OT Troubleshooting: Old computers with modern parts

[Eric Smith]

I wrote:
> The FM18L08 is a 32K*8 3V 70ns part with unlimited endurance.  IIRC,
> the last time I bought some from Newark I paid under $10 each.

Ben wrote:
> But is that DIP packaging?

No, SOIC.  They used to make DIPs but they are phasing them out.
There may still be some in the distribution channel, but don't
count on future availability.

If all else fails you can solder the SOICs onto carrier boards that
will plug into DIP sockets.

> I got the data sheet but interfacing to 5v logic and power
> up is where I have lack of knowlage.  I still think  a generic  FRAM
> board needs to be made  with  3V parts to replace CORE memory in  older
> machines but  I have no idea how to interface 3V logic with 5 volt logic
> NOT using  CMOS parts.

What's wrong with CMOS parts for interfacing?

I wrote:
> If you want to use these in a 5V system, it's probably a good idea
> to use some 74LVC buffers that can function as level translators.

Ben wrote:
> SMT I think.

Available in DIP.  74LVC runs on 3V but has 5V tolerant inputs, so it
can be used to interface 3V CMOS to 5V TTL in both directions.
When powered by 3V, 74LVC outputs will not go above 3V, so they can't
drive pure 5V CMOS inputs.  However, many 5V VLSI CMOS parts will work
with TTL-level inputs (min 2.0V Vih), so 3V 74LVC can drive those
just fine.

In general, if you want to build things with state-of-the-art chips,
you're going to have to deal with SMT, whether you want to or not.

Eric