Universal Eprom Emulator

EE 54 September 1987 UNIVERSAL EPROM EMULATOR Any EPROM can be emulated by a RAM with double access: one for reading, and one for writing. The circuit presented here is situated between a host computer and the target system whose resident EPROM software requires fast and efficient editing, that is, without the use of an UV lamp and an EPROM programmer for testing the effect of any small alteration. An EPROM emulator can offer a significant time saving to pro- grammers engaged in writing, debugging, or upgrading resi- dent EPROM software. Virtually every computer operator knows that even a single wrong bit in an EPROM may require the de- vice to be taken from its socket, erased with ultra-violet light, verified for complete erase, and entirely re-programmed. Ob- viously, this is a time consuming procedure that readily ends up in one or more of the EPROM terminals breaking off. The EPROM emulator presented here enables modifying the EPROM contents while this is used in the target sy...