|Re: HP-49g+ and HP-50g|
Message #3 Posted by James M. Prange (Michigan) on 3 Nov 2006, 10:46 p.m.,
in response to message #2 by Ron Ross
Actually, what a 49g+ needs for doing a ROM update from an MMC or SD card is a card formatted FAT16.
When the 49G+ formats a card, it uses the card capacity to determine which file system to format it with. With recent ROM revisions, 8MB cards are formatted FAT12, 16MB and 32MB cards are formatted FAT16, and 64MB and larger cards are formatted FAT32.
But you can use something other than the 49g+ to format any capacity card to FAT16, and then use the card to update the ROM on the 49g+.
On a 49g+, recent ROM revisions can use a FAT12, FAT16, or FAT32 formatted card for everything except a ROM update.
I don't have a 50g, so I can't be certain, but I expect that it formats a card the same as a 49g+ does. I also expect that it can use a FAT12, FAT16, or FAT32 card for everything except, perhaps, a ROM update.
I've read that a ROM update can be done to a 50g from a card formatted FAT32 (as well as from a card formatted FAT16), which (assuming that's correct) is an improvement. I haven't read anything concerning whether a ROM update can be done to a 50g from a card formatted FAT12; I rather doubt it.
Going back to Antonio's questions, assuming a 49g+ and a 50g with the same ROM revision, I wouldn't expect any difference at all in the execution speed of programs, and the only difference in the functionality of programs would be that you can (assuming compatible hardware) use the serial port on a 50g. System flag -78 is used for switching between using the serial port and the USB port. Note that the serial port is not RS-232.
For that matter, the emulator for these calculators emulates the hardware Saturn processor (as used in the 48 series and 49G), not the "Saturn+" processor emulated on the ARM processor of the 49g+ and 50g, so the ROM used in the emulator has been tweaked back to using only the "legacy" hardware Saturn instructions. As a result, by removing the patches from the emulator's KML file, the current 49g+/50g ROM for the emulator can be used on the 49G. As far as I've noticed, the only glitch is that the VERSION command returns "Version HP48-C Revision #2.09" instead of "Version HP49-C Revision #2.09". As long as a program doesn't use HPGCC code or any of the new "Saturn+" instructions, it should run the same on a 49G as it does on a 49g+, although slower of course. In particular, any code should run the same as on the emulator, which means that any UserRPL or SysRPL code, or assembly language code that uses only legacy hardware Saturn instructions, should run the same. For details on upgrading the 49G to ROM revision 2.09, see this thread.
Another difference is that the 50g uses four AAA cells instead of three. Initially, it would seem that the battery should last longer, but it's been reported the "low-battery" voltage threshold is higher in the 50g, which would offset that effect. On the other hand, if you use NiMH cells in the calculator (I highly recommend this with the 49g+ and 50g), the 50g may give you a "low-battery" warning before the voltage is dropping so fast, thus giving you more time to replace the battery.
Another difference is that the 50g can be powered with 5V through the USB port. I don't know how much current it needs; it might not work with a "bus-powered" USB hub that can't supply the full 500mA that a USB port is required to be able to supply. There have been reports of the 50g not correctly switching back to using the internal battery and shutting down instead when the USB voltage is decreased gradually, such as when shutting down or restarting the PC.
Yet another difference is that the 50g's serial port provides, as well as ground, transmit, and receive lines, a connection said to be directly to the battery's plus terminal, reportedly intended as an option to supply power to whatever you care to connect to the serial port.
Well, given a connection directly to the battery, if you use rechargeable cells, it seems that you could recharge them while they're still in the calculator. Of course the charger would have to be appropriate for whatever battery you happen to use.
Edited: 3 Nov 2006, 10:47 p.m.