I am a design engineer recently tasked with support of a product that was designed several years ago (late 1990s) by a company that our company merged with. The product uses a Motorola MC68HC11A1CFNE3 (Motorola became Freescale and now NXP) that was discontinued around 2010 and no longer available. Our company had been purchasing the original part from brokers but stock is drying up. The Freescale notice has a recommended replacement as MC68HC11E1CFNE3 (still available) but not fully equivalent. In comparing the two devices, it appears the only difference is the size of the RAM was doubled from 256 Bytes to 512 Bytes. Since our company's original engineers are long gone and the source of the source code is questionable at this time, what are the chances that I can drop in the available part and program it with the present image used with the original part and run successfully?