Re: LZ: Extended mem. format


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Re: LZ: Extended mem. format



For future reference, all such posts are referring to "RAM Expander 
Beta", the plans for which can be found under "Plans & Guides" on 
ticalc.org...


<SNIP>
> No. Here are two practical solutions to extra memory for the calc...
> 
> 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.
> 
> 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.
> 
> Steve
> 
> p.s. To anyone that knows the ram+rom of the ti-85, is any of it unused,
> i wonder how hard it would be to tap the bus (wed only need maybe 16k of
> address space plus a free port or two for a page switcher. The problem
> would be fitting all the crap in the case. oh well.
> 




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