Editing IBM RT PC

{{short description|Early RISC workstation from IBM}}
{{more footnotes|date=November 2017}}
{{Infobox information appliance
| name      = IBM RT PC<br />(RISC Technology Personal Computer)
| logo      = IBM logo.svg
| logo_size = 120px
| image     = IBM RT PC at Vintage Computer Festival Soutwest (1).jpg
| caption   = 
| cpu       = [[IBM ROMP]]
| memory    = 1 [[Megabyte|MB]] RAM, expandable to 16 MB
| developer = [[IBM]] / [[IBM Research]]
| manufacturer = [[IBM]]
| type      = [[Workstation computer]]
| releasedate = {{Start date and age|1986}}
| discontinued = May 1991
| os        = [[AIX operating system|AIX]]<br>Academic Operating System<br>[[Pick operating system|Pick]]
| successor = [[IBM RS/6000]]
| related      = [[IBM Personal Computer AT|IBM PC AT]]
}}

The '''IBM RT PC''' ('''RISC Technology Personal Computer''') is a family of [[workstation computer]]s from [[IBM]] introduced in 1986. These were the first commercial computers from IBM that were based on a [[reduced instruction set computer]] (RISC) architecture. The RT PC uses IBM's proprietary [[IBM ROMP|ROMP]] [[microprocessor]], which commercialized technologies pioneered by [[IBM Research]]'s [[IBM 801|801]] experimental minicomputer (the 801 was the first RISC).<ref name="unixreview198603_romp">{{ cite magazine | url=https://archive.org/details/sim_unix-review_1986-03_4_3/page/8/mode/1up | title=The Monthly Report | magazine=UNIX Review | date=March 1986 | access-date=24 June 2022 | last1=Chandler | first1=David | pages=8,10,12,14-16,18,20 }}</ref> The RT PC runs three operating systems: [[AIX operating system|AIX]], the Academic Operating System (AOS), and [[Pick operating system|Pick]].

The RT PC's specifications were regarded as "less than impressive" compared to contemporary workstations by its competitors in that particular market, although the product was deemed deserving of "a healthy amount of respect", particularly with the prospect of IBM as "a serious competitor" who, despite having a product whose performance was an estimated 18 months behind other vendors, would potentially be able to catch up quickly by applying the company's renowned technological capabilities.<ref name="unixreview198603_romp"/> Given such performance limitations, the RT PC had little commercial success as a result. IBM responded by introducing the [[RS/6000]] workstations in 1990, which used a new IBM-proprietary RISC processor, the [[POWER1]]. All RT PC models were discontinued by May 1991.

==Hardware==
Two basic types were produced: a floor-standing desk-side tower (IBM 6150), and a desktop (IBM 6151).<ref name="pcw198701_ibm6150">{{ cite magazine | url=https://www.worldradiohistory.com/UK/Personal-Computer-World/80s/PCW-1987-01-S-OCR.pdf | title=IBM 6150 | magazine=Personal Computer World | date=January 1987 | access-date=3 January 2024 | last1=Jackson | first1=Peter | pages=138-139,142-144 }}</ref> Both types featured a special board slot for the processor card, as well as machine-specific RAM cards. Each machine had one processor slot, one co-processor slot, and two RAM slots.

There were three versions of the processor card: 

* The '''Standard Processor Card''' or ''032 card'' had a 5.88{{nbsp}}[[MHz]] clock rate (170{{nbsp}}ns cycle time), 1{{nbsp}}[[Megabyte|MB]] of standard memory (expandable via 1, 2, or 4{{nbsp}}MB memory boards). It could be accompanied by an optional Floating-Point Accelerator (FPA) board, which contained a 10{{nbsp}}MHz [[National Semiconductor]] [[NS32000|NS32081]] [[floating point]] [[coprocessor]]. This processor card was used in the original RT PC models (010, 020, 025, and A25) announced on January 21, 1986.<ref>{{Cite web|url=https://www.ibm.com/docs/en/announcements/archive/ENUS186-006|title=IBM 6150 RT Personal Computer Models 020, 025, and A25 IBM 6151 RT Personal Computer Model 010|date=21 January 1986}}</ref><ref name=Sanger>{{cite magazine |last=Sager |first=Ira |date=27 January 1986 |title=IBM Retargets Tech Market with RISC-based UNIX System |magazine=[[Electronic News]]}}</ref>

* The '''Advanced Processor Card''' had a 10{{nbsp}}MHz clock (100{{nbsp}}ns) and either 4{{nbsp}}MB memory on the processor card, or external 4{{nbsp}}MB [[Error correction and detection|ECC]] memory cards, and featured a built-in 20{{nbsp}}MHz [[Motorola 68881]] floating-point processor. The Advanced Processor Card could be accompanied by an optional Advanced Floating-Point Accelerator (AFPA) board, which was based around the [[Analog Devices]] ADSP-3220 FP multiplier and ADSP-3221 FP ALU. Models 115, 125, and B25 used these cards. These models were announced on February 17, 1987.<ref>{{Cite web|url=https://www.ibm.com/docs/en/announcements/archive/ENUS187-021|title=IBM RT Personal Computer (RT PC) (TM) New Models and Additional Features|date=17 February 1987}}</ref>

* The '''Enhanced Advanced Processor Card''' sported a 12.5{{nbsp}}MHz clock (80{{nbsp}}ns), 16{{nbsp}}MB on-board memory, while an enhanced advanced floating point accelerator was standard. The models 130, 135, and B35 used these cards. They were announced on July 19, 1988.<ref>{{Cite web|url=https://www.ibm.com/docs/en/announcements/archive/ENUS188-120|title=IBM RT (TM) System New Models|date=19 July 1988}}</ref>

All RT PCs supported up to 16{{nbsp}}MB of memory. Early models were limited to 4{{nbsp}}MB of memory because of the capacity of the DRAM ICs used, later models could have up to 16{{nbsp}}MB. I/O was provided by eight [[ISA bus]] slots. Storage was provided by a 40 or 70{{nbsp}}MB hard drive, upgradeable to 300{{nbsp}}MB. External [[SCSI]] cabinets could be used to provide more storage. Also standard were a mouse and either a 720×512 or 1024×768 pixel-addressable display, and a 4{{nbsp}}Mbit/s [[Token Ring]] network adapter or [[10BASE2]] [[Ethernet]] adapter.

For running [[CADAM]], a [[computer-aided design]] (CAD) program, an IBM 5080 or 5085 graphics processor could be attached. The 5080 and 5085 were contained in a large cabinet that would have been positioned alongside the RT PC. The 5080 was used with a 1,024- by 1,024-pixel IBM 5081 display.<ref>{{cite magazine |last=Derfler, Jr. |first=Frank J. |title=Is There a Workstation in Your Future? |magazine=PC Magazine |volume=5 |issue=11 |date=10 June 1986 |pages=110{{ndash}}113, 115 |url=https://archive.org/details/PC-Mag-1986-06-10/page/n115/mode/2up}}</ref><ref>{{cite book |last1=Peddie |first1=Jon |title=The History of Visual Magic in Computers |date=2013 |publisher=Springer |pages=172{{ndash}}173 |url=https://link.springer.com/book/10.1007/978-1-4471-4932-3 |isbn=978-1-4471-4932-3 |doi=10.1007/978-1-4471-4932-3}}</ref>

===6152 Academic System===
{{Main|IBM Personal System/2#6152 Academic System}}
The 6152 Academic System was a [[IBM PS/2 Model 60|PS/2 Model 60]] with a RISC Adapter Card, a [[Micro Channel]] board containing a ROMP, its support ICs, and up to 8{{nbsp}}MB of memory. It allowed the PS/2 to run ROMP software compiled for the AOS. AOS was downloaded from a RT PC running AOS, via a [[LAN]] [[TCP/IP]] interface.

==Software==
One of the novel aspects of the RT design was the use of a [[microkernel]]. The keyboard, mouse, display, disk drives and network were all controlled by a microkernel, called Virtual Resource Manager (VRM), which allowed multiple operating systems to be booted and run at the same time. One could "hotkey" from one operating system to the next using the Alt-Tab key combination. Each OS in turn would get possession of the keyboard, mouse and display. Both AIX version 2 and the Pick operating system were ported to this microkernel. Pick was unique in being a unified operating system and database, and ran various accounting applications. It was popular with retail merchants, and accounted for about 4,000 units of sales.

The primary operating system for the RT was AIX version 2. Much of the AIX v2 kernel was written in a variant of the [[PL/I]] programming language, which proved troublesome during the migration to AIX v3. AIX v2 included full [[TCP/IP]] networking support, as well as [[Systems Network Architecture|SNA]], and two networking file systems: [[Network File System (protocol)|NFS]], licensed from [[Sun Microsystems]], and IBM [[Distributed Services]] (DS). DS had the distinction of being built on top of SNA, and thereby being fully compatible with DS on the IBM midrange [[AS/400]] and mainframe systems. For the graphical user interfaces, AIX v2 came with the X10R3 and later the X10R4 and X11 releases of the [[X Window System]] from [[MIT]], together with the [[Xaw|Athena widget set]]. [[Compiler]]s for [[C programming language|C]] and [[Fortran]] [[programming language]]s were available.

Some RT PCs were also shipped with the Academic Operating System (AOS), an IBM port of [[Berkeley Software Distribution|4.3BSD]] Unix to the RT PC. It was offered as an alternative to [[IBM AIX|AIX]], the usual RT PC [[operating system]], to US universities eligible for an IBM educational discount. AOS added a few extra features to 4.3BSD, notably [[Network File System (protocol)|NFS]], and an almost [[ANSI C]]-compliant [[C (programming language)|C]] [[compiler]]. A later version of AOS existed that was derived from 4.3BSD-Reno, but it was not widely distributed.

The RT forced an important stepping-stone in the development of the X Window System, when a group at [[Brown University]] ported X version 9 to the system.  Problems with reading unaligned data on the RT forced an incompatible protocol change, leading to version 10 in late 1985.

==Sales and market reception==
When the RT PC was introduced in January 1986, it competed with several workstations from established providers: the [[Apollo Computer]] [[Apollo/Domain|Domain Series 3000]], the [[Digital Equipment Corporation|DEC]] [[MicroVAX|MicroVAX II]], and [[Sun-3|Sun Microsystems Sun-3]].{{r|hamilton19860127}}<ref>{{cite magazine |last=Seymour |first=Jim |title=Marketing the IBM RT PC |date=10 June 1986 |magazine=PC Magazine |page=114}}</ref> Rivals, ''[[Computerworld]]'' said, "breath[ed] a sigh of relief" that IBM's product was neither cheaper nor faster than theirs.<ref name="hamilton19860127">{{Cite magazine |last=Hamilton |first=Rosemary |date=1986-01-27 |title=Workstation vendors claim IBM's RT PC poses no threat |url=https://books.google.com/books?id=33QfOHT69aMC&pg=PA9#v=onepage&q&f=true |access-date=2025-05-29 |magazine=Computerworld |pages=9 |volume=XX |issue=4}}</ref> Analysts said that RT PC was too expensive (almost $40,000 for a [[CAD/CAM]] system) and imitative of rivals' products, with unimpressive graphics and networking capabilities,<ref name="babcock19860127">{{Cite magazine |last=Babcock |first=Charles |date=1986-01-27 |title=IBM unveils RISC system |url=https://books.google.com/books?id=33QfOHT69aMC&pg=PA1#v=onepage&q&f=true |access-date=2025-05-29 |magazine=Computerworld |pages=1,8 |volume=XX |issue=4}}</ref> but expected that IBM would continue to compete for the workstation market.{{r|hamilton19860127}}

The performance of the RT, in comparison with other contemporaneous [[Unix workstations]], was not outstanding. In particular, the [[floating point]] performance was poor,{{cn|date=August 2016}} and was scandalized mid-life with the discovery of a bug in the floating point [[square root]] routine.{{cn|date=August 2016}} [[Personal Computer World]] said "it's hard to see what you get with the 6150 that you can't get by combining any other Unix box to run multi-user applications, with a cheap AT clone to run single-user PC applications".{{r|pcw198701_ibm6150}} Both [[MIT]]'s [[Project Athena]] and [[Brown University]]'s [[Institute for Research in Information and Scholarship]] found the RT inferior to other computers.<ref name="garfinkel19890506">{{cite news | url=https://simson.net/clips/1989/1989.TechRev.Athena.pdf | title=Ripples Across the Academic Market | work=Technology Review | date=May–June 1989 | access-date=25 January 2016 | author=Garfinkel, Simson L. | pages=9–13 | author-link=Simson Garfinkel}}</ref>

Many thought that the RT was part of [[IBM PC|IBM's Personal Computer]] line of computers. This confusion started with its initial name, "IBM RT PC". Initially, it seemed that even IBM thought that it was a high-end Personal Computer given the initially stunning lack of support that it received from IBM. This could be explained by the [[commission (remuneration)|sales commission]] structure the IBM gave the system: salesmen received commissions similar to those for the sale of a PC. With typically configured models priced at $20,000, it was a hard sell, and the lack of any reasonable commission lost the interest of IBM's sales force.{{cn|date=August 2016}}

With the RT system's modest processing power (when first announced), and with announcements later that year by some other workstation vendors, industry analysts questioned IBM's directions. AIX for the RT was another IBM attempt to sell Unix, after [[PC/IX]] for the IBM PC in September 1984. The lack of software packages and IBM's sometimes lackluster support of AIX, in addition to sometimes unusual changes from traditional, de facto UNIX operating system standards, caused most software suppliers to be slow in embracing the RT and AIX. The RT found its home mostly in the [[computer-aided design|CAD]]/[[computer-aided manufacturing|CAM]] and [[CATIA]] markets, with some inroads into the scientific and educational areas, especially after the announcement of AOS and substantial discounts for the educational community. The RT running the Pick OS also found use as shopping store control systems, given the strong database, accounting system and general business support in the Pick OS.  The RT also did well as an interface system between IBM's larger mainframes, due to its SNA and DS support, and some of its point-of-sale terminals, store control systems, and machine shop control systems.

Approximately 23,000 RTs were sold over its lifetime, with some 4,000 going into IBM's development and sales organizations. Pick OS sales accounted for about 4,000 units.

==As part of the NSFNET backbone==
<blockquote>In 1987, "The NSF starts to implement its T1 backbone between the supercomputing centers with 24 RT-PCs in parallel implemented by IBM as ‘parallel routers’. The T1 idea is so successful that proposals for T3 speeds in the backbone begin. [https://www.computerhistory.org/internethistory/1980s Internet History of 1980s]</blockquote>
The [[National Science Foundation Network]] (NSFNET) was the forerunner of the [[Internet]]. From July 1988 to November 1992, the NSFNET's T1 [[Internet backbone|backbone network]] used [[Router (computing)|router]]s built from multiple RT PCs (typically nine) interconnect by a Token Ring LAN.<ref>{{cite journal |last1=Claffy |first1=Kimberly C. |last2=Braun |first2=Hans-Werner |last3=Polyzos |first3=George C. |title=Tracking long-term growth of the NSFNET |journal=Communications of the ACM |date=August 1994 |volume=37 |issue=8 |pages=34–45 |doi=10.1145/179606.179616 |s2cid=3013869 |doi-access=free }}</ref>

==References==
{{Reflist}}

==Further reading==
* {{Cite magazine
|last=Simpson
|first=R.O.
|date=1986
|title=The IBM RT Personal Computer
|magazine=[[Byte (magazine)|Byte]], Extra Edition
|pages=43,76<!--The article is probably longer; the bibliography database listed these page numbers as a range, which is probably too long-->
}}
* {{Cite magazine 
|last1=Hoffman 
|first1=Thomas V. 
|magazine=PC Tech Journal
|title=PC RT: A Significant departure
|date=December 1986 
|publisher=Ziff-Davis }} {{mdash}} Contains 4 significant technical articles about the Machine, processor and architecture. 

*{{cite book 
|last1=Waters 
|first1=Frank
|last2=Henry 
|first2=G Glen
|title=IBM RT Personal Computer Technology 
|date=1986
|publisher=IBM Engineering System Products
}} {{mdash}} IBM Pub SA23-1057-00 

*{{cite book 
|last1=Duntemann
|first1=Jeff 
|last2=Pronk 
|first2=Ron 
|title=Inside the PowerPC Revolution 
|date=1994 
|publisher=Coriolis Group Books}} {{mdash}} Chapter 5 describes the origins of the PowerPC architecture in the IBM 801 and RT PC. [https://technologists.com/sauer/SA23-1057_IBM_RT_Personal_Computer_Technology_1986.pdf]

*{{cite book 
|last1=Ferguson 
|first1=Charles H. 
|last2=Morris 
|first2=Charles R. 
|title=Computer Wars: How the West Can Win in a Post-IBM World 
|date=1993 |publisher=Random House 
|isbn=0812921569}} {{mdash}} Contains an in-depth description of the origins of the RT PC, its development, and subsequent commercial failure.

==External links==
*[http://www.damage.fi/slas/rt/rt.html IBM RT PC-page]
*[https://www.cs.cmu.edu/afs/andrew.cmu.edu/usr/shadow/www/ibmrt.html The IBM RT Information Page]
*[https://web.archive.org/web/20050310000006/http://faqs.jmas.co.jp/FAQs/ibm-rt-faq/ JMA Systems's FAQ Archive]
*[https://www.youtube.com/watch?v=iEou9AbTVT0#t=400 video in operation]
* {{cite magazine |date=27 January 1986 |title=IBM joins 32-bit fray with RT line |url=https://books.google.com/books?id=33QfOHT69aMC&pg=PA8 |magazine=Computerworld |page=8 |issn=0010-4841}}
* {{webarchive |url=https://web.archive.org/web/20070312051027/http://www.uni-giessen.de/faq/archiv/ibm-rt-faq.aos/msg00000.html |date=March 12, 2007 |title=AOS FAQ }}
''This entry incorporates text from the [http://www.damage.fi/slas/rt/faq/ RT/PC FAQ ].''

{{IBM midrange computers}}

[[Category:IBM workstations|RT PC]]
[[Category:Computer-related introductions in 1986]]
[[Category:32-bit computers]]