs more...

CAS timing - The rated frequency (eg 133MHz) is the maximum frequency that the memory can burst data/be clocked at. Before data can be burst the column must be selected and that takes time (regardless of frequency) for the RAM to do. When they say CAS 3 timing that means that it takes 3 cycles @ 133MHz... it should handle CAS 2 timing at lower frequencies. The cachecard supports both CAS 2 and CAS 3 timing but by default it always puts the RAM in CAS 2 mode because I have yet to find a RAM that didn't support it at the TiVo clock frequency.

22. Is it even possible to overclock the cachecard? I got the impression that it was locked to the processor clock...

Yeah, you can't run the memory at a higher speed than the processor.

24. Is ECC memory is supported or not. Jafa, can you give a definitive answer?

ECC memory will work fine but the extra ECC bits are not used (ECC memory does not actually do ECC... it is just slightly wider so if the motherboard supports ECC then they can be used for that purpose). The driver maintains a checksum of every sector so if there are any data errors it will be detected, logged, and re-loaded from the hard drive. In other words, if it wasn't clear, ECC is just ignored, but tolerated.

25. Do memory modules using 64MBx4 chips work?

512MB DIMMs based of 64MBx4 chips work fine.

26. Hey Jafa, could you integrate the 48 bit kernel upgrades into your cache patch? Then I could take care of two things at once. Dunno if it's possible, just throwing the question out there.

The cachecard driver is a stand-alone installable module - you do not replace the kernel. It will work with both a stock and a LBA48 kernel.