2/25/2017 new driver models for direct download:591
Ring 4012pm 150dpi 5 stars review"The best driver WIKI ever! I wil keep coming back for sure."Eric Smalter, Boston, MA
Supported languages for Ring 4012pm 150dpi
Certifications for Ring 4012pm 150dpi
5 stars for Ring 4012pm 150dpi "WOW! Finally my PC got up to speed!" Melany Kim 7/18/2015

Checking...for 2/25/2017 Updates

All drivers on are updated on daily basis.

However, a new version of Ring 4012pm 150dpi might have been uploaded since our last site update.

Ring 4012pm 150dpi Driver Download

Windows Compatibility for Ring 4012pm 150dpi driver

Ring 4012pm 150dpi Driver Details:

Ring 4012pm 150dpi File Name:

Ring 4012pm 150dpi Driver Version: 90593

Ring 4012pm 150dpi ZIP Size: 111.kb

Manufacturer: Ring

Ring 4012pm 150dpi was fully scanned at: 2/23/2017
Scan Status: driver download scanOK

Ring 4012pm 150dpi special revision for: Windows XP Media Center Edition 2005 32 bit, Windows 10 64 bit, Windows 7 Service Pack 1 (Microsoft Windows NT) 64 bit, Windows Vista Business 32 bit, Windows XP Media Center Edition 2004 32 bit, Windows XP Home Edition, for home desktops and laptops 64 bit, Windows XP 64-bit Edition 32 bit

Ring 4012pm 150dpi Download Stats:

Driver Uploaded: 2/8/2017

Direct Downloads: 561
Most Recent Download: 2/23/2017
Managed Downloads: 6635
Most Recent Download: 2/23/2017
Download Mirrors: 5
Current Delay: 15 Seconds
Driver License: Free

Direct Download Success Stats:

Reports Issued By 482/561 Users

Success Reported By 138/482 Users

Driver Download Score67/100

Driver Installation Score63/100

Overall preformance Score61/100

Ring 4012pm 150dpi 16 Thumbs Up16Thumbs
Ring 4012pm 150dpi 3 Thumbs Down3Thumbs
Ring 4012pm 150dpi driver direct download was reported as adequate by a large percentage of our reporters, so it should be good to download and install.

Installation Manager Success Stats:

Reports Issued By 5738/6635 Users

Success Reported By 4778/5738 Users

Driver Download Score94/100

Driver Installation Score91/100

Overall preformance Score91/100

Ring 4012pm 150dpi 4585 Thumbs Up4585Thumbs
Ring 4012pm 150dpi 212 Thumbs Down212Thumbs
Ring 4012pm 150dpi driver installation manager was reported as very satisfying by a large percentage of our reporters, so it is recommended to download and install.


1. Direct Download

Select your OS and press "Download".

This option requires basic OS understanding.
Select Your Operating System, download zipped files, and then proceed to
manually install them.
Recommended if Ring 4012pm 150dpi is the only driver on your PC you wish to update.


2. Driver Installation Manager

This option requires no OS understanding.
Automatically scans your PC for the specific required version of Ring 4012pm 150dpi + all other outdated drivers, and installs them all at once.

Please help us maintain a helpfull driver collection.
After downloading and installing Ring 4012pm 150dpi, or the driver installation manager, take a few minutes to send us a report:
* Only registered users can upload a report.

Don’t have a password?
Please register, and get one.

Ring 4012pm 150dpi may sometimes be at fault for other drivers ceasing to function

These are the driver scans of 2 of our recent wiki members*

*Scans were performed on computers suffering from Ring 4012pm 150dpi disfunctions.

Scan performed on 2/25/2017, Computer: Panasonic CF-53AAC01FD

Outdated or Corrupted drivers:8/19

Device/DriverStatusStatus DescriptionUpdated By Scanner
Intel(R) QPI Physical 0 - 2C91Corrupted By Ring 4012pm 150dpi
Mice And Touchpads
Synaptics Synaptics PS/2 Port TouchPadUp To Date and Functioning
Usb Devices
Logitech Logitech USB Camera (IM/Connect)Up To Date and Functioning
Motorola Mot Composite ADB InterfaceCorrupted By Ring 4012pm 150dpi
Sound Cards And Media Devices
DisplayLink DisplayLink USB Audio AdapterUp To Date and Functioning
NVIDIA NVIDIA High Definition AudioUp To Date and Functioning
Network Cards
Cologne Chip AG, Billion Electric Network ControllerCorrupted By Ring 4012pm 150dpi
Microsoft Keyboard Device FilterUp To Date and Functioning
Hard Disk Controller
Ricoh Ricoh Memory Stick Bus Host AdapterOutdated
Intel(R) ICH9DO LPC Interface Controller - 2914Corrupted By Ring 4012pm 150dpi
Microsoft Texas Instruments PCI-xx21/xx11 CardBus Controller with UltraMediaCorrupted By Ring 4012pm 150dpi
Intel(R) Sensor SolutionCorrupted By Ring 4012pm 150dpi
Google Android ADB InterfaceCorrupted By Ring 4012pm 150dpi
Cameras, Webcams And Scanners
Canon Canon MP600RUp To Date and Functioning
Video Cards
NVIDIA NVIDIA GeForce GT 630MUp To Date and Functioning
Input Devices
Microsoft HID-compliant consumer control deviceUp To Date and Functioning
Port Devices
PROLiNK PROLiNK UI AT Interface (COM7)Up To Date and Functioning
Sony Digital Flat Panel (1024x768)Up To Date and Functioning
Mobile Phones And Portable Devices
Acer NOKIAUp To Date and Functioning

Scan performed on 2/25/2017, Computer: Toshiba Dynabook C7212CMHN

Outdated or Corrupted drivers:10/20

Device/DriverStatusStatus DescriptionUpdated By Scanner
Microsoft ATI E/A-Kommunikationsprozessor-LPC-ControllerCorrupted By Ring 4012pm 150dpi
Mice And Touchpads
Logitech HID mouseCorrupted By Ring 4012pm 150dpi
Usb Devices
Microsoft EPSON Epson Stylus SX130 SeriesUp To Date and Functioning
Sound Cards And Media Devices
China USB2.0 Video CaptureUp To Date and Functioning
AMD ATI Function Driver for High Definition Audio - ATI AA01Outdated
Network Cards
Realtek ASUS USB-N13 300Mbps 11n Wireless USB dongleUp To Date and Functioning
Microsoft Keyboard Device FilterCorrupted By Ring 4012pm 150dpi
Hard Disk Controller
NVIDIA NVIDIA MCP51 Parallel ATA ControllerUp To Date and Functioning
Datel Design & Development DSi AR HW ProgUp To Date and Functioning
Intel Intel(r) AIM External Flat Panel Driver 3Corrupted By Ring 4012pm 150dpi
Nokia Nokia USB PhonetCorrupted By Ring 4012pm 150dpi
Hewlett-Packard psc 1200 (USBPRINT)Up To Date and Functioning
AuthenTec Biometric CoprocessorUp To Date and Functioning
Intel Intel(r) AIM External TV Encoder Driver 2Up To Date and Functioning
Cameras, Webcams And Scanners
Canon CanoScan LiDE 110Corrupted By Ring 4012pm 150dpi
Video Cards
ATI ATI Technologies, Inc. 3D RAGE PRO AGP 2XUp To Date and Functioning
Input Devices
Logitech USB Input Device (Logitech Download Assistant)Up To Date and Functioning
Port Devices
D-Link USB Single PortCorrupted By Ring 4012pm 150dpi
Sony Digital Flat Panel (1024x768)Outdated
Mobile Phones And Portable Devices
Acer NOKIACorrupted By Ring 4012pm 150dpi
Driver ModelOriginal Upload DateLast ModificationDriver FileFile SizeCompatible Computer ModelsAvailabilty To Instalation Manager
Ring 4012pm 150dpi H2244211/11/201412/30/2016ring_4012pm_150dpi-h22442.exe102kbAcer Acer 8935G, Panasonic CF-53AAC28FG, NEC PC-MJ18XAZEZXS9, NEC PC-MK31MEZCE, Fujitsu D3161-B1, Sony VGN-FW140AE, Lenovo ThinkPad X230 Tablet, LG A510-U.AESGE2, LG G1-223YA2, NEC PC-GV287UZGN, HP HP Compaq nc4200, Gateway FX4710-UB802A, and more.
Ring 4012pm 150dpi W71.18601/6/201512/29/2016ring_4012pm_150dpi-w71.1860.exe127kbCompaq Presario 7RPM11 195749-999, Intel Test Product, Panasonic FZ-G1AAHJXRM, Fujitsu M6VCG, Compaq GN666AA-ABM SG3102LA, HP Pavilion dv9000, Lenovo ThinkCentre M90, ICP / IEi IMBA-Q454, NEC PC-GV286VZAU, Fujitsu N6220, IBM IBM System x3400 M3 Server -[7379KFG, BYON CHAMELEON, IBM IBM System x3350 -[4193E5G, HP Pav dv6653 ares, NEC PC-MY26LEZ78, Compaq PX700AA-ABZ SR1449IT IT520, IBM IBM System x3400 M3 Server -[7379Z7X, and more.
Ring 4012pm 150dpi 3036411/9/201412/29/2016az-30364.exe203kbHP HP D290 MT, HP PS414AA-AB5 W1268HK, WIPRO WNB7PHC4700-0002, Packard Bell IMEDIA B2218 UK, BenQ Joybook S72, Gigabyte T1005, Fujitsu FMVLX60W, Foxconn Inferno Katana GTI, GETAC P470, Sony VGN-FW5ZRF_H, LG LW75-SGGV3, Sony VGN-CS16G_R, Sony VGN-P45GK_W, Compaq ER922AA-ABA SR1834NX NA661, and more.
Ring 4012pm 150dpi 822668/29/201412/27/2016fupokcziw-82266.exe32kbPanasonic CF-C1BEAADR, Toshiba SATELLITE C855-1X3, Dell PowerEdge R410, Lenovo 20B00006MZ, Sony VGN-NS160D, Sony VGN-TT1, IBM 6204EBC, Lenovo ThinkPad X200, LG LW40-J4JE2, Intel D965MTW, MSI MS-9179, AOpen MP65, HP 500-108eo, Medion MS-7667, SAMSUN R710, Acer Veriton M460/S460, Sony PCG-GRX700, and more.
Ring 4012pm 150dpi C2.13671.110/2/201412/30/2016ring_4012pm_150dpi-c2.13671.1.exe56kbHP Presario V5000, Compaq EG215AA-ABG SR1660AN AN540, Sony VPCZ12X9R, Packard Bell IMEDIA D9351 AIO, HP GU519AA-UUW, Toshiba SATELLITE PRO C850-19G, NEC PC-MJ30VEZE1, Packard Bell OneTwo S3221, Supermicro X7QC3, Sony VPCW21S1R, and more.
Ring 4012pm 150dpi D2.1006812/30/201412/27/2016ring_4012pm_150dpi-d2.10068.exe92kbToshiba Satellite P870, Sony VGN-NS15G_S, EMachines EMachines G420, IBM 8113WSU, MouseComputer Z68A-SD60, HP KE485AA-UUZ, Toshiba NB300-10D, IBM System x3650 M3 -[7945AC1, Sony VGN-FZ290FU, Toshiba Satellite C850-B843, HP G5144fr-m, Acer Veriton M460/S460, HP KT541AA-UUB a6528hk, IBM ThinkPad T43, Sony VGC-JS92JS, Lenovo ThinkPad T430s, and more.
Ring 4012pm 150dpi W629792/4/201512/30/2016ring_4012pm_150dpi-w62979.exe38kbToshiba DynaBook V7, HP GG685AA-ABF a6117.f, Lenovo 20ANCTO1WW, TAROX Business 5000BM, HP 3639, Gateway 06DT048, Compaq EG735AA-ABH SR1560NL NL530, HP PN133AA-ABU, HP Rfrb h8-1100z, LG R510-S.AP87K, HP FL399AA-ABZ m9495it, Gateway GT5228J, IBM ThinkCentre A50p, Sony PCG-GRX700, NEC PC-LG17FWTGG, HP FJ470AAR-ABA m9357c, Toshiba SATELLITE C55-A-16Z, Medion P861X, Gericom Phantom, and more.
Ring 4012pm 150dpi P1.133442/18/201512/27/2016ring_4012pm_150dpi-p1.13344.exe135kbHP EZ090AA-ACP, HP HP Compaq nc6400, Toshiba SATELLITE C855D-122, NEC PC-VC5002D, LG R200-D.CPF1A9, Lenovo 7659V26, Compaq Evo N610c, IBM 1872W5A, HP Pavilion zd7000, LG LW65-KDTRV, LG R200-D.CPF1A9, LG R560-CR20K, Sony VPCF13NFX, Samsung SQ45/Q70C/P200, HP HP Compaq 8710p, and more.
Ring 4012pm 150dpi 31.122912/26/201412/30/2016ring_4012pm_150dpi-31.1229.exe42kbASUS R052CE, HP FL422AA-ABT a6613is, Sony VGN-TZ330E, HP PS414AA-AB5 W1268HK, LG E500-S.AP22R1, HP Pavilion P6640F ABC, Acer A0A150, HP 200-5410es, Acer Aspire 1425P, Sony VGN-SZ79GN_C, LG XNOTE, ALFATRON SpA DN1020/M, LG R500-U.CPCIT, Fujitsu FMVXD4VR2Z, HP HP 655 Not3book PC, LG R590-PR70K, and more.
Ring 4012pm 150dpi V2.12692.18/24/201412/27/2016ring_4012pm_150dpi-v2.12692.1.exe149kbFujitsu FMVNFC60H, Transource Computer Systems, Toshiba SATELLITE C855-23Z, Lenovo ThinkPad W520, HP PN133AA-ABU, Acer NC-V5-571P-53338G75MASS, Gateway GT4228m, Compaq DA309A-B14 6540. BE910, Panasonic CF-30C4TAABM, HP NM953AA-UUW p6054sc, Toshiba SATELLITE C870D-116, SAMSUN Q308, Acer Aspire 1820, , Fujitsu CELSIUS W370, Shuttle SD10, IBM ThinkCentre M52, KOHJINSHA APERA Series, Acer Aspire M5800, and more.
Ring 4012pm 150dpi 61.19291/22/201512/28/2016ring_4012pm_150dpi-61.1929.exe58kbDell OptiPlex 760, MSW GmbH & Co. KG Intel DP55WB, Compaq VN469AA-UUZ CQ5235CH, Sony VPCCW29FS, Sony VGN-FJ78SP_W, Fujitsu PRIMERGY TX140 S1, Toshiba Dynabook T350/34BBM, IBM 8212K4U, IBM 812235U, Lenovo 2756AF8, Lanix LANIX CORP 4030, and more.
Ring 4012pm 150dpi 23961.12/2/201512/30/2016ring_4012pm_150dpi-23961.1.exe169kbIBM IBM System x3400 M3 Server -[7379KFG, BYON CHAMELEON, IBM IBM System x3350 -[4193E5G, HP Pav dv6653 ares, NEC PC-MY26LEZ78, Compaq PX700AA-ABZ SR1449IT IT520, IBM IBM System x3400 M3 Server -[7379Z7X, Sony VGN-CS26G_P, Toshiba SATELLITE C850-A791, LG LW70-QJMA, HP HP Compaq dx6120 MT, NEC EASYNOTE PB47Q01806, and more.
Ring 4012pm 150dpi U62271.110/6/201412/29/2016ring_4012pm_150dpi-u62271.1.exe160kbSony PCG-GR5F_BP, HP EP127AA-ABD a123l, HP KQ519AA-ABU, ASUS M50V, Acer Aspire 5672, Toshiba Dynabook Qosmio G10/390LS, Sony VPCF13BFX, NEC PC-VY17MRFEAEH1, EMachines 98.Y2D7Z.CF0, Compaq FQ552AA-ABA SR5616F, Sony VGN-G11XRN_B, PCP+ G41 Xeon series, NEC PC-VK26MDZCE, Fujitsu FMVNFA55K, and more.
Ring 4012pm 150dpi 6320610/29/201412/29/2016frpzjodu-63206.exe176kbDell S5400SF, Panasonic CF-S9LWGJDS, Fujitsu CELSIUS W380, Panasonic CF-53JAWZYDE, Compaq PJ517AA-ABA SR1220NX NA441, Sony VPCCW1IGX, LG R405-A, IBM 8212W4R, Seneca Pro354493, Compaq RZ569AA-ABZ SR5039IT, and more.
Ring 4012pm 150dpi 41.193812/22/201412/29/2016ring_4012pm_150dpi-41.1938.exe109kbASUS R052CE, Toshiba Satellite Pro 6100, Gateway M-7332H, Seneca PRO102698, HP Pavilion ZV6100, MSI GR620, Gateway P-171X FX, Gateway 564GE, HP HP D290 MT, Lenovo ThinkPad T420, Sony VGN-FE52B_H, LG X200-L.AGFLZ, IBM 217163G, and more.
Ring 4012pm 150dpi 2.1021.1212/13/201412/30/2016ring_4012pm_150dpi-2.1021.12.exe192kbAcer MX4SG-4DL, Toshiba SATELLITE C850-A819, Fujitsu D2804-A1, HP BN496AV-ABA HPE-170t, LG S1-P655R1, LG K1-2249A9, Gigabyte H61M-USB3-B3, Pinnacle C5108, MSI IR-7529, ASUS Z9PE-D16 Series, WIPRO WIV37455-0653, Dell Vostro 5470, Panasonic CF-19MH207NW, Fujitsu LifeBook A6210, HP PAVILION DV6187, and more.
Ring 4012pm 150dpi K378410/22/201412/30/2016ring_4012pm_150dpi-k3784.exe216kbToshiba SATELLITE C850-A817, HP EL521AA-AB1 a1329k, HP 110-009el, MSI U4-7302, Sony VGN-SZ6RXN_C, Toshiba Dynabook R731/W2MB, HP HP Pavilion zt3000, HP HPE-430it, Panasonic CF-52RE401QW, Lenovo 6458Y6X, Supermicro SYS-5017C-MF, Sony PCV-RS221, Dell Inspiron 20 Model 3045, IBM IBM eServer m Mem-[7976KJG, Toshiba Dynabook Satellite AW2, Toshiba Dynabook TX/66GPKJ, NEC PC-GL24ES8DE, MSI MS-7360, and more.
Ring 4012pm 150dpi NetVista personal computer, Compaq Presario 6266EA, Sony VGN-A195EP, Toshiba SATELLITE C855-12Z, Sony PCG-FX602, HP RJ788AA-ABA a1613w, Lenovo 20AMS05C00, Compaq DA255A-ABA 6401RSH NA910, HP P6563sc, Packard Bell IPower X1001, MIKROLOG S800SE-C6, Sony VGN-AW25GJ_H, MAXDATA PLATINUM 100 I M5, IBM IBM eServer 206m -[8485PEE, HP RR492AA-ABE, Toshiba SATELLITE L870-16L, Acer Acer 8935G, Compaq NC760AA-AB4 SR5780AP, and more.
Ring 4012pm 150dpi 2.1369911/22/201412/30/2016ring_4012pm_150dpi-2.13699.exe65kbDell Latitude 13, NEC PC-GV267VZDL, Intel SJR2A092, Gigabyte 7GEWH, HP GG698AA-ABH, Lenovo ThinkStation D20, Fujitsu LifeBook A6030, Sony VPCF13S0E, Gateway P-171X FX, Sony VPCEB19GX, Sony VPCEB3S1E, Lenovo 7659WH9, Gateway GM5632E, HP S5-1021p, HP ES131AA-UUZ, Notebook MIM2280, Gateway P-7803h, Gigabyte Z97X-UD5H, Toshiba SATELLITE L850-A892, and more.
Ring 4012pm 150dpi 41.16333/4/201512/30/2016ring_4012pm_150dpi-41.1633.exe150kbHP P6520ch-m, IBM 622351U, Fujitsu LifeBook N6470, ASUS CG5290, HP 3082, LG S1-M402E1, Toshiba Dynabook EX1/524CDE, HP KJ325AA-ABG a6440a, I-MOBILE TPC-2A, HP P8264A-ABF 761, Lenovo ThinkPad SL300, and more.
Ring 4012pm 150dpi X71.198210/17/201412/27/2016ring_4012pm_150dpi-x71.1982.exe58kbToshiba Qosmio D730, Toshiba Dynabook T451/58EBS, Toshiba Satellite C850-B820, Lenovo 20AMS05C00, HP HPE-280jp, SIEMENS SIMATIC IPC627C, NEC PC-MY26XHZE1, HP PX635AA-ABU, HP PS227AA-ABE, NEC PC-GV287UZGN, Panasonic CF-18KHVCBBF, and more.
Ring 4012pm 150dpi 2.102891/22/201512/30/2016ring_4012pm_150dpi-2.10289.exe162kbLG LW75-SGGV3, Sony VGN-CS16G_R, Sony VGN-P45GK_W, Compaq ER922AA-ABA SR1834NX NA661, IBM 8215VFZ, HP GS210AA-ABV dx2290MT, Sony VGN-AW190Y, EMachines Emachines D525, LG X200-NS5BK, LG P1-J455R, HP GJ345AA-UUW, Fujitsu FMVS54KRC, HP 810-150se, and more.
Ring 4012pm 150dpi 1.12241.13/1/201512/28/2016ring_4012pm_150dpi-1.12241.1.exe213kbSony VGN-SZ2HP_B, GETAC V100-X, HP GX609AAR-ABA m9160f, HP ES116AA-B14, HP NM943AA-UUW m9570, HP GX610AAR-ABA m9180f, Compaq NQ905AA-ABU CQ5012UK, HP FK557AAR-ABA a6602f, IBM System x3200 M3 -[7328AC1, SAMSUN NP-R510-FS04NL, Compaq DQ119A-ABZ S5400IT IT340, ITSUMI ADAX, Fujitsu FMVNXA90N, NEC PC-LL550KG1J, HP M8417c-ABA m8417c, and more.
Ring 4012pm 150dpi 3348012/2/201412/27/2016ring_4012pm_150dpi-33480.exe162kbIBM IBM x3850-[88632RU, LG LB50-CC34ZL, Sony VGN-NS130AE, NEC PC-VN470GS6R, Seneca Pro234499, NEC PC-VJ24LLNVHT8B, VMware VMware7,1, Packard Bell IMEDIA MC 9330, IBM 6792GGU, Gericom Phantom, MCJ P55-SD, and more.
Ring 4012pm 150dpi 403262/20/201512/28/2016nflzxi-40326.exe113kbHP EP074AA-ABU, Panasonic CF-19KHRC62B, Fujitsu FMVF77DDRC, Sony VGN-SZ77N_C, Crea NW SERIES, MSI VR321, Sony VGN-SZ7RMN_B, HP PW774AA-ABE, Seneca Pro64601, HP 520-1000pt, HP HP Pavilion zd7000A, LG Z1-B821P1, Toshiba Dynabook TX/67J2PKYD, HP PN133AA-ABU, and more.
Ring 4012pm 150dpi 1.1377011/12/201412/30/2016-1.13770.exe215kbIntel S1200RP_SE, Packard Bell IMEDIA F5750, Fujitsu FMVLX70WDJ, HP HP EliteBook 6930p Notebook PC, Sony PCG-TR3_B, HP VN294AA-UUZ p6210ch, HP ED737AA-ABS, Toshiba SATELLITE U50-A, NEC PC-LL750GD1K, HP 700-150ef, HP Pavilion ZV6000, IBM IBM IntelliStation M Pro -[922962J, and more.
Ring 4012pm 150dpi M61.137712/14/201412/29/2016ring_4012pm_150dpi-m61.1377.exe157kbHP NQ867AA-UUZ m9650ch, Lanix Lanix Corp, Fujitsu LifeBook T4310, Compaq PS245AA-ABF SR1339FR FR510, HP KQ265AA-AB4 s3385d, AnabelleB Argyle M261V, HP RY889AA-UUW, LG X110-L.A7SPE, Supermicro C2SBC-Q, BenQ Joybook A51, Apple Macmini1,1, Panasonic CF-SX1WEUHR, Packard Bell EasyNote TM01, IBM 622133U, NEC PC-LL550VG3EW, WIPRO WSG48105V-0015, and more.

There is no particular operating system known to have specific problems with Ring 4012pm 150dpi
Laptop Ring 4012pm 150dpiTablet Ring 4012pm 150dpiDownload Ring 4012pm 150dpiUpgrade Ring 4012pm 150dpiUpdate Ring 4012pm 150dpi2017 Ring 4012pm 150dpiFree Ring 4012pm 150dpiData Ring 4012pm 150dpiInfo Ring 4012pm 150dpiHelp Ring 4012pm 150dpiGuide Ring 4012pm 150dpiComments Ring 4012pm 150dpiWindows 10 Ring 4012pm 150dpiVista Ring 4012pm 150dpiWindows 7 Ring 4012pm 150dpiInstall Ring 4012pm 150dpi