Chip to select output based on pulses

[Stonent]

I thought about a need for a chip in my time machine project that would switch a route based on pulses.  I don't know what I would call it so I don't know how I could google it.

I'm looking for a chip that's the equivalent to a SP8T switch.  So every time you send a pulse to the chip, it would advance to the next throw on the switch.

My idea was for addressing several 7 segment displays by sending a pulse each time I had finished pushing the output to it via a 74hc595 to change to the next cathode.  So the anode would be controlled by the 595 and the cathode would be controlled by this unknown chip. Is there a name for this kind of chip?

I know I could use a 3 to 8 decoder for switching to multiple 7 segment displays but I'd like to do it with 1 pin, preferably the unused 8th bit on the 595.

What do you think?  Right now I'm too far along to change my plans but I would like to know if there's a name for this type of chip for future reference.

[Simon]

Time machine did you say ? Pray do tell.

Sounds like you need a counter driving your demultiplexer (the 3 to 8 thing you mention). You pulse the counter, that counts up the addresses of you demultiplexer that will wuth each count change output in order, you just tie the demultiplexer input to VCC.

[arcom]

A 4017 decade counter will do what you want. I have used it in the past for 7-seg. displays but you need additional transistors to switch on the segments.

[rob77]

A 4017 decade counter will do what you want. I have used it in the past for 7-seg. displays but you need additional transistors to switch on the segments.

+1

4017 (decade) and 4022 (octal)

you can think of a 4022 as a 3bit counter + 3 to 8 decoder in one package , and 4017 is similar but counts to 10 and has 10 outputs.

[T3sl4co1l]

In the past, I just used an additional IO port.  But on that thing, IO ports weren't just pins on an MCU, I could chuck in another latch and decoder and put in as many ports as I wanted...
http://seventransistorlabs.com/tmoranwms/Elec_Z80.html

If you're running from an MCU, and don't have enough pins for the individual column selects, a decoder is good (three pins).  A counter-decoder and two pins (one clock, one reset -- make sure to reset it every cycle so it doesn't skip off into la-la land) saves you one more.  At that point, you'd be better off looking at the row drivers as well (e.g., a '595 driven by SPI -- now you're down to three and two pins, well within an 8 bit port).

Tim