I Have not tried the MagicRam, but have heard of 1 concern
using it. If a hard reboot(paper clip) is required. The
installed drivers are wipped out and need to be reinstalled
again before the card can be used.
>
> I'm wondering if this is a reliable alternative for
> (expensive) Sram cards (regarding: power consumption,
> compatibility, ...)
>
Some Manufacters Advertized Power numbers:
SRAM Power Consumption
MagicRAM SyncroTech Pretec
--------- ---------- ----------
Standard: 16mA 16ma
Peak: 150mA 150ma 120ma(max)
Standby: 1mA Max. 1ma 0.4ma(max)
Pretec ATA Flash Ram
--------------------
Power-saving read: 20 mA (Max.)
Power-saving write: 25 mA (Max.)
High-performance read: 65 mA (Max.)
High-performance write: 80 mA (Max.)
Sleep mode: 0.6 mA
Pretecs ATA Flash doesn't appear to be any worse than the SRAM cards (assuming
power saving mode). If anything the peaks are significantly less. Sleep mode
too.
ATA cards are not certified for use in the OmniGo 100. According to HP, only
SRAM cards should be used. But HP must have had some plans for ATA, since they
included ATA driver in the OGO ROM.
The difference I've been able to see between the cards is speed, cost and power.
The SRAM cards should be faster. (Insignificant on a slow PDA). They also
require a lithium battery backup to retain their memory. The cost per Megabyte is
also higher with SRAMS cards (1M ~ $110, 2M ~ 160). The ATA FLASH cards come in
higher densities and cost less per Meg(4M ~ $169, 8M ~ 256). The power draw by the
ATA flash cards seem to be about half that of the SRAM cards. 0.6ma vs 1.0ma for
standby and 30ma vs 100ma for read/write.
Again, not being an expert, nor an owner of a sram card, I'll explain to the best
of my knowlege. The sram batteries should not be affected significantly by usage.
(if they are supposed to last 1yr, they should last that long with heavy or mild
usage) The standby current on Sram (and ATA flash) cards is typically 1ma. This
amount of current draw should have very little impact on Ogo batteries. But (there
alway is a but) the current draw during read or write operations can be 40-120ma.
(this is significant) So what does all of this mean? If you are concerned with
battery life, keep the application data in the Ogo memory. Also keep very frequently
used applications in Ogo memory. This should help keep the battery drain down.
The application data is the most important, because it is accessed more frequently
than the application code.
I personally have an 4M ATA Flash card, and so far have noticed little impact
on the Ogo batteries, since I don't access the application on the card very much.
Man Wong Wrote(From archive):
The Pretec ATA flash works (and any fully compliant ATA flash should) w/out
additional drivers which is a plus in cases where the OmniGo's entire internal
memory gets wiped out which generally only happens from hacking/tweaking not
recommended by HP besides complete battery depletion. Again, HP does not
recommend use of flash cards even though the OmniGo comes w/ an ATA flash
driver preinstalled as drive E (vs drive C for SRAM cards), which is probably
why the Installer does not recognize it via the serial connection. However,
you can install stuff manually or via Installer onto the card using a laptop w/
pc-card slot which is a lot faster (if you have one).
Power draw >>from the OmniGo's batteries<< is **greater** for most any flash
card than typical SRAM. While SRAM does consume comparable amounts of power,
much of the power is drawn from its own battery not the PDA's while flash draws
all its power from the PDA. The Pretec ATA flash are marketed in two
factory-configured modes: power-saving at 20mA/25mA max read/write (roughly =<
SRAM draw) and high performance (default) at 65mA/80mA max read/write. I
believe it's actually faster than typical SRAM and much faster (~3x) than most
flash in high performance mode. Don't know about performance in power-saving
mode.
My Pretec ATA (at default mode) seems to shorten OmniGo battery life by 1/4 to
1/2 w/ only Pocket Quicken and a couple other frequently used apps/ebooks
running off the card. I would not recommend using the card as primary data
storage unless your data exceeds the ~300k realistic data limit on the internal
ramdisk because your apps will either run a lot slower or consume a lot more
power. Of course, YMMV. Anyway, despite the shortened battery life, I love
having a 12MB ATA flash (@ 11MB formatted) to increase the potentials of my
OmniGo (and its underlying GEOS/DOS base) manifold.
(End of Quote)
Sorry about the lengthy post. I assembled about 4 earlier messages on this
subject. When thing slow down this fall, I still plan on doing an Sram,
Linear Flash, and ATA Flash ram survey and FAQ.
Dom