Re: 50G vs 49G+?
Message #4 Posted by James M. Prange (Michigan) on 9 Apr 2007, 5:10 p.m.,
in response to message #3 by Ron Ross
Quote:
Keyboard is significantly better than all but the latest last year
production of Hp49G+s.
Indeed, I rather suspect that the main reason for the model change
was to distinguish the newer units from the 49g+, which has a very
bad reputation for keyboard problems.
Quote:
The 50G also has an RS233 compatable serial port (well to most,
not so fussy RS232 devices). No cable is readily available
though.
No, the serial port of a 50g is not RS-232
compatible. To use it with an RS-232 device, you'd need at least a
level-shifter, and possibly an inverter. The signal at the port is
about 0V and +3.3V, but I don't know whether +3.3V represents a
logical 1 or a logical 0.
So far as the cable goes, the serial port uses a non-standard
("captive") "4-pin USB mini-B" connection. No doubt one could
build his own level-shifter.
Samson Cables is
supposed to be planning to market a suitable cable/adapter real
soon now.
The serial port also provides a connection to the battery
terminals. This is supposedly for an option to provide power to
whatever the user chooses to connect to the port, but, with a
non-rechargeable battery disconnected, could be used to power the
50g, or with a rechargeable battery installed, could be used to
recharge the battery as well.
Quote:
You use 4 batteries vs 3 for the older Hp 49G+. This should
result in longer life between battery changes.
Well, it will extend the battery life if the 50g draws less
current from the battery, but I don't know whether anyone has
actually measured this.
Quote:
USB is now powered from PC which can theoretically extend battery
life. However, the typical user doesn't keep his Hp tethered to a
PC.
Perhaps more important is that via USB transfers and flash ROM
upgrades won't be aborted due to a low battery condition.
The 50g can also be powered through the USB port with a 5V
adapter, such as the ones available for various music/video
players. The 50g requests 50mA from the USB, so any adapter that
can supply at least 50mA at 5V should be okay. I don't know how
much current the 50g actually draws; I expect somewhat less. I
expect that the highest current requirement would be when writing
to flash memory.
Note that the 49g+ and 50g seem to work well with NiMH cells,
except that you won't have as much time between a low battery
warning and the battery going too low to work at all. I suggest
keeping a spare set of AAA cells easily available if you use
rechargeable cells, but using them should save on battery costs.
For that matter, the 48 series and the 49G also seem to work okay
with NiMH cells, but the battery life is usually much longer with
those models, so I think that alkaline cells are usually more
appropriate for them.
The 50g uses the same (flash memory) "ROM" as the 49g+, so except
for using system flag -78 to select whether the "via wire" I/O
uses USB or the serial port, programming should be the same.
Regards,
James
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