On 7/13/2016 11:30 AM, smf wrote: > On 13/07/2016 13:48, Gerrit Heitsch wrote: > >> In man circuits they control the EPROM through _OE and tie _CE to GND >> since that allows you to get away with slower EPROMs. This way the >> EPROM is always aktive and decoding addresses, just the output >> buffers are disabled. So you can hide quite a bit of the access time >> inside the delay for the decoder that selects the EPROM. Downside: >> higher power consumption with the old NMOS types. Doesn't really >> matter with CMOS. > > Exactly, which is why I suggested hooking up to _CE and using a > buffer. I am assuming that anything with a 2364 pinout is going to be > the same speed or slower than something with a 2764 pinout. I think you have it backwards. the OP wants to put a 2364 into a 2764 socket, so the 2364 could be much slower than the original socket expects. > > If the 2364 you are using is actually powered up all the time decoding > addresses and the _CE only turns on the output buffers _CE does not turn on output buffers. _CE is chip select. _OE turns on output buffers > then you could get away with just checking for (_CE | _OR ) == 0. You can do so, but that costs an OR gate, and most times, 2764 sockets just tied CE to ground all the time, as the power savings with CE =1 would not matter. In any case, the PCB in my store attaches _OE of the 2764 socket to _CS of the 2364. If your 2764 does the same, you're done. If it uses _CE to trigger (which I have not seen), cut the trace and jumper. If it uses both (which I have seen, though rarely), It's OR gate time. If you deadbug the IC, you can stash it in the interior of the 24 pin socket, as you only need 5 connections (A,B,Y,PWR,GND) Jim -- Jim Brain email@example.com www.jbrain.com Message was sent through the cbm-hackers mailing listReceived on 2016-07-13 18:00:02
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