Re: HP48GX - HP49G+ = ? missing Message #10 Posted by James M. Prange on 11 Nov 2004, 11:47 a.m., in response to message #2 by Jonathan Purvis (NZ)
Quote: The 49G+ also has IrDA, so you might be able to use an IrDA
to RS-232 adapter.
Maybe, but note that most of the IrDA to RS-232 adapters on the
market expect to steal power from a PC's COM port and also require
that you install a device driver on the PC. Adapters without these
requirements are available, but are considerably more expensive.
I have an IrDA to COM port adapter, and for some things, it works
fairly well.
However, if I plug it into my USB host to RS-232 adapter instead
of to the PC's built-in COM port, it doesn't seem to get enough
power; the visible red LED still flashes when signals should be
being exchanged, but not as brightly. I guess that the IrDA may be
working, but not well enough to work with the 49g+'s intentionally
crippled IrDA. Maybe it would work with an IrDA compliant device.
The 49g+'s IrDA is supposed to be limited to 10 cm (4 inches) to
satisfy the "educational community", and that does indeed seem to
be about the maximum range to my IrDA/Rs-232 converter.
Like the 49G and 48gII "via wire" connections, the 49g+'s IrDA has
a flow control problem. SRECV can't reliably handle more than 255
bytes in a "chunk" without overrunning the receive buffer. With my
PC under extremely heavy load, some bytes are lost from an XMIT
command. Note that Kermit and Xmodem aren't affected by this.
You have to make sure that an IrDA connection has already been
established before using XMIT or a printing command, otherwise
bytes from the beginning of the transmission until the connection
is established are lost.
The 49g+ (but not the 48gII) can take MMC or SD cards. Anything
that the calculator stores on the card is formatted as a
binary-transferred file. Also note that the 49g+ uses only the
DOS-style "8.3" "short" filenames for the card. If you want to do
Kermit ASCII compatible transfers via the card, see my "49G+ ASCII
on SD" programs at http://www.hpcalc.org/details.php?id=6017
for a work-around.
The comp.sys.hp48 usenet group has much more information about the
48 and 49 series.
Regards, James
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