[iPAQ] h3850 SDRAM Upgrade Question

to the Handhelds.org Gods, hail!

i know you are busy, so i'll try to keep it short and succinct.

as the proud owner of a ipaq h3850 running familiar v7.2 (hh37 kernel ) with
opie 1.0.3, i've seen stacked RAM upgrades as offered at www.ppctechs.com,
but it's a bit beyond my budget.
the site stated that it's possible to have a max of 256MB RAM on the ipaq!
so this got me thinking of doing it myself. (have tools and patience to try)

the http://handhelds.org/download/bootldr/CHANGELOG states: "2.17.21: Jamey
Hicks 1/10/02 -- added code to configure sdram bank1 (for 256MB ipaqs) (off
by default)"

***Question 1a*** how would i go about enabling this feature ?
***Question 1b*** will it be on code level and recompiling the bootloader?

http://ksteele.com/ipaq/memory-upgrade.html also has info on ipaq memory
rework.
http://web.archive.org/web/20030215122826/http://axl.freeyellow.com/iPAQ/rework.htm
shows an ipaq memory rework: removal of old chips, solder new chips and
stacking.
then connecting the stacked chips to a tesp point 67 that i assume is the
bank select pin/test point.

I suspect that the ipaq h3850's board differs greatly from the 3600. i tried
to find the test point pinouts for the ipaq h3850 on google, without succes.
then i read the Intel® StrongARM* SA-1110 Microprocessor Developer's Manual
http://developer.intel.com/design/strong/manuals/278240.htm (whoa, pretty
heady stuff)
in an attempt to find out which pin would be used to select the 2/3rd bank.
it turns out there are four i think, feel free to correct me. (pin 131, 132
133 and 134 for nRAS/nSDCS 0 to 3.)
bloody difficult to trace them on the board without destroying my ipaq.
another option i've thought about is to order an h3850 board and use the
technique described here http://www.xda-developers.com/jtag/ to find out
what pin goes where.

***Question 2a***does anybody know which tesp point(s) on the h3850 are to
be used to select the other memory bank (stacked chips)
***Question 2b*** and for that matter, what are different test points
pinouts?
***Question 2c*** is this info secret as in NDA?

the h3850 has two 48LC32M8A2 32MB SDRAM chips. the developers manuals states
"The SA-1110 supports most x4, x8, x16, and x32 SDRAM"
this link http://www.handhelds.org/Compaq/iPAQH3600/iPAQ_H3600.html has some
info on chip sizes and configurations for the 3600 but any sort of hardware
design specs on the h3800 series are impossible to find.
this site has a detailed description of SDRAM chips:
www.imagiq.com/RAMGuide.html which leads to the question:

***Question 3a*** assuming once again that some of this info is relevant to
the h3850( same processor) what size and configuration of SDRAM chips can be
used to get a total of 256MB (megabytes)?
***Question 3b*** is it possible to use two 128MB chips (and sidestep the
whole chip select test point)?
***Question 3c*** if so, then what configuration of 128MB chips are to be
used? eg http://www.micron.com/products/dram/sdram/ 128MB chip (as 32 Meg x
4, 16 Meg x 8, 8 Meg x 16, 4 Meg x 32)?
***Question 3d*** is the 256MB a SA1110 hardware limit? (memory map 512MB
starting at 0hC000 0000) or a memory chip density limit? or bootloader
limit?

Thank you for the continued hard work! handhelds.org = Über.

cds
Received on Sat Oct 30 2004 - 23:55:05 EDT