Unfortunately, I haven't had time to look her for awhile. Eric, I haven't heard of NoTouch. What does it do? I'll have to go look. By compatible, we mean that the devices are software compatible and hardware compatible from an application system point of view. Its means that if you program the flash device with the same code you used in your 87C51 board, you can drop the flash part into the 87C51 board and it should run your application without problems. It is not intended to mean the have the same programming algo. BTW, the 87C51 does NOT have an erase command. It either had a quartz lid over the die and was erased by exposure to UV light, or, it was packaged in plastic and thus was an OTP (one-time programmable) device. Now about that fix......
if you have a board somewhere that can be used as an 80C31 then you can fix the SB/BV problem provided that the external execution security bit hasn't been programmed. Configure the board for external eprom mode (i.e- EA/ = 0). Then in the external eprom have some code that sets the ENBOOT bit (in AUXR1, I think). This makes the bootcode visable to your code. Then do a JMP to FC00h this will take you to the bootloader. Connect to a tool like FlashMagic and do a full chip erase. The full chip erase will erase and rewrite the SB & BV to their default values. - Bill