[sdiy] TTL Etiquette?

[James Patchell]

Unused LS TTL inputs should, in general, be tied to VCC...I was always 
squeamish about doing that and would do so through a 1K resistor (regular 
TTL this was required)....

At 02:50 PM 9/20/2004 -0700, Metrophage wrote:
>I know, I am working on entirely too many projects at once, racing the
>decreasing temperature of the garage.
>
>This spring I bought my first laptop, a PowerBook 1400. Kind of like a
>jeep, it is very rugged and easy to modify or repair. Parts are
>plentiful and cheep. My intention was to use this as a portable MIDI
>sequencer. It works well with my multi-port Studio4 interface, but not
>the little "Professional Plus" I thought I'd use with it. Talking with
>some people formerly of Opcode Systems, and a little reading on RS-422
>data communications revealed why this portable interface only works
>with very strong serial ports... there are no balanced line drivers or
>recievers for the clock and signals!
>
>So this is my entry point to TTL stuff. I used a typical idea for
>deriving a 1 MHZ signal from an available 4 MHZ crystal. I got some LS
>TTL chips for i/o and buffers
 my layout looks compact.... but I am
>worried about the unused pins on the buffers and line reciever. I know
>this is probably very basic stuff, but I am worried that I should
>perhaps tie them to ground, or +5v, or just to each other. Maybe some
>unused pins I should orient a certain way, but others I may not need
>to? I figured I'd ask about the experiences of people here while I am
>deciding upon the wiring and component placement before I solder
>anything.
>Any ideas? Thanks!
>
>CJ
>
>
>
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         -Jim
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