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IBM System/390
open-in-new
<h2 id="history">History</h2> <p>On September 5, 1990, IBM published a group of hardware and software announcements, two<a class="footnote-ref" id="fnref:1" href="#fn:1"><sup>1</sup></a><a class="footnote-ref" id="fnref:2" href="#fn:2"><sup>2</sup></a> of which included overviews of three announcements: </p> <ul><li>System/390<a class="footnote-ref" id="fnref:3" href="#fn:3"><sup>3</sup></a> (S/390), as in 360 for 1960s, 370 for 1970s.</li> <li>Enterprise System/9000<a class="footnote-ref" id="fnref:4" href="#fn:4"><sup>4</sup></a><a class="footnote-ref" id="fnref:5" href="#fn:5"><sup>5</sup></a> (ES/9000), as in 360 for 1960s, 370 for 1970s.</li> <li>Enterprise Systems Architecture/390<a class="footnote-ref" id="fnref:6" href="#fn:6"><sup>6</sup></a><a class="footnote-ref" id="fnref:7" href="#fn:7"><sup>7</sup></a> (ESA/390) was <a href="/facts/IBM/QszA7nwd">IBM</a>'s last <a href="/facts/31-bit_computing/LABpc4UP">31-bit</a>-address/<a href="/facts/32-bit_computing/TDMVce8s">32-bit</a>-data <a href="/facts/IBM_mainframe/0kPkgADx">mainframe</a> computing design, copied by <a href="/facts/Amdahl_Corporation/oCbmoP1z">Amdahl</a>, <a href="/facts/Hitachi%2c_Ltd./KeK38e82">Hitachi</a>, and <a href="/facts/Fujitsu/6e5gvNSa">Fujitsu</a> among other competitors. It was the successor of ESA/370 and, in turn, was succeeded by the <a href="/facts/64-bit_computing/AgvkQHkM">64-bit</a> <a href="/facts/Z%2fArchitecture/FcKYkGn9">z/Architecture</a> in 2000. Among other things, ESA/390 added fiber optics channels, known as Enterprise Systems Connection (<a href="/facts/ESCON/oYh25l0t">ESCON</a>) channels, to the parallel (<a href="/facts/Bus_and_Tag/gbCB2TyR">Bus and Tag</a>) channels of ESA/370.</li></ul> <p>Despite the fact that IBM mentioned the 9000 family first in some of the day's announcements, it was clear "by the end of the day" that it was "for System/390,"<a class="footnote-ref" id="fnref:8" href="#fn:8"><sup>8</sup></a> although it was a shortened name, <i>S/390</i>, that was placed on some of the actual "boxes" later shipped.<a class="footnote-ref" id="fnref:9" href="#fn:9"><sup>9</sup></a><a class="footnote-ref" id="fnref:10" href="#fn:10"><sup>10</sup></a> </p><p>The ES/9000 include rack-mounted models, free standing air cooled models and water cooled models. The low end models were substantially less expensive than the 3090 or <a href="/facts/IBM_4300/lacwydDs">4381</a> previously needed to run <a href="/facts/MVS%2fESA/VPSmB9ML">MVS/ESA</a>, and could also run <a href="/facts/VM%2fESA/Ymu9SRtX">VM/ESA</a> and <a href="/facts/VSE%2fESA/b6Hnxc2p">VSE/ESA</a>, which IBM announced at the same time. </p><p>IBM periodically added named features to ESA/390 in conjunction with new processors; the ESA/390 Principles of Operation manual identifies them only by name, not by the processors supporting them. </p><p>Machines supporting the architecture were sold under the brand System/390 (S/390) from September 1990. The 9672 implementations of System/390 were the first high-end IBM mainframe architecture implemented first with <a href="/facts/CMOS/NJIWYgBl">CMOS</a> CPU electronics rather than the traditional <a href="/facts/Bipolar_junction_transistor/9BMcGv5Q">bipolar</a> logic. </p><p>The IBM z13 was the last z Systems server to support running an operating system in ESA/390 architecture mode.<a class="footnote-ref" id="fnref:11" href="#fn:11"><sup>11</sup></a> However, all 24-bit and 31-bit problem-state application programs originally written to run on the ESA/390 architecture readily run unaffected by this change. </p> <h2 id="s390-computers">S/390 computers</h2> <h3>ES/9000</h3> <p>Eighteen models<a class="footnote-ref" id="fnref:12" href="#fn:12"><sup>12</sup></a> were announced<a class="footnote-ref" id="fnref:13" href="#fn:13"><sup>13</sup></a> September 5, 1990 for the ES/9000 in three form factors; the water-cooled 9021 to succeed the <a href="/facts/IBM_3090/XQR6eSQK">IBM 3090</a>, and the air-cooled standalone 9121 and rack-mounted 9221 to succeed the <a href="/facts/IBM_4300/lacwydDs">IBM 4381</a> and <a href="/facts/IBM_9370/J42PPhxU">9370</a> respectively. The largest announced model had a 100-fold performance over the smallest model, and the clock frequency ranged from 67-111 MHz (15-9 <a href="/facts/Nanosecond/gARLTp4c">ns</a>) in the 9021 and 67 MHz in the 9121 to 26-33 MHz (38-30 ns) in the 9221. The 9221 models 120, 130 and 150 were initially available only with the "System/370 Base Option"; the "ESA Option" shipped in July 1991. The 9221 processors were made of <a href="/facts/Very_Large_Scale_Integration/l1Wgqr27">VLSI</a> <a href="/facts/CMOS/NJIWYgBl">CMOS</a> chips designed in <a href="/facts/B%25C3%25B6blingen/kvMohFX8">Böblingen</a>, Germany, whence the 9672 line later originated. </p><p>The lower 6 of the 8 water-cooled models (codenamed H0) were immediately available, but used the same processor as the 3090-J, still at the 69 MHz (14.5 ns) maximum frequency and thus with unchanged performance. Those models' main difference from the 3090-J was the optional addition of <a href="/facts/ESCON/oYh25l0t">ESCON</a>, <a href="/facts/IBM_Parallel_Sysplex/lTI1aQ9R">Sysplex</a> and Integrated Cryptographic Feature. Only the models 900 and 820 had an all-new design (codenamed H2),<a class="footnote-ref" id="fnref:14" href="#fn:14"><sup>14</sup></a> featuring private split I+D 128+128 KB L1 caches and a shared 4 MB L2 cache (2 MB per side) with 11-cycle latency, more direct interconnects between the processors, multi-level <a href="/facts/Translation_lookaside_buffer/vvwGkfvD">TLBs</a>, <a href="/facts/Branch_target_predictor/ImoX6k7L">branch target buffer</a> and 111 MHz (9 <a href="/facts/Nanosecond/gARLTp4c">ns</a>) clock frequency. These were the first models with <a href="/facts/Out-of-order_execution/bM0dQM8m">out-of-order execution</a> since the <a href="/facts/IBM_System%2f360_Model_195/mSrspKIg">System/370-195</a> of 1973. However unlike the old <a href="/facts/IBM_System%2f360_Model_91/Yo9gocm4">S/360-91</a>-derived systems, the models 900 and 820 had full out-of-order execution for both integer and floating-point units, with <a href="/facts/Tomasulo%2527s_algorithm/Ro81atJm">precise exception handling</a>, and a fully <a href="/facts/Superscalar_processor/gPxRAb25">superscalar</a> pipeline. Models 820 and 900 shipped to customers in September 1991, a year later than the models with older technology. Later these new technologies were used in models 520, 640, 660, 740 and 860.<a class="footnote-ref" id="fnref:15" href="#fn:15"><sup>15</sup></a><a class="footnote-ref" id="fnref:16" href="#fn:16"><sup>16</sup></a><a class="footnote-ref" id="fnref:17" href="#fn:17"><sup>17</sup></a><a class="footnote-ref" id="fnref:18" href="#fn:18"><sup>18</sup></a><a class="footnote-ref" id="fnref:19" href="#fn:19"><sup>19</sup></a> </p><p>All three lines got additions and upgrades until 1993–1994. In February 1993 an 8-processor 141 MHz (7.1 <a href="/facts/Nanosecond/gARLTp4c">ns</a>) model 982 became available, with models 972, 962, 952, 942, 941, 831, 822, 821 and 711 following in March. These models, codenamed H5, had double the L2 cache and 30% higher per-processor performance than the H2 line, and added a hardware <a href="/facts/Lossless_compression/LS702KsN">data compression</a>.<a class="footnote-ref" id="fnref:20" href="#fn:20"><sup>20</sup></a><a class="footnote-ref" id="fnref:21" href="#fn:21"><sup>21</sup></a> The compression was also included in the new, 50% faster models of the 9121.<a class="footnote-ref" id="fnref:22" href="#fn:22"><sup>22</sup></a> In April 1994, alongside the <a href="/facts/CMOS/NJIWYgBl">CMOS</a>-based new 9672 series and improved 9221 models (with 40% faster cycle time and data compression),<a class="footnote-ref" id="fnref:23" href="#fn:23"><sup>23</sup></a> IBM announced also their ultimate <a href="/facts/Bipolar_junction_transistor/9BMcGv5Q">bipolar</a> model, the 10-processor model 9X2 rated at 468 MIPS,<a class="footnote-ref" id="fnref:24" href="#fn:24"><sup>24</sup></a> to become available in October.<a class="footnote-ref" id="fnref:25" href="#fn:25"><sup>25</sup></a><a class="footnote-ref" id="fnref:26" href="#fn:26"><sup>26</sup></a><a class="footnote-ref" id="fnref:27" href="#fn:27"><sup>27</sup></a> </p> <h4>Models</h4> ES/9000 water-cooled models (9021-###)<a class="footnote-ref" id="fnref:28" href="#fn:28"><sup>28</sup></a><table><tbody><tr><th>Model</th><th>CPUs</th><th>Sides</th><th>Max storage(main + <a href="/facts/Z%2fArchitecture/FcKYkGn9">expanded</a>)</th><th>Max channels(Max <a href="/facts/ESCON/oYh25l0t">ESCON</a>)</th><th>Shipping from</th></tr><tr><th scope="col" colspan="8">H0 (340-based models)<a class="footnote-ref" id="fnref:29" href="#fn:29"><sup>29</sup></a><a class="footnote-ref" id="fnref:30" href="#fn:30"><sup>30</sup></a></th></tr><tr><td>720</td><td>6</td><td rowspan="2">2</td><td rowspan="2">0.5+4 GB</td><td rowspan="2">128 (64)</td><td rowspan="5">September 1990</td></tr><tr><td>620</td><td>4</td></tr><tr><td>580</td><td>3</td><td rowspan="4">1</td><td rowspan="2">0.25+2 GB</td><td rowspan="4">64 (32)</td></tr><tr><td>500</td><td>2</td></tr><tr><td>340</td><td>1</td><td>128+1024 MB</td></tr><tr><td>330</td><td>1</td><td>128+512 MB</td><td>"available by upgrade only"</td></tr><tr><th scope="col" colspan="8">H2 (520-based models)<a class="footnote-ref" id="fnref:31" href="#fn:31"><sup>31</sup></a></th></tr><tr><td>900</td><td>6</td><td rowspan="3">2</td><td rowspan="3">1+8 GB</td><td rowspan="3">256 (256)</td><td>September 1991</td></tr><tr><td>860</td><td>5</td><td>February 1992<a class="footnote-ref" id="fnref:32" href="#fn:32"><sup>32</sup></a></td></tr><tr><td>820</td><td>4</td><td>September 1991</td></tr><tr><td>740</td><td>3</td><td>1</td><td rowspan="3">0.5+4 GB</td><td rowspan="3">128 (128)</td><td rowspan="4">February 1992<a class="footnote-ref" id="fnref:33" href="#fn:33"><sup>33</sup></a></td></tr><tr><td>660</td><td rowspan="2">2</td><td>2</td></tr><tr><td>640</td><td rowspan="2">1</td></tr><tr><td>520</td><td>1</td><td>0.25+2 GB</td><td>64 (64)</td></tr><tr><th scope="col" colspan="8">H5 (711-based models)<a class="footnote-ref" id="fnref:34" href="#fn:34"><sup>34</sup></a></th></tr><tr><td>9X2</td><td>10</td><td rowspan="6">2</td><td rowspan="6">2+8 GB</td><td rowspan="6">256 (256)</td><td>October 1994</td></tr><tr><td>982</td><td>8</td><td>February 1993</td></tr><tr><td>972</td><td>7</td><td rowspan="5">March 1993</td></tr><tr><td>962</td><td>6</td></tr><tr><td>952</td><td>5</td></tr><tr><td>942</td><td>4</td></tr><tr><td>941</td><td>4</td><td>1</td><td rowspan="5">1+4 GB</td><td rowspan="5">128 (128)</td></tr><tr><td>832</td><td>3</td><td>2</td><td>August 1993<a class="footnote-ref" id="fnref:35" href="#fn:35"><sup>35</sup></a></td></tr><tr><td>831</td><td>3</td><td>1</td><td rowspan="4">March 1993</td></tr><tr><td>822</td><td>2</td><td>2</td></tr><tr><td>821</td><td>2</td><td rowspan="2">1</td></tr><tr><td>711</td><td>1</td><td>0.5+2 GB</td><td>64 (64)</td></tr></tbody></table> ES/9000 air-cooled standalone models (9121-###)<a class="footnote-ref" id="fnref:36" href="#fn:36"><sup>36</sup></a><a class="footnote-ref" id="fnref:37" href="#fn:37"><sup>37</sup></a><table><tbody><tr><th>Model</th><th>CPUs</th><th>Sides</th><th>Max storage(main + <a href="/facts/Z%2fArchitecture/FcKYkGn9">expanded</a>)</th><th>Max channels(Max <a href="/facts/ESCON/oYh25l0t">ESCON</a>)</th><th>Shipping from</th></tr><tr><th scope="col" colspan="8">320-based models<a class="footnote-ref" id="fnref:38" href="#fn:38"><sup>38</sup></a><a class="footnote-ref" id="fnref:39" href="#fn:39"><sup>39</sup></a></th></tr><tr><td>610</td><td>4</td><td rowspan="3">2</td><td rowspan="3">512+1536 MB</td><td rowspan="3">96 (88)</td><td rowspan="3">March 1992</td></tr><tr><td>570</td><td>3</td></tr><tr><td>490</td><td rowspan="3">2</td></tr><tr><td>480</td><td rowspan="7">1</td><td rowspan="5">256+768 MB</td><td rowspan="5">48 (44)<a class="footnote-ref" id="fnref:40" href="#fn:40"><sup>40</sup></a></td><td rowspan="2">March 1991</td></tr><tr><td>440</td></tr><tr><td>320</td><td rowspan="5">1</td><td rowspan="2">September 1990</td></tr><tr><td>260</td></tr><tr><td>210</td><td>January 1991</td></tr><tr><td>190</td><td>128+384 MB</td><td>32 (28)<a class="footnote-ref" id="fnref:41" href="#fn:41"><sup>41</sup></a></td><td>March 1991</td></tr><tr><td>180</td><td><a class="footnote-ref" id="fnref:42" href="#fn:42"><sup>42</sup></a></td><td>32 (28)</td><td>April 1992<a class="footnote-ref" id="fnref:43" href="#fn:43"><sup>43</sup></a></td></tr><tr><th scope="col" colspan="8">511-based models<a class="footnote-ref" id="fnref:44" href="#fn:44"><sup>44</sup></a></th></tr><tr><td>742</td><td>4</td><td rowspan="3">2</td><td rowspan="3">1+1 GB<a class="footnote-ref" id="fnref:45" href="#fn:45"><sup>45</sup></a></td><td rowspan="3">128</td><td rowspan="3">May 1993</td></tr><tr><td>732</td><td>3</td></tr><tr><td>622</td><td rowspan="4">2</td></tr><tr><td>621</td><td>1</td><td>0.5+0.5 GB<a class="footnote-ref" id="fnref:46" href="#fn:46"><sup>46</sup></a></td><td>64</td><td>February 1993</td></tr><tr><td>522</td><td>2</td><td>1+1 GB<a class="footnote-ref" id="fnref:47" href="#fn:47"><sup>47</sup></a></td><td></td><td>November 1993<a class="footnote-ref" id="fnref:48" href="#fn:48"><sup>48</sup></a></td></tr><tr><td>521</td><td rowspan="4">1</td><td rowspan="1">0.5+0.5 GB<a class="footnote-ref" id="fnref:49" href="#fn:49"><sup>49</sup></a></td><td></td><td>May 1993</td></tr><tr><td>511</td><td rowspan="3">1</td><td></td><td></td><td>February 1993</td></tr><tr><td>411</td><td></td><td></td><td rowspan="2">May 1993</td></tr><tr><td>311</td><td></td><td></td></tr></tbody></table> ES/9000 air-cooled rack-mounted models (9221-###)<a class="footnote-ref" id="fnref:50" href="#fn:50"><sup>50</sup></a><table><tbody><tr><th>Model</th><th>CPUs</th><th>Max storage(main + <a href="/facts/Z%2fArchitecture/FcKYkGn9">expanded</a>)</th><th>Max channels(Max <a href="/facts/ESCON/oYh25l0t">ESCON</a>)</th><th>Shipping from</th></tr><tr><th scope="col" colspan="8">170-based models<a class="footnote-ref" id="fnref:51" href="#fn:51"><sup>51</sup></a></th></tr><tr><td>200</td><td>2</td><td rowspan="5">256 MB main</td><td rowspan="2">24 (24)</td><td>Q3 1992<a class="footnote-ref" id="fnref:52" href="#fn:52"><sup>52</sup></a></td></tr><tr><td>170</td><td rowspan="4">1</td><td>Q4 1991</td></tr><tr><td>150</td><td rowspan="3">12 (12)</td><td rowspan="3">December 1990<a class="footnote-ref" id="fnref:53" href="#fn:53"><sup>53</sup></a></td></tr><tr><td>130</td></tr><tr><td>120</td></tr><tr><th scope="col" colspan="8">211-based models<a class="footnote-ref" id="fnref:54" href="#fn:54"><sup>54</sup></a></th></tr><tr><td>421</td><td rowspan="2">2</td><td rowspan="5">512 MB<a class="footnote-ref" id="fnref:55" href="#fn:55"><sup>55</sup></a><a class="footnote-ref" id="fnref:56" href="#fn:56"><sup>56</sup></a></td><td>24 (24)</td><td rowspan="5">April 1994</td></tr><tr><td>221</td></tr><tr><td>211</td><td rowspan="4">1</td></tr><tr><td>201</td></tr><tr><td>191</td></tr></tbody></table> <h4>ES/9000 features</h4> <ul><li><a href="/facts/ESCON/oYh25l0t">ESCON</a> fiber optic <a href="/facts/Channel_I%2fO/vDBtN2wQ">channels</a></li> <li><a href="/facts/IBM_Parallel_Sysplex/lTI1aQ9R">Sysplex</a> for synchronizing the systems to ease management</li> <li>Vector Facility: up to one <a href="/facts/Vector_processor/nYAsIKT0">vector processor</a> per Central Processor available on the 9021 and 9121. First used on the 3090 to replace the IBM 3838 array processor announced in 1976 for System/370.<a class="footnote-ref" id="fnref:57" href="#fn:57"><sup>57</sup></a></li> <li>Up to one Integrated Cryptographic Feature (ICRF) per side was available on the 9021 for accelerating <a href="/facts/Encryption/16q29Fdv">encryption</a>, succeeding the 3848 Cryptographic Unit.</li> <li>(Each Central Processor accommodates one <a href="/facts/Coprocessor/WsVXzAGo">coprocessor</a> at a time; the combined number of installed Vector Facilities and ICRFs cannot exceed the number of Central Processors.)</li> <li>The new models of the 9021 and 9121 from 1993 and 9221 from 1994 feature <a href="/facts/Lossless_compression/LS702KsN">data compression</a> hardware.</li></ul> <h4>Logical partitioning</h4> <p class="note">Main article: <a href="/facts/Logical_partition/4JYGqyen">Logical partition</a></p> <p>Previously available only on <a href="/facts/IBM_3090/XQR6eSQK">IBM 3090</a>, Logical Partitions (LPARs) are a standard feature of the ES/9000 processors whereby IBM's <i>Processor Resource/Systems Manager</i> (PR/SM) <a href="/facts/Hypervisor/3gX9fKlH">hypervisor</a> allows different operating systems to run concurrently in separate logical partitions (LPARs), with a high degree of isolation. Initially 7 partitions per a disconnected side were supported.<a class="footnote-ref" id="fnref:58" href="#fn:58"><sup>58</sup></a><a class="footnote-ref" id="fnref:59" href="#fn:59"><sup>59</sup></a> In December 1992 the LPAR capacity of the H2 (520-based) models was increased to 10 per a disconnected side. For example, a two-processor model 660 could now support up to 20 partitions instead of 14, if the two sides (each with one processor) are electrically isolated.<a class="footnote-ref" id="fnref:60" href="#fn:60"><sup>60</sup></a> </p><p>This was introduced as part of IBM's moving towards "lights-out" operation and increased control of multiple system configurations. </p> <h3>9672</h3> <p>Launched in 1994 first as the "Parallel Transaction Server" (alongside the 9673 "Parallel Query Server"),<a class="footnote-ref" id="fnref:61" href="#fn:61"><sup>61</sup></a> subsumed by the "Parallel Enterprise Server" launched later in the year,<a class="footnote-ref" id="fnref:62" href="#fn:62"><sup>62</sup></a> the six generations of the IBM 9672 machines transitioned IBM's mainframes fully to <a href="/facts/CMOS/NJIWYgBl">CMOS</a> microprocessors, as by a strategic decision no more ES/9000 (<a href="/facts/Bipolar_junction_transistor/9BMcGv5Q">bipolar</a>-based except the 9221) models would be released after 1994. The initial generations of 9672 were slower than the largest ES/9000 sold in parallel, but the fifth and sixth generations were the most powerful and capable ESA/390 machines built by IBM.<a class="footnote-ref" id="fnref:63" href="#fn:63"><sup>63</sup></a> </p> <table><tbody><tr><th>Model</th><th>Year Introduced</th><th>Number of CPUs</th><th>Performance (MIPS)<a class="footnote-ref" id="fnref:64" href="#fn:64"><sup>64</sup></a></th><th>Memory (GB)</th></tr><tr><td>G1 – 9672-R<i>n</i>1, 9672-E<i>nn</i>, 9672-P<i>nn</i><a class="footnote-ref" id="fnref:65" href="#fn:65"><sup>65</sup></a></td><td>1994</td><td>1–6</td><td>15–66</td><td>0.125–2</td></tr><tr><td>G2 – 9672-R<i>n</i>2, 9672-R<i>n</i>3</td><td>1995</td><td>1–10</td><td>15–171</td><td>0.125–4</td></tr><tr><td>G3 – 9672-R<i>n</i>4</td><td>1996</td><td>1–10</td><td>33–374</td><td>0.5–8</td></tr><tr><td>G4 – 9672-R<i>n</i>5</td><td>1997</td><td>1–10</td><td>49–447</td><td>0.5–16</td></tr><tr><td>G5 – 9672-<i>nn</i>6</td><td>1998</td><td>1–10</td><td>88–1069</td><td>1–24</td></tr><tr><td>G6 – 9672-<i>nn</i>7</td><td>1999</td><td>1–12</td><td>178–1644</td><td>5–32</td></tr></tbody></table> <p>In the course of the generations, CPUs added more instructions and increased performance. The first three generations (G1 to G3) focused on low cost.<a class="footnote-ref" id="fnref:66" href="#fn:66"><sup>66</sup></a> The 4th generation was aimed at matching the performance of the last <a href="/facts/Bipolar_junction_transistor/9BMcGv5Q">bipolar</a> model, the 9021-9X2. It was decided to be accomplished by pursuing high clock frequencies. The G4 could reach 70% higher frequency than the G3 at silicon process parity, but it suffered a 23% <a href="/facts/Instructions_per_cycle/nHl8f6Ho">IPC</a> reduction from the G3.<a class="footnote-ref" id="fnref:67" href="#fn:67"><sup>67</sup></a> The initial G4-based models became available in June 1997,<a class="footnote-ref" id="fnref:68" href="#fn:68"><sup>68</sup></a> but it wasn't until the 370 MHz model RY5 (with a "Modular Cooling Unit") became available at the end of the year that a 9672 would almost match the 141 MHz model 9X2's performance.<a class="footnote-ref" id="fnref:69" href="#fn:69"><sup>69</sup></a> At 370 MHz it was the second-highest clocked microprocessor at the time, after the <a href="/facts/Alpha_21164/2EE1krYp">Alpha 21164</a> of <a href="/facts/Digital_Equipment_Corporation/ztxs6keA">DEC</a>. The execution units in each G4 processor are duplicated for the purpose of error detection and correction.<a class="footnote-ref" id="fnref:70" href="#fn:70"><sup>70</sup></a> Arriving in late September 1998,<a class="footnote-ref" id="fnref:71" href="#fn:71"><sup>71</sup></a> the G5 more than doubled the performance over any previous IBM mainframe,<a class="footnote-ref" id="fnref:72" href="#fn:72"><sup>72</sup></a><a class="footnote-ref" id="fnref:73" href="#fn:73"><sup>73</sup></a> and restored IBM's performance lead that had been lost to <a href="/facts/Hitachi_Data_Systems/qYvQecjX">Hitachi</a>'s Skyline mainframes in 1995.<a class="footnote-ref" id="fnref:74" href="#fn:74"><sup>74</sup></a><a class="footnote-ref" id="fnref:75" href="#fn:75"><sup>75</sup></a> The G5 operated at up to 500 MHz, again second only to the DEC Alphas into early 1999. The G5 also added support for the <a href="/facts/IEEE_754/dD3e7zAl">IEEE 754</a> floating-point formats.<a class="footnote-ref" id="fnref:76" href="#fn:76"><sup>76</sup></a><a class="footnote-ref" id="fnref:77" href="#fn:77"><sup>77</sup></a> The thousandth G5 system shipped less than 100 days after the manufacturing began; the greatest ramping of production in S/390's history.<a class="footnote-ref" id="fnref:78" href="#fn:78"><sup>78</sup></a> In late May 1999 the G6 arrived featuring <a href="/facts/Copper_interconnects/HBFBVG8X">copper interconnects</a>, raising the frequency to 637 MHz, higher than the fastest DEC machines at the time. </p> <h3>Other</h3> <p>In September 1996 IBM launched the S/390 <a href="/facts/IBM_Multiprise_series/XjzBM9vX">Multiprise</a> 2000, positioned below the 9672.<a class="footnote-ref" id="fnref:79" href="#fn:79"><sup>79</sup></a><a class="footnote-ref" id="fnref:80" href="#fn:80"><sup>80</sup></a><a class="footnote-ref" id="fnref:81" href="#fn:81"><sup>81</sup></a> It used the same technology as the 9672 G3, but it fit half as many processors (up to five) and its off-chip caches were smaller. The 9672 G3 and the Multiprise 2000 were the last versions to support pre-XA <a href="/facts/System%2f370/TRo1jaFw">System/370</a> mode. In October 1997 models of Multiprise 2000 with an 11% higher performance were launched.<a class="footnote-ref" id="fnref:82" href="#fn:82"><sup>82</sup></a> The <a href="/facts/IBM_Multiprise_series/XjzBM9vX">Multiprise 3000</a>, based on the 9672 G5, became available in September 1999, featuring <a href="/facts/Peripheral_Component_Interconnect/n6CGuFvP">PCI</a> buses.<a class="footnote-ref" id="fnref:83" href="#fn:83"><sup>83</sup></a><a class="footnote-ref" id="fnref:84" href="#fn:84"><sup>84</sup></a> </p><p>The <a href="/facts/PC-based_IBM_mainframe-compatible_systems/t1Kx2JAV">S/390 Integrated Server</a>, an even lower-end S/390 system than Multiprise, shipped by the end of 1998. It emerged from a line of S/390-compatibility/coprocessor cards for PCs, but is a true S/390 system capable of server duties, having relegated the Pentium II to the role of an I/O coprocessor. It was the first S/390 server to support PCI. It had the same performance and 256 MB maximum memory capacity as the 7 years older low-end 9221 model 170.<a class="footnote-ref" id="fnref:85" href="#fn:85"><sup>85</sup></a><a class="footnote-ref" id="fnref:86" href="#fn:86"><sup>86</sup></a> </p><p>From 1997 IBM also offered a "S/390 Application StarterPak", intended as a <a href="/facts/Software_development_kit/2Hkk6Hbs">software development kit</a> for developing and testing mainframe software.<a class="footnote-ref" id="fnref:87" href="#fn:87"><sup>87</sup></a> </p> <h2 id="see-also">See also</h2> <ul><li><a href="/facts/IBM_System%2f360/7znvpy4K">IBM System/360</a></li> <li><a href="/facts/IBM_System%2f370/TRo1jaFw">IBM System/370</a></li> <li><a href="/facts/IBM_30XX_mainframe_lines/qUSlntaA">IBM 30XX mainframe lines</a> <ul><li><a href="/facts/IBM_303X/gY2AcmtV">IBM 303X</a></li> <li><a href="/facts/IBM_308X/sxWguzcN">IBM 308X</a></li> <li><a href="/facts/IBM_3090/XQR6eSQK">IBM 3090</a></li></ul></li> <li><a href="/facts/IBM_Z/JJX9eAsD">IBM Z</a></li></ul> <h2 id="notes">Notes</h2> <h2 id="external-links">External links</h2> Wikimedia Commons has media related to IBM System/390. <ul><li>IBM <ul><li><a href="https://www.ibm.com/it-infrastructure/z">IBM Z mainframe homepage</a></li> <li><a href="https://www.ibm.com/it-infrastructure/z/hardware">Current IBM Z mainframe servers</a></li> <li><a href="https://web.archive.org/web/20060126232459/http://www-03.ibm.com/ibm/history/documents/pdf/sys390.pdf">"A Brief History of the IBM ES/9000, System/390 AND zSeries"</a> (PDF). <i>IBM Archives</i>. Archived from <a href="http://www-03.ibm.com/ibm/history/documents/pdf/sys390.pdf">the original</a> (PDF) on January 26, 2006.</li> <li><a href="http://sysrun.haifa.il.ibm.com/ibm/history/exhibits/mainframe/images/2423PH9000.jpg">IBM System/390 Photo</a> <a href="https://web.archive.org/web/20170202061840/http://sysrun.haifa.il.ibm.com/ibm/history/exhibits/mainframe/images/2423PH9000.jpg">Archived</a> 2017-02-02 at the <a href="/facts/Wayback_Machine/nmQ3a6JC">Wayback Machine</a></li></ul></li> <li><a href="http://bitsavers.org/pdf/ibm/390/brochures/GU20-0082_IBM_System_390_Brochure.pdf">"IBM System/390 (brochure)"</a> (PDF). BitSavers. GU20-0082.</li> <li><a href="http://bitsavers.org/pdf/ibm/390/brochures/GU20-0084_The_IBM_Enterprise_System_9000.pdf">"The IBM Enterprise System/9000 (brochure)"</a> (PDF). BitSavers. GU20-0084.</li> <li>Poulsen, Lars. <a href="http://www.beagle-ears.com/lars/engineer/comphist/ibm360.htm">"Generations of the IBM 360/370/3090/390"</a>. <i>Computer History — IBM System/360</i>. Multiple links and references.</li> <li><a href="http://www.computermuseum.org.uk/fixed_pages/IBM_S390.html">"IBM S/390 Generation 5 Parallel Enterprise Server Microprocessor Mainframe"</a>. <i>Jim Austin Computer Collection</i>. UK Computer Museum. Retrieved 2021-04-05. Exterior and interior images of the IBM 390.</li> <li><a href="http://sourceware.org/pub/gcc/summit/2003/Porting%20GCC%20to%20the%20IBM%20S390.pdf">"Porting GCC to the IBM S/390 platform"</a> (PDF). <i>GCC Summit</i>. 2003.</li> <li>Shirriff, Ken (March 2021). <a href="http://www.righto.com/2021/03/logic-chip-teardown-from-vintage-ibm.html">"Teardown of a logic chip from a vintage IBM ES/9000 mainframe"</a>.</li></ul> <h2 id="references">References</h2> <ol> <li id="fn:1"><p>"IBM SYSTEM/390 OVERVIEW: A NEW ERA BEGINS". Announcement Letters. IBM. September 5, 1990. 190-123. Retrieved November 25, 2021. <a href="https://www.ibm.com/common/ssi/ShowDoc.wss?docURL=/common/ssi/rep_ca/3/897/ENUS190-123/index.html" target="_blank">https://www.ibm.com/common/ssi/ShowDoc.wss?docURL=/common/ssi/rep_ca/3/897/ENUS190-123/index.html</a> <a href="#fnref:1" class="footnote-back-ref">↩</a></p></li> <li id="fn:2"><p>"IBM ES/9000 PROCESSOR OVERVIEW". Announcement Letters. IBM. September 5, 1990. 190-124. Retrieved November 25, 2021. <a href="https://www.ibm.com/common/ssi/ShowDoc.wss?docURL=/common/ssi/rep_ca/4/897/ENUS190-124/index.html" target="_blank">https://www.ibm.com/common/ssi/ShowDoc.wss?docURL=/common/ssi/rep_ca/4/897/ENUS190-124/index.html</a> <a href="#fnref:2" class="footnote-back-ref">↩</a></p></li> <li id="fn:3"><p>"System/390 Announcement". IBM Archives. IBM. 23 January 2003. Retrieved 2017-01-29. <a href="https://www.ibm.com/ibm/history/exhibits/mainframe/mainframe_PR390.html" target="_blank">https://www.ibm.com/ibm/history/exhibits/mainframe/mainframe_PR390.html</a> <a href="#fnref:3" class="footnote-back-ref">↩</a></p></li> <li id="fn:4"><p>"ES/9000 Characteristics". IBM Archives. IBM. 23 January 2003. Retrieved 2017-01-29. <a href="https://www.ibm.com/ibm/history/exhibits/mainframe/mainframe_FS9000.html" target="_blank">https://www.ibm.com/ibm/history/exhibits/mainframe/mainframe_FS9000.html</a> <a href="#fnref:4" class="footnote-back-ref">↩</a></p></li> <li id="fn:5"><p>"Enterprise System/9000". IBM Archives. IBM. 23 January 2003. Retrieved 2017-01-29. <a href="https://www.ibm.com/ibm/history/exhibits/mainframe/mainframe_PP9000.html" target="_blank">https://www.ibm.com/ibm/history/exhibits/mainframe/mainframe_PP9000.html</a> <a href="#fnref:5" class="footnote-back-ref">↩</a></p></li> <li id="fn:6"><p>Enterprise Systems Architecture/390 Principles of Operation (PDF) (Ninth ed.). IBM. June 2003. p. 1-1. SA22-7201-08. Retrieved December 8, 2018. <a href="https://publibfp.dhe.ibm.com/epubs/pdf/dz9ar008.pdf" target="_blank">https://publibfp.dhe.ibm.com/epubs/pdf/dz9ar008.pdf</a> <a href="#fnref:6" class="footnote-back-ref">↩</a></p></li> <li id="fn:7"><p>Enterprise Systems Architecture/390 Common I/O-Device Commands, Second Edition, IBM, April 1992, SA22-7204-01 <a href="#fnref:7" class="footnote-back-ref">↩</a></p></li> <li id="fn:8"><p>"ES/9000 Characteristics". IBM Archives. IBM. 23 January 2003. Retrieved 2017-01-29. <a href="https://www.ibm.com/ibm/history/exhibits/mainframe/mainframe_FS9000.html" target="_blank">https://www.ibm.com/ibm/history/exhibits/mainframe/mainframe_FS9000.html</a> <a href="#fnref:8" class="footnote-back-ref">↩</a></p></li> <li id="fn:9"><p>"S/390 Parallel Enterprise Server". IBM. 23 January 2003. <a href="https://www.ibm.com/ibm/history/exhibits/mainframe/mainframe_PP390G4.html" target="_blank">https://www.ibm.com/ibm/history/exhibits/mainframe/mainframe_PP390G4.html</a> <a href="#fnref:9" class="footnote-back-ref">↩</a></p></li> <li id="fn:10"><p>S/390 was also used on earlier and subsequent machines. <a href="#fnref:10" class="footnote-back-ref">↩</a></p></li> <li id="fn:11"><p>Accommodate functions for the z13 server to be discontinued on future servers <a href="https://www.ibm.com/support/knowledgecenter/en/SSLTBW_2.1.0/com.ibm.zos.v2r1.e0zm100/z132012hw1.htm" target="_blank">https://www.ibm.com/support/knowledgecenter/en/SSLTBW_2.1.0/com.ibm.zos.v2r1.e0zm100/z132012hw1.htm</a> <a href="#fnref:11" class="footnote-back-ref">↩</a></p></li> <li id="fn:12"><p>Lower case "M" <a href="#fnref:12" class="footnote-back-ref">↩</a></p></li> <li id="fn:13"><p>"Announcement Letter Number C90-015 dated September 5, 1990". IBM. September 5, 1990. <a href="https://www.ibm.com/common/ssi/cgi-bin/ssialias?appname=skmwww&htmlfid=897%2FENUSC90-015&infotype=AN&mhq=RISC%20Microprocessor%20User%27s%20Manual&mhsrc=ibmsearch_a&subtype=CA" target="_blank">https://www.ibm.com/common/ssi/cgi-bin/ssialias?appname=skmwww&htmlfid=897%2FENUSC90-015&infotype=AN&mhq=RISC%20Microprocessor%20User%27s%20Manual&mhsrc=ibmsearch_a&subtype=CA</a> <a href="#fnref:13" class="footnote-back-ref">↩</a></p></li> <li id="fn:14"><p>Also Summit, a codename first denied[12] and later seemingly mentioned by IBM.[13] <a href="#fnref:14" class="footnote-back-ref">↩</a></p></li> <li id="fn:15"><p>Liptay, John S. (July 1992). "Design of the IBM Enterprise System/9000 high-end processor" (PDF). IBM Journal of Research and Development. 36 (4): 713–731. doi:10.1147/rd.364.0713. Archived from the original (PDF) on January 17, 2005. <a href="https://web.archive.org/web/20050117034801/http://www.research.ibm.com/journal/rd/364/ibmrd3604N.pdf" target="_blank">https://web.archive.org/web/20050117034801/http://www.research.ibm.com/journal/rd/364/ibmrd3604N.pdf</a> <a href="#fnref:15" class="footnote-back-ref">↩</a></p></li> <li id="fn:16"><p>Enterprise System/9000 Models 520, 640, 660, 740, 820, and 900 Functional Characteristics and Configuration Guide (PDF). IBM. September 1991. GA22-7139-02. <a href="http://vtda.org/docs/computing/IBM/Mainframe/Hardware/System/GA22-7139-02_ESystem9000-520-900FunctionalCharConfig_Sep91.pdf" target="_blank">http://vtda.org/docs/computing/IBM/Mainframe/Hardware/System/GA22-7139-02_ESystem9000-520-900FunctionalCharConfig_Sep91.pdf</a> <a href="#fnref:16" class="footnote-back-ref">↩</a></p></li> <li id="fn:17"><p>"ES/9000 Reference guide" (PDF). IBM. GU20-0088. <a href="http://bitsavers.org/pdf/ibm/390/GU20-0088_ES9000_Reference_Guide.pdf" target="_blank">http://bitsavers.org/pdf/ibm/390/GU20-0088_ES9000_Reference_Guide.pdf</a> <a href="#fnref:17" class="footnote-back-ref">↩</a></p></li> <li id="fn:18"><p>Hamilton, Rosemary (September 16, 1991). "IBM turns up pressure to move to ES/9000". Computerworld. Vol. 25, no. 37. p. 131. The high-end Models 820, 860 and 900 use new generation, or Summit, technology and will be generally available this week, said [IBM senior vice president Carl] Conti. <a href="https://archive.org/details/computerworld2537unse/page/131/mode/1up" target="_blank">https://archive.org/details/computerworld2537unse/page/131/mode/1up</a> <a href="#fnref:18" class="footnote-back-ref">↩</a></p></li> <li id="fn:19"><p>"IBM Enterprise System/9000 Introducing a new computing family" (PDF). IBM. The ES/9000 family's 18 models - successors to the proven IBM Enterprise System families ES/9370, ES/4381, and ES/3090 - provide a solid foundation for increased computing performance and function. The family's performance range spans a 100-fold growth from the compact, rack-mounted Model 120 to the powerful Model 900. <a href="http://bitsavers.org/pdf/ibm/390/brochures/GU20-0082_IBM_System_390_Brochure.pdf" target="_blank">http://bitsavers.org/pdf/ibm/390/brochures/GU20-0082_IBM_System_390_Brochure.pdf</a> <a href="#fnref:19" class="footnote-back-ref">↩</a></p></li> <li id="fn:20"><p>"Ten New IBM ES/9000 Water-Cooled Processors, Including Seven-Way and Eight-Way Processors, Associated Upgrades, and Additional Functions". IBM. February 9, 1993. <a href="https://www.ibm.com/common/ssi/cgi-bin/ssialias?appname=skmwww&htmlfid=897%2FENUS193-033&infotype=AN&mhq=sysplex&mhsrc=ibmsearch_a&subtype=CA" target="_blank">https://www.ibm.com/common/ssi/cgi-bin/ssialias?appname=skmwww&htmlfid=897%2FENUS193-033&infotype=AN&mhq=sysplex&mhsrc=ibmsearch_a&subtype=CA</a> <a href="#fnref:20" class="footnote-back-ref">↩</a></p></li> <li id="fn:21"><p>"Processor Capacity Planning: LSPR Workload Sensitivities" (PDF). IBM. 1999. <a href="https://public.dhe.ibm.com/software/mktsupport/techdocs/lsprprz.pdf" target="_blank">https://public.dhe.ibm.com/software/mktsupport/techdocs/lsprprz.pdf</a> <a href="#fnref:21" class="footnote-back-ref">↩</a></p></li> <li id="fn:22"><p>"Announcement Letter Number C93-002 dated February 9, 1993". IBM. February 9, 1993. <a href="https://www.ibm.com/common/ssi/cgi-bin/ssialias?appname=skmwww&htmlfid=897%2FENUSC93-002&infotype=AN&mhq=IBM%20Compiler%20and%20Library%20for%20REXX%20on%20IBM%20Z&mhsrc=ibmsearch_a&subtype=CA" target="_blank">https://www.ibm.com/common/ssi/cgi-bin/ssialias?appname=skmwww&htmlfid=897%2FENUSC93-002&infotype=AN&mhq=IBM%20Compiler%20and%20Library%20for%20REXX%20on%20IBM%20Z&mhsrc=ibmsearch_a&subtype=CA</a> <a href="#fnref:22" class="footnote-back-ref">↩</a></p></li> <li id="fn:23"><p>"IBM INTRODUCES FIVE NEW CMOS-BASED ES/9000s". IBM. April 5, 1994. Archived from the original on 18 October 1996. <a href="https://web.archive.org/web/19961018041819/http://fnctsrv0.chips.ibm.com/news/1994/94040503.html" target="_blank">https://web.archive.org/web/19961018041819/http://fnctsrv0.chips.ibm.com/news/1994/94040503.html</a> <a href="#fnref:23" class="footnote-back-ref">↩</a></p></li> <li id="fn:24"><p>As explained by IBM,[22] the MIPS ratings are varying estimates. Besides 468 MIPS,[23][24][25] ratings of 465,[26][27] 467,[28] 475,[29] 480,[30][31] 484.5,[32] and 485[33] MIPS exist. IBM's own publication also implies 485 MIPS,[34] but later IBM rated it 510 MIPS.[35] For different workloads different ratings exist, calculated from IBM's LSPR ratings, which can change with OS and microcode updates.[27] Hence confusion.[36] The rated MIPS should also not be confused with the theoretical maximum sustainable MIPS, which is 2817 for model 9X2. <a href="#fnref:24" class="footnote-back-ref">↩</a></p></li> <li id="fn:25"><p>"IBM ES/9000 Water-Cooled Processor Enhancements: New Ten-Way Processor, Parallel Sysplex Capability, and Additional Functions". IBM. April 6, 1994. <a href="https://www.ibm.com/common/ssi/cgi-bin/ssialias?appname=skmwww&htmlfid=897%2FENUS194-084&infotype=AN&mhq=sysplex&mhsrc=ibmsearch_a&subtype=CA" target="_blank">https://www.ibm.com/common/ssi/cgi-bin/ssialias?appname=skmwww&htmlfid=897%2FENUS194-084&infotype=AN&mhq=sysplex&mhsrc=ibmsearch_a&subtype=CA</a> <a href="#fnref:25" class="footnote-back-ref">↩</a></p></li> <li id="fn:26"><p>Stedman, Craig (18 April 1994). "IBM's parallel mainframes take center stage". Computerworld. p. 89. <a href="https://books.google.com/books?id=8RxfG8f4hXgC&pg=PA89" target="_blank">https://books.google.com/books?id=8RxfG8f4hXgC&pg=PA89</a> <a href="#fnref:26" class="footnote-back-ref">↩</a></p></li> <li id="fn:27"><p>"Announcement Overview April 6, 1994". IBM. April 6, 1994. <a href="https://www.ibm.com/common/ssi/cgi-bin/ssialias?appname=skmwww&htmlfid=897%2FENUS194-079&infotype=AN&mhq=sysplex&mhsrc=ibmsearch_a&subtype=CA" target="_blank">https://www.ibm.com/common/ssi/cgi-bin/ssialias?appname=skmwww&htmlfid=897%2FENUS194-079&infotype=AN&mhq=sysplex&mhsrc=ibmsearch_a&subtype=CA</a> <a href="#fnref:27" class="footnote-back-ref">↩</a></p></li> <li id="fn:28"><p>"Enterprise System/9000". IBM Archives. IBM. 23 January 2003. Retrieved 2017-01-29. <a href="https://www.ibm.com/ibm/history/exhibits/mainframe/mainframe_PP9000.html" target="_blank">https://www.ibm.com/ibm/history/exhibits/mainframe/mainframe_PP9000.html</a> <a href="#fnref:28" class="footnote-back-ref">↩</a></p></li> <li id="fn:29"><p>"NEW IBM ENTERPRISE SYSTEM/9000 AND ES/3090-9000T WATER-COOLED PROCESSOR MODELS AND ASSOCIATED UPGRADES". IBM. September 5, 1990. <a href="https://www.ibm.com/common/ssi/cgi-bin/ssialias?appname=skmwww&htmlfid=897%2FENUS190-125&infotype=AN&subtype=CA&mhsrc=ibmsearch_a&mhq=%22ibm%20system%209000%22" target="_blank">https://www.ibm.com/common/ssi/cgi-bin/ssialias?appname=skmwww&htmlfid=897%2FENUS190-125&infotype=AN&subtype=CA&mhsrc=ibmsearch_a&mhq=%22ibm%20system%209000%22</a> <a href="#fnref:29" class="footnote-back-ref">↩</a></p></li> <li id="fn:30"><p>"Enterprise System.9000 Models 330, 340, 500, 580, 620 and 720 Functional Characteristics and Configuration Guide" (PDF). IBM. September 1991. GA22-7138-01. <a href="http://vtda.org/docs/computing/IBM/Mainframe/Hardware/System/GA22-7138-02_ESystem9000-330-720FunctionalCharConfig_Sep91.pdf" target="_blank">http://vtda.org/docs/computing/IBM/Mainframe/Hardware/System/GA22-7138-02_ESystem9000-330-720FunctionalCharConfig_Sep91.pdf</a> <a href="#fnref:30" class="footnote-back-ref">↩</a></p></li> <li id="fn:31"><p>Enterprise System/9000 Models 520, 640, 660, 740, 820, and 900 Functional Characteristics and Configuration Guide (PDF). IBM. September 1991. GA22-7139-02. <a href="http://vtda.org/docs/computing/IBM/Mainframe/Hardware/System/GA22-7139-02_ESystem9000-520-900FunctionalCharConfig_Sep91.pdf" target="_blank">http://vtda.org/docs/computing/IBM/Mainframe/Hardware/System/GA22-7139-02_ESystem9000-520-900FunctionalCharConfig_Sep91.pdf</a> <a href="#fnref:31" class="footnote-back-ref">↩</a></p></li> <li id="fn:32"><p>Ambrosio, Johanna (24 February 1992). "IBM users welcome early shipments". Computerworld. p. 61. <a href="https://books.google.com/books?id=3xCDoTnlyocC&pg=PA61" target="_blank">https://books.google.com/books?id=3xCDoTnlyocC&pg=PA61</a> <a href="#fnref:32" class="footnote-back-ref">↩</a></p></li> <li id="fn:33"><p>Ambrosio, Johanna (24 February 1992). "IBM users welcome early shipments". Computerworld. p. 61. <a href="https://books.google.com/books?id=3xCDoTnlyocC&pg=PA61" target="_blank">https://books.google.com/books?id=3xCDoTnlyocC&pg=PA61</a> <a href="#fnref:33" class="footnote-back-ref">↩</a></p></li> <li id="fn:34"><p>"Ten New IBM ES/9000 Water-Cooled Processors, Including Seven-Way and Eight-Way Processors, Associated Upgrades, and Additional Functions". IBM. February 9, 1993. <a href="https://www.ibm.com/common/ssi/cgi-bin/ssialias?appname=skmwww&htmlfid=897%2FENUS193-033&infotype=AN&mhq=sysplex&mhsrc=ibmsearch_a&subtype=CA" target="_blank">https://www.ibm.com/common/ssi/cgi-bin/ssialias?appname=skmwww&htmlfid=897%2FENUS193-033&infotype=AN&mhq=sysplex&mhsrc=ibmsearch_a&subtype=CA</a> <a href="#fnref:34" class="footnote-back-ref">↩</a></p></li> <li id="fn:35"><p>"IBM RELEASE NEW ES/9000". Computer Business Review archive at Tech Monitor. August 10, 1993. <a href="https://techmonitor.ai/technology/ibm_release_new_es9000" target="_blank">https://techmonitor.ai/technology/ibm_release_new_es9000</a> <a href="#fnref:35" class="footnote-back-ref">↩</a></p></li> <li id="fn:36"><p>"Enterprise System/9000". IBM Archives. IBM. 23 January 2003. Retrieved 2017-01-29. <a href="https://www.ibm.com/ibm/history/exhibits/mainframe/mainframe_PP9000.html" target="_blank">https://www.ibm.com/ibm/history/exhibits/mainframe/mainframe_PP9000.html</a> <a href="#fnref:36" class="footnote-back-ref">↩</a></p></li> <li id="fn:37"><p>Curran, B. W.; Walz, M.H. (1991). "IBM Enterprise System/9000 Type 9121 system controller and memory subsystem design". IBM Journal of Research and Development. 35 (3). IBM: 357. doi:10.1147/rd.353.0357. <a href="http://domino.research.ibm.com/tchjr/journalindex.nsf/c469af92ea9eceac85256bd50048567c/cba2661999b0bba285256bfa0067fc86!OpenDocument" target="_blank">http://domino.research.ibm.com/tchjr/journalindex.nsf/c469af92ea9eceac85256bd50048567c/cba2661999b0bba285256bfa0067fc86!OpenDocument</a> <a href="#fnref:37" class="footnote-back-ref">↩</a></p></li> <li id="fn:38"><p>"ES/9000 Reference guide" (PDF). IBM. GU20-0088. <a href="http://bitsavers.org/pdf/ibm/390/GU20-0088_ES9000_Reference_Guide.pdf" target="_blank">http://bitsavers.org/pdf/ibm/390/GU20-0088_ES9000_Reference_Guide.pdf</a> <a href="#fnref:38" class="footnote-back-ref">↩</a></p></li> <li id="fn:39"><p>"IBM ANNOUNCEMENTS". Computer Business Review archive at Tech Monitor. October 9, 1991. Note that the "Mb" here means megabyte, not megabit. <a href="https://techmonitor.ai/technology/ibm_announcements_120" target="_blank">https://techmonitor.ai/technology/ibm_announcements_120</a> <a href="#fnref:39" class="footnote-back-ref">↩</a></p></li> <li id="fn:40"><p>ESCON count was initially up to 36.[16] <a href="#fnref:40" class="footnote-back-ref">↩</a></p></li> <li id="fn:41"><p>ESCON count was initially up to 20.[16] <a href="#fnref:41" class="footnote-back-ref">↩</a></p></li> <li id="fn:42"><p>The combined capacity of the main memory and expanded storage is 512 MB. <a href="#fnref:42" class="footnote-back-ref">↩</a></p></li> <li id="fn:43"><p>"IBM HAS 9121, 9221 AS/400-KILLERS; SUMMITS OUT NOW". Computer Business Review archive at Tech Monitor. February 11, 1992. <a href="https://techmonitor.ai/technology/ibm_has_9121_9221_as400_killers_summits_out_now" target="_blank">https://techmonitor.ai/technology/ibm_has_9121_9221_as400_killers_summits_out_now</a> <a href="#fnref:43" class="footnote-back-ref">↩</a></p></li> <li id="fn:44"><p>Announcement Letter Number C93-002 dated February 9, 1993 <a href="https://www.ibm.com/common/ssi/cgi-bin/ssialias?appname=skmwww&htmlfid=897%2FENUSC93-002&infotype=AN&mhq=IBM%20Compiler%20and%20Library%20for%20REXX%20on%20IBM%20Z&mhsrc=ibmsearch_a&subtype=CA" target="_blank">https://www.ibm.com/common/ssi/cgi-bin/ssialias?appname=skmwww&htmlfid=897%2FENUSC93-002&infotype=AN&mhq=IBM%20Compiler%20and%20Library%20for%20REXX%20on%20IBM%20Z&mhsrc=ibmsearch_a&subtype=CA</a> <a href="#fnref:44" class="footnote-back-ref">↩</a></p></li> <li id="fn:45"><p>Initial capacity. Increase to 1+7 GB was scheduled for March 1994. <a href="#fnref:45" class="footnote-back-ref">↩</a></p></li> <li id="fn:46"><p>Initial capacity. Increase to 0.5+3.5 GB was scheduled for March 1994. <a href="#fnref:46" class="footnote-back-ref">↩</a></p></li> <li id="fn:47"><p>Initial capacity. Increase to 1+7 GB was scheduled for March 1994. <a href="#fnref:47" class="footnote-back-ref">↩</a></p></li> <li id="fn:48"><p>"IBM DOES A BIT OF INFILLING WITH 9121 MODEL 522". Computer Business Review archive at Tech Monitor. 30 November 1993. <a href="https://techmonitor.ai/technology/ibm_does_a_bit_of_infilling_with_9121_model_522" target="_blank">https://techmonitor.ai/technology/ibm_does_a_bit_of_infilling_with_9121_model_522</a> <a href="#fnref:48" class="footnote-back-ref">↩</a></p></li> <li id="fn:49"><p>Initial capacity. Increase to 0.5+3.5 GB was scheduled for March 1994. <a href="#fnref:49" class="footnote-back-ref">↩</a></p></li> <li id="fn:50"><p>"Enterprise System/9000". IBM Archives. IBM. 23 January 2003. Retrieved 2017-01-29. <a href="https://www.ibm.com/ibm/history/exhibits/mainframe/mainframe_PP9000.html" target="_blank">https://www.ibm.com/ibm/history/exhibits/mainframe/mainframe_PP9000.html</a> <a href="#fnref:50" class="footnote-back-ref">↩</a></p></li> <li id="fn:51"><p>"ES/9000 Reference guide" (PDF). IBM. GU20-0088. <a href="http://bitsavers.org/pdf/ibm/390/GU20-0088_ES9000_Reference_Guide.pdf" target="_blank">http://bitsavers.org/pdf/ibm/390/GU20-0088_ES9000_Reference_Guide.pdf</a> <a href="#fnref:51" class="footnote-back-ref">↩</a></p></li> <li id="fn:52"><p>"IBM HAS 9121, 9221 AS/400-KILLERS; SUMMITS OUT NOW". Computer Business Review archive at Tech Monitor. 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