Re: HEPAX Pictures Message #7 Posted by Eric Smith on 10 May 2008, 2:40 a.m., in response to message #1 by PeterP
Thanks for posting the pictures.
The Fujitsu MB671209U is an ASIC, which acts as the controller for the memory parts.
Microchip 27C256-25/L is a 32K*8 OTP EPROM with 250 ns access time. That's where the HEPAX ROM code lives.
The other chip must be the SRAM, and it is most likely a common 32K*8 CMOS part, which was made by quite a few different vendors. A typical example would be a Hitachi HM62256, though I don't necessarily think that's the actual part in your HEPAX. The "-12LL" suffix indicates 120 ns access time and extra-low standby current.
The EPROM and SRAM could easily be replaced if they failed, though one would have to have the code to program into the EPROM, and know how it is organized. If the ASIC failed, the HEPAX would be toast, as the only source for a replacement would be another HEPAX.
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