HP 40gs ROM Update
Flash ROM - The HP 40gs contain flash ROM. A ROM chip contains "Read Only Memory" and is used to contain data which must be preserved even when the batteries are removed. For this reason a ROM chip is always used to contain the operating system for the calculator. Data that you create, on the other hand, is stored in RAM (Random Access Memory) and this memory lasts only as long as power is supplied to it. RAM data is lost when you remove the batteries or do a complete reset.
In normal ROM the contents of the chip are burned in at the factory and can’t be altered. The difference with the HP 40gs is that the ROM used is a flash ROM. This is a special chip where, although the contents are preserved when the batteries are removed or a reset is performed, the contents are not frozen permanently. Clearly this is far more useful than normal ROM but it is only recently that the price of flash ROM has come down to the point where it can be used in calculators.
The advantage of flash ROM is that it means that the operating system of the calculator can be updated if it turns out to contain bugs that HP didn’t spot before it was released, or if HP wants to add new features to the operating system. The 40gs still contain a small amount of traditional ROM that cannot be altered, but this contains little more than information the calculator needs on how to reboot itself and how to load a new operating system into the flash ROM when it becomes available.
Updated On: 15.07.08