Crazy idea: CE 4.2 on a Jornada 728?

If someone were to spend sometime researching how the jornada works, and it's chips and whatnot, I'm sure they could hack it and use bigger ram chips and what not, I mean look at game consolesthey have modchips, larger harddrive replacements, the works, now if someone from let's say Team Xecuter got their hands on a Jornada, and totally modded it, I'm sure it would compete with modern PDA's. (Hoping for a 1 gb RAM chip)

Big-O

Edited by Big-O 2006-12-19 1:13 AM

don't know about 1GB of RAM in the Jornada. Modding an XBOX for a large hard disk is easy because the data cable remains the same and the complexity of the increased size is hidden behind the hard disk controller. In RAM chips, the data and address lines change width according to the size of the chip. So, in the case of the jornada, we _have_ to ensure that we use replacement chips that maintain the 12-bit/25-bit addressing scheme as well as the 16-bit data lines. In addition, we've got to ensure that the replacement chips still use the same control lines (chip select, /WE, /OE) that the Jornada uses. Is it possible? Assuming we can find appropriate chips, yes. Is it difficult to do that level of mod? Yes.

Right now, I think our focus should be on duplicating the existing flashboard design before we run off and try to mod it to death.

How much RAM does the existing flash board have? I don't really care about 1GB - I mean how would I ever use that much?. 64Mb would be a minimum though, preferably 128.

64MB is _probably_ doable (if ICs small enough are still being produced). 128MB might be a bit more chancy given that to support 128MB, the address lines will likely have to be wider. I'll look into it and see what I can find.

edit--
the existing flash board duplicates the original with 32MB of effective RAM (16MB per IC).

Edited by svet-am 2006-12-19 9:36 AM

The 720 has 32 Megs and the 728 has 64. It’s shared between acting as storage and system RAM both, of course. I think we mostly agree that 64 is a minimum. I'm just slightly concerned that for the Jornada it may be a maximum. Hope I'm wrong.

Edited by oflash 2006-12-19 9:54 AM

You are correct that the J728 is essentially the same except that it has 64MB of RAM.

edit-- strike my comments. it was early morning and I thought folks were still talking about the flash board.

Edited by svet-am 2006-12-19 9:47 AM

Hmm. I don't think I'd want a flashboard if it only had 32Mb and I assume that the majority on here would feel the same. Have you been in contact with the other guy that's involved with the boards?

I have been in contact with him. I'm ATM in the process of buying one of the pre-fabbed 64MB boards with the upgraded OS. I'll use it as a research platform for progressing forward.

Since I'll have a little bit of down time on my post-christmas trip, I'll see what I can find out about increased capacity memory and flash ICs. Personally, I'd be happy with 128MB of SDRAM on the board. SRAM would be even better, though it's a bit more costly. Depending on how much flash goes for, we may actually be able to get a very small Linux distro like DSL to fit entirely in the Flash.

Since I have Geoff Lyon's complete Protel project file set, I could _theoretically_ change the design to fit any memory IC so long as it maintains the addressing and pin-count rules. The hardest part for me (since I've not a lot of experience in this particular area) would be doing the various cutouts and perimeter shaping since the flashboard has to maintain a very specific shape.

I'll keep you guys abreast of my progress.

yes i have the binary dump (the files dump is actually extracted from that), i've uploaded it here: http://csakugy2.atw.hu/ROMj728.zip this is of a j728 but if you need 720, i can do a dump of that too.

thanks for your explanation, it was very interesting. i'll need to think a little more about the 12 bit data line and address stuff to understand it fully



thanks in advance! it would be really great.
oh btw i think i'd be happy with 64MB but of course 128MB would be better.

I've been taking a look at replacement SDRAM modules. Looks like we're going to top out at 64MB total. Here's the rationale:

64MB modules (we need two to make 128MB) come in the following basic flavor:

512Mbits storage x 16bits data bus.

When you get up to that large of a memory IC, however, you begin to require a total of 13 address lines (A0..A12) in order to access all of it. However, the design of the J720 memory board only allows 12 address lines (A0..A11). So, unless I can find some other memory ICs that take this into account, it looks like we're going to be limited based on the pinout and design of the Jornada.

Edited by svet-am 2006-12-19 2:36 PM

I take it by the "other guy" you mean Mark Gollahon? If you have, great - it looks like you two should be sharing thoughts. It seems that Mark's incredibly busy and that this never quite bubbles to the top of his todo list, so perhaps working together would provide the inspiration needed?

I think Mark did have a plan for putting more memory on there - perhaps, given the state of the address lines, bank switching was invovled? I really don't know, but have a look at the archives for the jornada linux mailing list if you haven't already :-D

Best of luck.

if you take a look at the pinout of the flash board, bank switching is already occurring on the memory ICs (they have a total of 4 banks such that the memory appears as 2Mx16x4 for the 16MB ICs). However, we cannot use more than two memory ICs because only one chip-select line is fed in through the connector from the Jornada mainboard (the other two chip-select lines are hardwired to GND) and the memory ICs that HP chose use address line 0 (A0) for a special 8-bit or 16-bit selection purpose. Not all memory ICs support this function (especially toggling it on this particular pin), so we have to make sure that we maintain that as well.

I'm buying one of the 64MB upgrade boards, so when I receive it I'll take a look at the 32MB modules to see what family they're in and see how the pinout looks so that I can determine if larger ICs can be used from the same family.

Could this little project make usb host on the jornada possible?

probably not if it's not supported already. i don't know where the USB controller is in the Jornada (it's likely in the system controller IC, but I do not know which controller IC was used in the Jornada), but most embedded system controllers either allow it or they don't -- there's no way to software modify that.

Edited by svet-am 2006-12-20 9:30 PM

That's a big No.