Prism (chipset)

The Prism brand is used for wireless networking integrated circuit (commonly called "chips") technology from Conexant for wireless LANs.^[1]^[2] They were formerly^[when?] produced by Intersil Corporation,^[1]^[2] before being sold to GlobespanVirata in 2003,^[2]^[3]^[4] which was later acquired by Conexant in early 2004.^[1]^[2]^[3]

Legacy 802.11b products (Prism 2/2.5/3)

The open-source HostAP driver supports the IEEE 802.11b Prism 2/2.5/3 family of chips.^[5]^[6]

Wireless adaptors which use the Prism chipset are known for compatibility, and are preferred for specialist applications such as packet capture.

No win64 drivers are known to exist.^{[citation needed]}

Intersil firmware

WEP^[7]
WPA (TKIP), after update^[8]
WPA2 (CCMP), after update^{[citation needed]}
Access Point mode^[9]^[6]

Lucent/Agere

WEP^{[citation needed]}
WPA (TKIP in hardware)^{[citation needed]}

802.11b/g products (Prism54, ISL38xx)

The chipset has undergone a major redesign for 802.11g compatibility and cost reduction, and newer "Prism54" chipsets are not compatible with their predecessors.^[2]

Intersil initially provided a Linux driver for the first Prism54 chips which implemented a large part of the 802.11 stack in the firmware. However, further cost reductions caused a new, lighter firmware to be designed and the amount of on-chip memory to shrink, making it impossible to run the older version of the firmware on the latest chips.^{[citation needed]} In the meantime, the PRISM business was sold to Conexant,^[3] which never published or provided information about the newer firmware API that would enable a Linux driver to be written.^[2]

A lack of SoftMAC support in the Prime54 driver resulted in only being able to use FullMAC devices.^[10]^[2] However, a reverse engineering effort eventually made it possible to use the newer Prism54 chipsets under the Linux and BSD operating systems.^[2] This effort deprecated the Prism54 driver in the Linux kernel, and has been replaced by the p54 driver which supports both FullMAC and SoftMAC.^[10]

External links

PRISM solutions at Conexant
GPL drivers and firmware for the ISL38xx-based Prism chipsets (mostly reverse engineered)

References

1 2 3 "Conexant to integrate Intersil 802.11b technology into networking chipsets". EE Times. 9 March 2002. Retrieved 23 March 2026.
1 2 3 4 5 6 7 8 Tourrilhes, Jean (25 July 2007). "The devices, the drivers - 802.11a, 802.11g and 802.11n". HP Inc. Retrieved 23 March 2026 – via GitHub.
1 2 3 "Bluetooth and Wi-Fi wireless protocols: a survey and a comparison". IEEE Wireless Communications. 12 (1): 19. 28 February 2005. doi:10.1109/MWC.2005.1404569. eISSN 1558-0687 – via IEEE Xplore. The Intersil Wi-Fi business was sold to GlobespanVirata, which was then acquired by Conexant.
↑ "Wi-Fi chipmakers of the World unite!". The Register. 11 November 2003. Retrieved 23 March 2026.
↑ Verikoukis, Ch.; Perez-Neira, A. I.; Alonso-Zarate, J.; Skiannis, Ch. (4 December 2009). Experimental Performance Evaluation of a MAC Protocol for Cooperative ARQ Scenarios. GLOBECOM 2009 - 2009 IEEE Global Telecommunications Conference (published 4 March 2010). p. 1. doi:10.1109/GLOCOM.2009.5425476. hdl:2117/9030. ISBN 978-1-4244-4148-8. ISSN 1930-529X. Retrieved 23 March 2026 – via IEEE Xplore. HostAP is a Linux based driver for 802.11b WLAN cards based on Intersil's Prism 2.5.
1 2 Bangolae, Sangeetha; Bell, Carol; Qi, Emily (3 July 2006). Performance study of fast BSS transition using IEEE 802.11r. IWCMC06: 2006 International Wireless Communications and Mobile Computing Conference. Vancouver, British Colombia, Canada: Association for Computing Machinery. p. 741. doi:10.1145/1143549.1143696. ISBN 978-1-59593-306-5. Retrieved 23 March 2026. The AP implementation is based on version 0.4.1 of hostapd and the hostap driver for WLAN cards based on the Intersil Prism 2/2.5/3 chipset.
↑ Specifications of PCMCIA Type II 802.11b card: 802C12 (PDF) (Report) (2A ed.). Actiontec. 9 August 2001. pp. 2–3. Retrieved 23 March 2026 – via FCC.
↑ Smith, Tony (30 Apr 2003). "Wi-Fi Alliance drives improved WLAN security". The Register. Retrieved 23 March 2026.
↑ "Kernel Interfaces Manual: wi(4)". FreeBSD Manual Pages (FreeBSD 4.7 ed.). The FreeBSD Project. 2 May 2002. Retrieved 23 March 2026. Cards based on the Intersil PRISM-II and PRISM-2.5 chips also have a host-based access point mode which allows the card to act as an access point (base station). Access points are different than operating in IBSS mode. They operate in BSS mode.
1 2 "p54". Linux Wireless Documentation. kernel.org. Retrieved 23 March 2026.

[:0-1] 1 2 3 "Conexant to integrate Intersil 802.11b technology into networking chipsets". EE Times. 9 March 2002. Retrieved 23 March 2026.

[:1-2] 1 2 3 4 5 6 7 8 Tourrilhes, Jean (25 July 2007). "The devices, the drivers - 802.11a, 802.11g and 802.11n". HP Inc. Retrieved 23 March 2026 – via GitHub.

[:2-3] 1 2 3 "Bluetooth and Wi-Fi wireless protocols: a survey and a comparison". IEEE Wireless Communications. 12 (1): 19. 28 February 2005. doi:10.1109/MWC.2005.1404569. eISSN 1558-0687 – via IEEE Xplore. The Intersil Wi-Fi business was sold to GlobespanVirata, which was then acquired by Conexant.

[4] "Wi-Fi chipmakers of the World unite!". The Register. 11 November 2003. Retrieved 23 March 2026.

[5] Verikoukis, Ch.; Perez-Neira, A. I.; Alonso-Zarate, J.; Skiannis, Ch. (4 December 2009). Experimental Performance Evaluation of a MAC Protocol for Cooperative ARQ Scenarios. GLOBECOM 2009 - 2009 IEEE Global Telecommunications Conference (published 4 March 2010). p. 1. doi:10.1109/GLOCOM.2009.5425476. hdl:2117/9030. ISBN 978-1-4244-4148-8. ISSN 1930-529X. Retrieved 23 March 2026 – via IEEE Xplore. HostAP is a Linux based driver for 802.11b WLAN cards based on Intersil's Prism 2.5.

[:3-6] 1 2 Bangolae, Sangeetha; Bell, Carol; Qi, Emily (3 July 2006). Performance study of fast BSS transition using IEEE 802.11r. IWCMC06: 2006 International Wireless Communications and Mobile Computing Conference. Vancouver, British Colombia, Canada: Association for Computing Machinery. p. 741. doi:10.1145/1143549.1143696. ISBN 978-1-59593-306-5. Retrieved 23 March 2026. The AP implementation is based on version 0.4.1 of hostapd and the hostap driver for WLAN cards based on the Intersil Prism 2/2.5/3 chipset.

[7] Specifications of PCMCIA Type II 802.11b card: 802C12 (PDF) (Report) (2A ed.). Actiontec. 9 August 2001. pp. 2–3. Retrieved 23 March 2026 – via FCC.

[8] Smith, Tony (30 Apr 2003). "Wi-Fi Alliance drives improved WLAN security". The Register. Retrieved 23 March 2026.

[9] "Kernel Interfaces Manual: wi(4)". FreeBSD Manual Pages (FreeBSD 4.7 ed.). The FreeBSD Project. 2 May 2002. Retrieved 23 March 2026. Cards based on the Intersil PRISM-II and PRISM-2.5 chips also have a host-based access point mode which allows the card to act as an access point (base station). Access points are different than operating in IBSS mode. They operate in BSS mode.

[:4-10] 1 2 "p54". Linux Wireless Documentation. kernel.org. Retrieved 23 March 2026.

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