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audiotek

macrumors newbie
Original poster
Mar 27, 2015
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0
I have 2 iMacs

Mid 2009 and a 2011

Without getting a KVM how can I only use 1 mouse and 1 keyboard to access both iMacs? They are both sitting on my desk side by side.

A friend of mine mentioned to connect both iMacs with a Thunderbolt cabler and use F2 to switch between the 2 I tried it but I don't think the 2009 supports that option.

What else could I use?
 

EugW

macrumors G3
Jun 18, 2017
9,606
7,022
I might try Synergy Besides that there's no other easy way? USBC to Display Port works?
Yes, I am using a Monoprice USB-C to DisplayPort dongle for my 2017 iMac, paired with a DisplayPort to Mini-DisplayPort cable from the dongle to the 2010 iMac.

I think for your setup, if you wanted to use your 2009 iMac as a second monitor, all you would need is a Mini-DisplayPort cable. (You wouldn't be connecting via Thunderbolt. You would be connecting via Mini-DisplayPort.)
 
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EugW

macrumors G3
Jun 18, 2017
9,606
7,022
OK so that will act as a KVM?
No. My method turns the 2nd iMac into a dumb monitor (ie. extended desktop from 1st iMac).

If you want to use the two iMacs as two separate computers but with a common mouse and keyboard, then you need to run something like Synergy.
 
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MacUser2525

Suspended
Mar 17, 2007
2,097
372
Canada
I have 2 iMacs

Mid 2009 and a 2011

Without getting a KVM how can I only use 1 mouse and 1 keyboard to access both iMacs? They are both sitting on my desk side by side.

A friend of mine mentioned to connect both iMacs with a Thunderbolt cabler and use F2 to switch between the 2 I tried it but I don't think the 2009 supports that option.

What else could I use?

Screen sharing would do what you want allowing you to control/use the second machine from the one connected to the mouse and keyboard, best done from the machine with the higher resolution screen.
 
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theluggage

macrumors 603
Jul 29, 2011
5,398
4,491
I might try Synergy Besides that there's no other easy way? USBC to Display Port works?

Neither of your iMacs has a USB-C port....!

If you want to run two macs side-by-side, each using their own display, and operate them from a single keyboard and mouse, Synergy is exactly the tool for the job: just move the mouse off the side of one computer's screen and it pops up on the other one, and the keyboard input automatically follows it. There's also limited cut & paste support.

It just needs a network connection between the two macs - WiFi will do fine. Its about $20, or you can waste more than $20 worth of your time trying to find an old, free version or you can spend $20 on a cable that might not actually do what you want...

The other possibility for doing what you want is something like this:

https://www.amazon.co.uk/Plugable-One-Button-Swapping-Between-Computers/dp/B006Z0Q2SI

Basically, a KVM switch without the "V" part. You might consider that over Synergy if...
(1) Synergy doesn't play nicely with some software you're using - most likely games - or the slightest hint of extra latency gets you shot.
(2) You frequently need to use different boot options on the "remote" Mac (e.g. for alternate startup drives) before Synergy would have a chance to start
(3) You don't, for some reason, want the remote machine to always start the Synergy client on boot.

I've actually used one of those together with Synergy for those reasons - but I was juggling 3-4 Macs/Linux/PCs and displays so I'd often need to re-configure Synergy or change boot options.

The other solutions suggested here...

"Screen sharing" would duplicate the screen of one Mac in a window on the screen of the other Mac. Yes, it lets you control one mac from the other, but its not what you want if the screens are side-by-side.

Connecting the second mac using "target display mode" - (https://support.apple.com/en-us/HT204592) makes one Mac act as a second display for the other - doesn't actually solve your display switching problem so you might still need Synergy and/or the USB switch.

If you want to do that, you need to use the 2009 iMac as the "target display" and connect the 2011 iMac to it using a miniDisplayPort-to-miniDisplayPort cable - not a Thunderbolt cable. The 2009 doesn't have Thunderbolt and can't do anything with a Thunderbolt cable. The 2011 can only act as "target display" for other Thunderbolt Macs, but it can output MiniDisplayPort.
 
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Anonymous Freak

macrumors 603
Dec 12, 2002
5,446
896
Cascadia
If you want to use your already-owned keyboard and mouse, Synergy or Teleport are the best options. Work best if they are connected via fast network connection (Ethernet to a Gigabit hub/router.)

If you are in the market for a new keyboard/mouse, I've been happy with the Logitech MX Anywhere 2S, which supports Logitech's "Flow" feature - if you have one of their "Flow" capable mice (the MX Anywhere 2S or a few other mice,) plus a supported Logitech keyboard (a few to choose from, in a few different styles,) it can be set up so that you can just "mouse to the edge of the screen" on one computer and the keyboard and mouse actually switch inputs to the other computer.

With Synergy or Teleport, the computer the keyboard/mouse are actually plugged in to (or are wirelessly connected to) has to be on to use them with the other computer - and it can't wake up the other computer. With Logitech's system, it actually switches the connection from one computer to the other, so you can shut off the first computer. And it will wake up the other computer, just as clicking a button on a Bluetooth mouse will wake up the computer it is connected to.

(No compensation from Logitech, just a fan of this tech they have - and I hope other manufacturers do similar with their "multi device" keyboards and mice.)
 
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blue_serotta

macrumors newbie
Apr 5, 2020
3
0
If you want to use your already-owned keyboard and mouse, Synergy or Teleport are the best options. Work best if they are connected via fast network connection (Ethernet to a Gigabit hub/router.)

If you are in the market for a new keyboard/mouse, I've been happy with the Logitech MX Anywhere 2S, which supports Logitech's "Flow" feature - if you have one of their "Flow" capable mice (the MX Anywhere 2S or a few other mice,) plus a supported Logitech keyboard (a few to choose from, in a few different styles,) it can be set up so that you can just "mouse to the edge of the screen" on one computer and the keyboard and mouse actually switch inputs to the other computer.

With Synergy or Teleport, the computer the keyboard/mouse are actually plugged in to (or are wirelessly connected to) has to be on to use them with the other computer - and it can't wake up the other computer. With Logitech's system, it actually switches the connection from one computer to the other, so you can shut off the first computer. And it will wake up the other computer, just as clicking a button on a Bluetooth mouse will wake up the computer it is connected to.

(No compensation from Logitech, just a fan of this tech they have - and I hope other manufacturers do similar with their "multi device" keyboards and mice.)
Can anyone confirm that this (e.g. Synergy or a KM switch) DOES NOT work? Again, to be clear, I also have two iMacs, both late 2013, and just use one currently. The second iMac does not have a keyboard or mouse. I want to run both iMacs side-by-side, utilizing my one keyboard, one mouse, and one trackpad. Again, to be clear, I need to be able to boot both iMacs, using one keybd, mouse, trackpad. Ideally, I can get a KM (A/B) switch to boot from iMac A, then iMac B. I'd then have both iMacs running but I think the first iMac would balk when I switched it to iMac B. I cannot see how Synergy would work.
 
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Anonymous Freak

macrumors 603
Dec 12, 2002
5,446
896
Cascadia
A keyboard+mouse switch will do what you want for USB keyboard and mouse. And nearly all of them continue to present that a keyboard and mouse is present to the 'other' device if it's a somewhat modern electronic switch that supports hotkey switching. Older "dumb" KVM devices that you have to physically rotate a dial or press physical switches on the device won't, but basically any one sold now will.

Synergy will work once both Macs are booted in to their OSes, but will not give you boot-time access to whichever is the "secondary" device; meaning you couldn't log on to it, even.

Note that KM switches only work for USB keyboards and mice - I've never heard of a Bluetooth KM switch. If you want wireless, or to use an Apple Magic Trackpad, you're out of luck, there is no way to do that easily.

My suggestion was that if you are in the market for *new* keyboard/mouse, look in to Logitech's "Flow-enabled" series which can switch between devices seamlessly like Synergy would, but by actually switching inputs, so are usable at boot-time. And operate over either RF-wireless USB receiver or Bluetooth. (I use it between two Macs and a Windows computer, one Mac and one Windows via Bluetooth, the other Mac via RF USB dongle.)

Also, with 2013 iMacs, you have another feature at your disposal - Connect a Thunderbolt cable between the two and use Target Display Mode to use your second iMac as a second display for the first one! (That's one of my systems.) The second iMac is still running, so can be used a server (which is what I do,) while acting as an extra monitor for your other Mac. (The only caveat is that it only works when both systems are running macOS - if either one is booted to Windows, it won't work. The feature also went away on the "Retina" iMacs, the 4K and 5K models, it only works on the pre-Retina, Thunderbolt-equipped models and the original 27" pre-Thunderbolt models. The pre-Thunderbolt 21.5" models don't work, only the ones with Thunderbolt.)
 
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mj_

macrumors 65816
May 18, 2017
1,462
1,069
Austin, TX
My suggestion was that if you are in the market for *new* keyboard/mouse, look in to Logitech's "Flow-enabled" series which can switch between devices seamlessly like Synergy would, but by actually switching inputs, so are usable at boot-time. And operate over either RF-wireless USB receiver or Bluetooth. (I use it between two Macs and a Windows computer, one Mac and one Windows via Bluetooth, the other Mac via RF USB dongle.)
While I absolutely second your suggestion in general I want to add that Logitech Bluetooth devices are not available on Macs with enabled FileVault at boot time as macOS lacks the proper pre-boot drivers. In other words: if you have FileVault enabled and want to use Logitech input devices you will need to use the provided Logitech Unifying Receiver instead of Bluetooth.
 
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blue_serotta

macrumors newbie
Apr 5, 2020
3
0
Hi Anonymous,
Pardon me for my old, tired thinking. My brain still sees multiple Medusa-like bramble-bushes of cabling between systems and sketchy KVM switches and it's hard to imagine I can cobble a clean, functioning dual iMac system! Can you recommend a specific "Flow-enabled" keyboard + mouse? Is there a trackpad that I can use? (not mandatory, though) I've attached a screenshot of the specifics of the type of iMac I have (the other is dormant but am very certain it is the same).

It's really difficult for me to wrap my head around that when I fire up each computer, each one will see the same peripherals at boot-time, especially if one is already up. Do I still need Synergy in any case?

Can you tell me what kind of Thunderbolt cable I should be looking for if I want to use the Target Display Mode for the second iMac?

Thanks SO much!
 

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II_to_2020

macrumors newbie
Sep 13, 2020
1
0
@blue_serotta
> Can anyone confirm that this (e.g. Synergy or a KM switch) DOES NOT work?
I can confirm that Synergy does NOT work in all situations. I can also confirm that in September 2020 the refund process is now smooth and immediate. Set up wasn't hard, so it may be worth trying for your situation. But...

There's a bug that randomly repeats keystrokes, including the delete key. Freeze while it ignores inputs, then eight or more inputs of a character you requested once. This Symless-acknowledged bug has existed for SIX years, from v1 to v2 through pulling v2 from the market and reversion to v1. The bug itself is very frustrating, but it's also disappointing that the company thinks it's okay to deliver less than 100% input fidelity in a build described as "stable."

From time to time I also experienced four to five seconds of lag for the cursor to switch screens, mostly when switching from primary to secondary, but not always. There was an even longer delay if Synergy had to wake up the secondary computer.

I used the $40 encrypted version (trying) to share KM across two Retina 5K 27" iMacs, one late-2020, one late-2015, both running Catalina 10.15.6, both w/maxed RAM and the fastest CPU available at time of purchase, both hardwired to the same Gigabit switch on a not-busy network, under all permutations of light and heavy CPU loads.
 
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blue_serotta

macrumors newbie
Apr 5, 2020
3
0
Wow. What a painful journey. It is apparent that deciding between the software switches (e.g., Synergy for example) and hardware option (e.g., Logitech) is loaded with caveats and heartache. @Anonymous Freak mentioned a solution that resonates with my two late 2013 iMacs running Catalina 10.15.7 with my wireless keyboard, mouse and trackpad, to use Logitech’s MX Master 3 and MX Keys Flow-enabled mouse/keyboard for Mac combination. I cannot see how I would have a “seamless” and continuous operation of both iMacs. I cannot see how I can boot up one, then the other, then fire up and use Synergy two iMacs with wireless peripherals. Just sounds like a lot of needless suffering and that Synergy is great for the Mac/iMac/extra monitor/phone crowd——each can boot up by themselves (or just act as an external monitor, not independent machine) and then Synergy works. I’m going to give the Logitech route a try, and pray it all works. I can see how I have to physically configure the Flow-enabled mouse to see one iMac and drive the focus there for my keyboard, then fire up, login, configure the second iMac, mate it with the Logitech mouse/keyboard for say, 2nd position on the mouse, and hopefully both iMacs will be happy sharing, even when they go to sleep. Again, one iMac is already working with existing peripherals, I will need to first use my new combo to mate to iMac 1, then login and setup iMac 2, install Logitech software on that one, too, then it will all work…..seamlessly? :^)
 
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Anonymous Freak

macrumors 603
Dec 12, 2002
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896
Cascadia
If using Logitech option, there are two big caveats:

1. If using Bluetooth, the keyboard doesn't work until you're booted into the OS - so if you have FileVault on, which requires you to type your password pre-OS-boot, you can't use the Logitech keyboard over Bluetooth to type in your password. (Or to do diagnostic startup things like holding Option during boot.) This can be alleviated by using the USB "Unifying Receiver" - unfortunately, it is only USB-A, not USB-C, so you'd have to use a dongle if connecting to an M1 iMac which has no USB-A ports.

2. The devices stay connected to a device until either "Flow" tells it to switch (you can have it so that you just mouse over to one screen edge and it switches to a second computer, or have to hold a key down as you slide to the edge,) or you manually press the buttons on the keyboard and mouse (individually - Flow will switch both, but if you manually switch the mouse or keyboard, it doesn't automatically switch the other one.) This means if the computer you're presently connected to goes to sleep, clicking the mouse or pressing a keyboard key will wake up that computer, not automatically control the second computer.

But other than those two limitations, it is REALLY good. Since the keyboard and mouse make a direct connection to a given computer, it works regardless of which system is on or off. At worst, you need to manually push the "change system" buttons on the keyboard and mouse if you accidentally turn off the "active computer" before switching. (I find I can select "Shut Down" and quickly flick the mouse to the screen edge to have Flow switch systems before the system shuts down.

(Attached video is me demonstrating it, click "Sleep" then IMMEDIATELY fling the mouse to the left - so fast the mouse flung to the far side of the monitor and I had to then bring it back. I have "Hold Ctrl plus hit edge" set, so I hit Ctrl as soon as I selected "Sleep" from the Apple menu.)
 
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