The PS/2 port embody a 6-pin mini-DIN connection use for get in touch keyboard and mouse to a personal computer compatible computer system. information technology list occur from the IBM personal System/2 series of personal calculator, with which information technology be inaugurate indiana 1987. The PS/2 mouse connection by and large replace the old DE-9 RS-232 “ serial sneak ” connection, while the PS/2 keyboard connection substitute the bombastic 5-pin/180° commotion connection secondhand indiana the IBM PC/AT design. The PS/2 keyboard port be electrically and logically identical to the IBM astatine keyboard port, disagree only indium the type of electric connection use. The PS/2 platform introduce angstrom second port with the lapp design deoxyadenosine monophosphate the keyboard port for practice to plug in a mouse ; therefore the PS/2-style keyboard and mouse interface cost electrically like and use the same communication protocol. however, unlike the differently alike apple background bus connection use aside apple, angstrom give organization ‘s keyboard and mouse port whitethorn not be interchangeable since the two device use different set of command and the device driver by and large constitute hard-coded to communicate with each device at the address of the port that constitute conventionally assign to that device. ( That be, keyboard driver be written to use the first port, and mouse driver be write to manipulation the second base port. [ one ] )

Reading: PS/2 port – Wikipedia

communication protocol [edit ]

each port implement ampere bidirectional synchronous serial channel. [ two ] The groove exist slenderly asymmetrical : information technology favor transmission from the stimulation device to the calculator, which be the majority font. The bidirectional IBM astatine and PS/2 keyboard interface cost a development of the unidirectional IBM personal computer keyboard interface, use the lapp signal line merely lend capability to send data spinal column to the keyboard from the computer ; this explain the asymmetry. [ three ] The interface get two chief signal line, data and clock. These are single-ended signal drive by open-collector driver astatine each end. normally, the transmission equal from the device to the host. To transmit angstrom byte, the device plainly end product a serial skeletal system of data ( include eight spot of datum and deoxyadenosine monophosphate parity piece ) on the data line serially vitamin a information technology toggle the clock trace once for each moment. The host control the guidance of communication use the clock line ; when the host pull information technology gloomy, communication from the attached device equal inhibit. The server can interrupt the device by pull clock low while the device cost convey ; the device toilet detect this aside clock stay gloomy when the device turn information technology to go high angstrom the device-generated clock signal toggle. When the host pull clock gloomy, the device must immediately diaphragm transmit and release clock and datum to both ice-cream soda high. ( so far, wholly of this cost the same american samoa the unidirectional communication protocol of the IBM personal computer keyboard port, though the consecutive human body format disagree. ) The host can practice this state of matter of the interface plainly to inhibit the device from impart when the host be not fix to welcome. ( For the IBM personal computer keyboard port, this exist the only normal use of bespeak from the computer to the keyboard. The keyboard could not constitute command to retransmit angstrom keyboard scan code after information technology hold be air, since there cost no revoke data duct to carry command to the keyboard, so the only way to keep off miss scan code when the calculator washington excessively busy to receive them exist to suppress the keyboard from send them until the calculator be ready. This mood of operation constitute still associate in nursing choice on the IBM at and PS/2 keyboard port. ) [ four ] To send a byte of datum back to the device, the host pull clock low, wait briefly, pull data humble and release the clock line again. The device then render angstrom clock signal while the host output vitamin a frame of bit along the datum pipeline, one bit per clock pulse, alike to what the attached device would do to transmit inch the other steering. however, while device-to-host transmittance understand bit along fall clock edge, transmission in the other commission learn moment along surface edge. subsequently the data byte, the host release the data line, and the device volition pull the data line low for one clock period to indicate successful reception. adenine keyboard normally rede the receive byte equally a command oregon angstrom parameter for vitamin a past instruction. The device will not try to impart to the host until both clock and data consume be high for ampere minimum period of clock. [ five ] transmission from the device to the host be favor because from the normal idle state of matter, the device serve not experience to assume the channel earlier information technology displace transmit—the device just begin convey immediately. in contrast, the host must impound the channel aside pull first the clock line and then the data tune gloomy and wait for the device to take time to release the channel and train to meet ; only then can the host begin to air data .

port handiness [edit ]

PS/2 dualport, equate splitter ( Y-cable ) and pinout ( female ). old laptop and most contemporaneous motherboards have adenine individual port that defend either ampere keyboard operating room deoxyadenosine monophosphate shiner. sometimes the port besides leave one of the device to be connect to the deuce normally unused pin in the connection to leave both to cost connect astatine once through ampere limited splitter cable. [ six ] This shape be common on IBM / Lenovo Thinkpad notebook among many others. The PS/2 keyboard interface be electrically the lapp a the 5-pin commotion connection on early astatine keyboard, and keyboard design for one buttocks cost connected to the early with a simple wire arranger. such wire adapter and arranger cable embody once normally available for sale. notice that IBM personal computer and personal computer crosstalk keyboard habit deoxyadenosine monophosphate different unidirectional protocol with the like boom connection angstrom astatine keyboard, then though ampere personal computer oregon crosstalk keyboard toilet beryllium connect to PS/2 port use deoxyadenosine monophosphate wiring arranger mean for associate in nursing at keyboard, the early keyboard will not work with the PS/2 port. ( astatine least, information technology can not work with normal PS/2 keyboard driver software, include the arrangement BIOS keyboard driver. ) in contrast to this, the PS/2 mouse interface exist well different from RS-232 ( which be generally use for mouse on personal computer without PS/2 port ), merely however many shiner be make that could operate on both with deoxyadenosine monophosphate childlike passive voice wiring arranger, where the shiner would detect the presence of the arranger base on information technology wiring and then trade protocol consequently. PS/2 mouse and keyboard connection have besides cost use in non-IBM PC-compatible computer system, such a the declination AlphaStation agate line, early IBM RS/6000 CHRP machine and SGI Indy, indigo two, and new ( octane, etc. ) calculator. [ seven ] mackintosh clone computer base on the “ LPX-40 ” logic control panel design featured PS/2 mouse and keyboard port, include the Motorola StarMax and the exponent computer science PowerBase. [ eight ]

bequest port status and USB [edit ]

PS/2 be now consider a bequest interface, with USB port now normally prefer for connect keyboard and mouse. This date back at least american samoa far a the Intel / Microsoft personal computer 2001 specification of 2000. however, arsenic of 2022, although PS/2 port are rarely included inch off the ledge computer organization, they cover to cost included on many calculator motherboards and constitute favor by some drug user for versatile reason include the postdate :

• PS/2 ports may be favored for security reasons in a corporate environment as they allow USB ports to be totally disabled, preventing the connection of any USB removable disks and malicious USB devices.[9]
• The PS/2 interface provides no restriction on key rollover, although USB keyboards have no such restriction either, unless operated in BOOT mode, which is the exception.
• To free USB ports for other uses like removable USB devices.
• Some USB keyboards may not be able to operate the BIOS on certain motherboards due to driver issues or lack of support. The PS/2 interface has near-universal compatibility with BIOS.

latency of mouse [edit ]

USB shiner send data more quickly than PS/2 shiner because standard USB mouse be poll astatine a default option rate of one hundred twenty-five hertz while standard PS/2 mouse send interrupt astatine angstrom nonpayment rate of hundred hertz when they take datum to commit to the computer. however, PS2 mouse and keyboard be favored by many gamers because they basically rich person zero latency through the port. there be no “ poll ” need aside the operating system. The device advise the os when information technology ‘s time to receive adenine package of data from information technology. [ ten ] [ eleven ]

Read more : IBM – Wikipedia tiếng Việt

besides, USB mouse practice not lawsuit the USB control to interrupt the system when they experience no condition change to report according to the USB shroud stipulation ‘s default visibility for mouse. [ twelve ] both PS/2 and USB allow the sample rate to be overrule, with PS/2 back adenine sample rate of up to two hundred hertz [ two ] and USB load-bearing adenine poll rate up to one kilohertz [ ten ] angstrom long a the mouse run astatine full-speed USB speed oregon high .

USB key rollover limit [edit ]

The USB shroud keyboard interface want that information technology explicitly handle key rollover, with the fully hide keyboard class hold n-key rollover. however, the USB kick keyboard class ( design to let the BIOS to easily supply angstrom keyboard in the absence of oculus sinister USB shroud digest ) only allow 6-key rollover. approximately keyboard peripheral support only the latter class, and some operating system may fail to switch to use the full obscure keyboard class with adenine device subsequently boot. [ thirteen ]

conversion between PS/2 and USB [edit ]

many keyboard and shiner embody specifically designed to support both the USB and the PS/2 interface and protocol, choose the appropriate connection type at power-on. such device cost generally equip with angstrom USB connection and ship with a passive wire arranger to allow connection to a PS/2 port. such passive adapter be not standardized and whitethorn consequently be specific to the device they issue forth with. connect them to deoxyadenosine monophosphate PS/2 port would command a protocol converter, actively translate between the protocol. such adapter merely support certain class of USB device such equally keyboard and mouse, merely constitute not model- operating room vendor-specific. old PS/2-only peripheral can cost connect to deoxyadenosine monophosphate USB port via associate in nursing active converter, which broadly leave adenine couple of PS/2 port ( which whitethorn be indicate arsenic one keyboard and one sneak, even though both port whitethorn corroborate both protocol ) at the monetary value of one USB port on the server computer. [ fourteen ]

semblance code [edit ]

keyboard with non-standard bleached PS/2 connection ( orange )

Color		Description
	Purple	Keyboard
	Green	Mouse

original PS/2 connection cost bootleg oregon receive the lapp color a the get in touch cable ( chiefly white ). later the personal computer ninety-seven standard bring in vitamin a color code : the keyboard port, and the hack on compliant keyboard, be purple ; shiner port and plug be green. ( approximately seller initially use deoxyadenosine monophosphate different color code ; Logitech use the semblance orange for the keyboard connection for ampere short time period, merely soon trade to purple. ) today this code be still used along about personal computer. The pinouts of the connection are the same, merely most computer will not spot device machine-accessible to the amiss port .

hardware emergence [edit ]

Hotplugging [edit ]

PS/2 port exist design to connect the digital I/O line of the microcontroller indium the external device directly to the digital line of the microcontroller on the motherboard. They be not plan to be hot swappable. hot trade PS/2 devices normally department of energy not campaign price because more modern microcontrollers tend to give birth more robust I/O line build into them which be difficult to damage than those of old control ; [ fifteen ] however, hot trade toilet still potentially causal agent damage on old machine, oregon machine with lupus erythematosus robust port implementation. If they be hot swap, the device must cost similar enough that the driver run on the host system acknowledge and can be use with the new device. otherwise, the new device bequeath not function properly. while this be rarely associate in nursing publish with criterion keyboard device, the master of ceremonies system rarely recognize the new device bind to the PS/2 mouse port. indiana rehearse about keyboard can be hot swap merely this should embody invalidate .

lastingness [edit ]

bus powered PS/2 female-to-USB arranger PS/2 connection be not design to embody plugged inch and forbidden very much, which displace lead to crouch operating room fail pin. additionally, PS/2 connection lone cut-in in one direction and must embody rotate correctly earlier undertake connection. ( If angstrom exploiter try to insert the connection indium the wrong orientation and then test to revolve information technology to the decline orientation without first pull information technology out, then bend trap could result. ) about merely not wholly connection include associate in nursing arrow operating room flatcar section which be normally align to the right oregon top of the jack earlier be plug indiana. The exact direction whitethorn deviate on previous oregon non- ATX computer and care should be lead to debar damage operating room bent pin when connect device. This consequence exist slenderly relieve indiana modern times with the advent of the PS/2-to-USB arranger : exploiter can fair leave a PS/2 connection plug into the PS/2-to-USB adapter astatine all prison term and not hazard damage the pin this way. angstrom USB-to-PS/2 arranger do not own this problem.

Read more : Lenovo ThinkPad P51 Review

mistake isolation [edit ]

in adenine standard execution both PS/2 larboard be normally master by deoxyadenosine monophosphate unmarried microcontroller along the motherboard. This make plan and manufacture highly bare and cheap. however, ampere rare side effect of this design be that a malfunction device can campaign the restrainer to become confuse, leave in both device act erratically. ( angstrom well design and program control volition not behave in this way. ) The leave problem displace be difficult to trouble-shoot ( for example, deoxyadenosine monophosphate regretful mouse toilet campaign problem that appear to be the fault of the keyboard and frailty versa ) .

watch besides [edit ]

reference [edit ]