Programmer is not responding Arduino UNO

Development Tools IDE 1.x
1

Hi, today I try to use my arduino for a project,but when I try to upload my code I got the message:

"avrdude: stk500_recv (): programmer is not responding" 2 times.
My operating system is Mac OS X 10.7.3
I use it on another computer with Windows 7 and it worked perfectly.
One thing that caught my attention is that in Windows the UNO model was listed under the board option, but Mac it doesn't appears. I installed the drivers that came in the folder I download.

When I upload my project and press shit the next text appears:

avrdude: Version 5.4-arduino, compiled on Oct 9 2007 at 11:20:31
Copyright (c) 2000-2005 Brian Dean, http://www.bdmicro.com/

System wide configuration file is "/Applications/Arduino.app/Contents/Resources/Java/hardware/tools/avr/etc/avrdude.conf"
User configuration file is "/Users/ernestofs1/.avrduderc"
User configuration file does not exist or is not a regular file, skipping

Using Port : /dev/tty.usbmodem641
Using Programmer : stk500v1
Overriding Baud Rate : 57600
avrdude: Send: 0 [30] [20]
avrdude: Send: 0 [30] [20]
avrdude: Send: 0 [30] [20]
avrdude: ser_recv(): programmer is not responding
avrdude: stk500_recv(): programmer is not responding
avrdude: Send: Q [51] [20]
avrdude: ser_recv(): programmer is not responding
avrdude: stk500_recv(): programmer is not responding

I also attach a picture of the board models that appear.

2

I suspect you are using an old installation on Mac which explains why the UNO board is not listed. Try re-installing Arduino 1.0.

You can't talk to the UNO as if it were a Duemillanove. The UNO bootloader uses a faster baud rate so it won't recognize any characters.