Re: LZ: Extended mem. format
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> >Passive. We interface a microwire eeprom (its three wires, clock, data
> >in, and data out. I believe its possible to combine the data in and data
> >out using passive components, but well have to look into that). I Have a
> >500k-byte EEPROM with a microwire interface, if that isnt enough, they
> >have a 1-meg one you can buy. Basically we wire this to the link port,
> >and do the rest in software.
> >
>
> I've completed a circuit that will interface the Microwire Chip. It
> isn't very easy to multiplex the data in and data out lines, but I
> think I've done it using about 3 other 74LSxx parts. All my findings
> will be posted on my web page some time tonight or tomorrow (I'll send
> the address to the list). The big headache is that the chips only
> come in surface mount or PLCC packaging, which will make soldering a
> big PAIN!!!
>
> >Active. I like this one better, because you could add a lot more to it.
> >Basically, you take another microprocessor (Probably a Z80, since we
> >already know how to program it) We could hook it up so that if your calc
> >got reset, you could program the thingy to automatically send a backup
> >to the calc if you did an input "cblget",blah or whatever on a cbl calc
> >and go to link receive or whatever. This way there could be variable
> >send/raw send/etc. The only problem is that i doubt if anyone has had
> >any experience working with microprocessors and stuff (Me Included, i
> >got the idea from my Z80 book). Wed at least need a microprocessor, rom
> >code, actually, would probably be eeprom that would be locked by a
> >special switch so that updates could be done without needing a burner.
> >Wed also need either static ram or eeprom, or both maybe. We could leave
> >the scematics open-ended (same with the rom code) so that if someone
> >wanted to use eeprom for no-power storage, and static ram for fast
> >access, although it would be through the link port, so it would be
> >pretty slow. Anyway, i think the practically of this is limited by the
> >fact that it would be to big and bulky.
> >
>
> I have enough experience with microprocessors, but I can say right now
> that it's not worth it. For one thing, finding Z80 processors is
> difficult to do these days. I think NTE makes Z80 clones right now,
> but they probably charge an arm and a leg! Out of my 5-10 electronics
> supplier catalogs, I have yet to see the Z80 listed. That doesn't
> matter, however, because the Z80 wouldn't be the best choice. If you
> absolutely must use a dedicated microprocessor, use some of the single
> chip microcontroller's like the 68HC11, the Z8, the Basic Stamp, or
> even the 8051. The Z8 would be nice because it has the Z80 core. In
> any case (like I said in the expander doc's) using a microcontroller
> is just not worth the effort. Most of the uP's functions could be
> emulated with passive components.
>
> The best solution (as you'll see soon) is the National Semiconductor
> Serial Flash chips. All the info will be posted to my web page
> tonight.
>
Well, I'm going to try anyways because I think it will be fun. And,
out of my 3 catalogs, one (Jameco) has it and a 6mHx one costs $2.49.
-Ed
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