HP 39gs ROM Update

This is the place marker for the new HP 39gs ROM.

Flash ROM - The HP 39gs contain flash ROM. A ROM chip contains "ReadOnly Memory" and is used to contain data which must be preserved evenwhen the batteries are removed. For this reason a ROM chip is alwaysused to contain the operating system for the calculator. Data that youcreate, on the other hand, is stored in RAM (Random Access Memory) andthis memory lasts only as long as power is supplied to it. RAM data islost when you remove the batteries or do a complete reset.

Innormal ROM the contents of the chip are burned in at the factory andcan't be altered. The difference with the HP 39gs is that the ROM usedis a flash ROM. This is a special chip where, although the contents arepreserved when the batteries are removed or a reset is performed, thecontents are not frozen permanently. Clearly this is far more usefulthan normal ROM but it is only recently that the price of flash ROM hascome down to the point where it can be used in calculators.

Theadvantage of flash ROM is that it means that the operating system ofthe calculator can be updated if it turns out to contain bugs that HPdidn't spot before it was released, or if HP wants to add new featuresto the operating system. The 39gs still contain a small amount oftraditional ROM that cannot be altered, but this contains little morethan information the calculator needs on how to reboot itself and howto load a new operating system into the flash ROM when it becomesavailable.