Post subject: How to handle a single PS/2 port?
Emulator Coder
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I have a computer with a motherboard which only has a single PS/2 port on it. It's kind of annoying when you want to use DOS or something else old with no USB support, and want both a keyboard and mouse present. I see they sell these PS/2 Y Cables (splitters) which allow two PS/2 devices share a single port. But I see lots of people who order these online complain in customer feedback that its incompatible with their motherboard. Is there any way to know in advance if the motherboard will support one of these? Are these more compact designs just lazy, and the motherboard itself really supports another PS/2 jack connector, if they were both soldered on properly? Anyone have wisdom on this matter? Thanks.
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Sorry, no wisdom, but I'm thinking that motherboards (at least if you buy them yourself rather than bying a pre-assembled PC) often come with additional optional parts (such as game/joystick ports, etc). I suppose you have checked that yours didn't come with such a splitter already.
Tub
Joined: 6/25/2005
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y-cables are nonstandard, if your motherboard supports them you could expect a) that the feature is documented / advertised b) that a suitable y-cable is either included or available directly from the mobo-vendor, because they aren't standardized either. You could check whether Pin 6 carries any voltage (if you have the equipment). Otherwise you just may have to buy the cable and try.
m00
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There is also this option for old skool DOS. http://cgi.ebay.com/Microsoft-9-pin-Serial-Mouse-Used-Clean-Free-S-H-/400209247468?pt=Mice&hash=item5d2e547cec If the computer is as old as I'm assuming, then it probably has a serial port on it. Man, this brings back memories of playing inside AUTOEXEC.BAT and CONFIG.SYS, trying to get things to work. FILES = 40!!!! Still no idea what that meant.
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Editor
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It means to allocate memory for 40 file open state structures. Because apparently ms dos was too stupid to allocate those on demand.
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Tub wrote:
y-cables are nonstandard, if your motherboard supports them you could expect a) that the feature is documented / advertised b) that a suitable y-cable is either included or available directly from the mobo-vendor, because they aren't standardized either.
Interesting, I heard opposing opinions elsewhere. Is there any truth to mice and keyboards being wired differently? The motherboard documents that it works for both mouse and keyboard, but doesn't specify if whether that's at the same time or not.
DarkKobold wrote:
There is also this option for old skool DOS. http://cgi.ebay.com/Microsoft-9-pin-Serial-Mouse-Used-Clean-Free-S-H-/400209247468?pt=Mice&hash=item5d2e547cec
I own an old MS Home Mouse with a serial connector.
DarkKobold wrote:
If the computer is as old as I'm assuming, then it probably has a serial port on it.
The motherboard is about 1.5 years old, not sure why you're assuming anything here. There is no serial port.
DarkKobold wrote:
Man, this brings back memories of playing inside AUTOEXEC.BAT and CONFIG.SYS, trying to get things to work. FILES = 40!!!! Still no idea what that meant.
How many files should you be allowed to open at once under various conditions.
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Emulator Coder
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I'm wondering how accurate and up to date that Wikipedia article is. Back in 2002, I mistakenly mixed up the keyboard and mouse when plugging them in, and was surprised to see it working anyway, when it did not on older machines. Since then, I've swapped them on at least a dozen machines, as well as hot swapped mice without any issues at all. I don't know what to believe... I've used motherboards from Asus, MSI, Gigabyte, and ABit that all behaved like I just described. I also see various companies putting out splitters: http://www.amazon.com/StarTech-Keyboard-Splitter-Adapter-KYC1MF/dp/B000067SLZ/ref=sr_1_1?ie=UTF8&qid=1302706529&sr=8-1 http://www.amazon.com/QVS-CC321Y-Keyboard-Mouse-Splitter/dp/B00007E85M/ref=sr_1_3?ie=UTF8&qid=1302706529&sr=8-3 http://www.amazon.com/6In-PS2-Keyboard-Mouse-Y-Splitter/dp/B004LCGBPQ/ref=sr_1_7?ie=UTF8&qid=1302706529&sr=8-7 http://www.amazon.com/Cables4PC-LAPTOP-MOUSE-KEYBOARD-SPLITTER/dp/B000U64YLU/ref=sr_1_16?ie=UTF8&qid=1302706529&sr=8-16 But the comments seem that it sometimes works and it sometimes doesn't.
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Nach wrote:
Since then, I've swapped them on at least a dozen machines, as well as hot swapped mice without any issues at all. I don't know what to believe...
AFAIK the technical specification of the PS/2 port doesn't require support for hot-swapping, and I assume that the oldest and cheapest motherboards had no safety measures against it, so you could potentially damage the circuit, and even in the best cases the system would not detect the swapping. Better motherboards probably have safety measures to avoid this, even if the standard doesn't require it.
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Warp wrote:
Nach wrote:
Since then, I've swapped them on at least a dozen machines, as well as hot swapped mice without any issues at all. I don't know what to believe...
AFAIK the technical specification of the PS/2 port doesn't require support for hot-swapping, and I assume that the oldest and cheapest motherboards had no safety measures against it, so you could potentially damage the circuit, and even in the best cases the system would not detect the swapping. Better motherboards probably have safety measures to avoid this, even if the standard doesn't require it.
And every motherboard I worked with which came out in the past decade or so seems to be the latter kind...
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arflech
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IIRC the two external PS/2 ports go to the same part of the motherboard internally; for this reason, sometimes apparent errors with the mouse are actually errors with the keyboard and vice-versa.
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Nach wrote:
The motherboard is about 1.5 years old, not sure why you're assuming anything here. There is no serial port.
I guess I figured PS2 port + dos = old. Hence why I called it an assumption.
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DarkKobold wrote:
Nach wrote:
The motherboard is about 1.5 years old, not sure why you're assuming anything here. There is no serial port.
I guess I figured PS2 port + dos = old. Hence why I called it an assumption.
Having just a single PS/2 port on a machine (outside of laptops, and given there are PS/2 ports at all) is a rather recent phenomenon. I think it started ~2-3 ago. Interestingly enough though, I found that my motherboard has a header for a serial port...
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