Editing IBM 7090 (section)

===IBM 7094===
{| class="infobox" style="font-size:88%;width:34em;"
|+ IBM 7094 registers
|-
|
{| style="font-size:88%;width:100%;"
|-
|colspan="15" | '''Data registers'''
|-
| style="width:10px; text-align:left"  | S
| style="width:10px; text-align:left"  | Q
| style="width:10px; text-align:left"  | P
| style="width:10px; text-align:left"  | <sup>1</sup>
| style="width:10px; text-align:left"  | <sup>2</sup>
| style="width:10px; text-align:left"  | <sup>3</sup>
| style="width:75px; text-align:center"| ...
| style="width:10px; text-align:left"  | <sup>17</sup>
| style="width:10px; text-align:left"  | <sup>18</sup>
| style="width:10px; text-align:left"  | <sup>19</sup>
| style="width:10px; text-align:left"  | <sup>20</sup>
| style="width:10px; text-align:left"  | <sup>21</sup>
| style="width:40px; text-align:center"| ...
| style="width:10px; text-align:center"| <sup>35</sup>
| style="width:auto; background:white; color:black" | ''(bit position)''
|- style="background:silver;color:black"
| style="text-align:center;" colspan="14"| Accumulator
| style="background:white; color:black" | AC
|- style="background:silver;color:black"
| style="text-align:center;" colspan="1"| S
| style="text-align:center;background:white;" colspan="2" | &nbsp;
| style="text-align:center;" colspan="11"| Multiplier/Quotient
| style="background:white; color:black" | MQ
|-
| style="width:10px; text-align:left"  |  
| style="width:10px; text-align:left"  |  
| style="width:10px; text-align:left"  | <sup>0</sup>
| style="width:10px; text-align:left"  | <sup>1</sup>
| style="width:10px; text-align:left"  | <sup>2</sup>
| style="width:10px; text-align:left"  | <sup>3</sup>
| style="width:75px; text-align:center"| ...
| style="width:10px; text-align:left"  | <sup>17</sup>
| style="width:10px; text-align:left"  | <sup>18</sup>
| style="width:10px; text-align:left"  | <sup>19</sup>
| style="width:10px; text-align:left"  | <sup>20</sup>
| style="width:10px; text-align:left"  | <sup>21</sup>
| style="width:40px; text-align:center"| ...
| style="width:10px; text-align:center"| <sup>35</sup>
| style="width:auto; background:white; color:black" | ''(bit position)''
|- style="background:silver;color:black"
| style="text-align:center;background:white;" colspan="2" | &nbsp;
| style="text-align:center;" colspan="12"| Sense Indicators
| style="background:white; color:black" | SI
|-
|colspan="15" | '''Index registers'''
|-
| style="width:10px; text-align:left"  |  
| style="width:10px; text-align:left"  |  
| style="width:10px; text-align:left"  |  
| style="width:10px; text-align:left"  |  
| style="width:10px; text-align:left"  |  
| style="width:10px; text-align:left"  | <sup>3</sup>
| style="width:75px; text-align:center"| ...
| style="width:10px; text-align:left"  | <sup>17</sup>
| style="width:10px; text-align:left"  |  
| style="width:10px; text-align:left"  | 
| style="width:10px; text-align:left"  |  
| style="width:10px; text-align:left"  |  
| style="width:40px; text-align:center"|  
| style="width:10px; text-align:center"|  
| style="width:auto; background:white; color:black" | ''(bit position)''
|- style="background:silver;color:black"
| style="text-align:center;background:white;" colspan="5" | &nbsp;
| style="text-align:center;" colspan="3"| Index Register 1
| style="text-align:center;background:white;" colspan="6" | &nbsp;
| style="background:white; color:black" | XR1 (XRA)
|- style="background:silver;color:black"
| style="text-align:center;background:white;" colspan="5" | &nbsp;
| style="text-align:center;" colspan="3"| Index Register 2
| style="text-align:center;background:white;" colspan="6" | &nbsp;
| style="background:white; color:black" | XR2 (XRB)
|- style="background:silver;color:black"
| style="text-align:center;background:white;" colspan="5" | &nbsp;
| style="text-align:center;" colspan="3"| Index Register 3
| style="text-align:center;background:white;" colspan="6" | &nbsp;
| style="background:white; color:black" | XR3
|- style="background:silver;color:black"
| style="text-align:center;background:white;" colspan="5" | &nbsp;
| style="text-align:center;" colspan="3"| Index Register 4 
| style="text-align:center;background:white;" colspan="6" | &nbsp;
| style="background:white; color:black" | XR4 (XRC)
|- style="background:silver;color:black"
| style="text-align:center;background:white;" colspan="5" | &nbsp;
| style="text-align:center;" colspan="3"| Index Register 5
| style="text-align:center;background:white;" colspan="6" | &nbsp;
| style="background:white; color:black" | XR5
|- style="background:silver;color:black"
| style="text-align:center;background:white;" colspan="5" | &nbsp;
| style="text-align:center;" colspan="3"| Index Register 6
| style="text-align:center;background:white;" colspan="6" | &nbsp;
| style="background:white; color:black" | XR6
|- style="background:silver;color:black"
| style="text-align:center;background:white;" colspan="5" | &nbsp;
| style="text-align:center;" colspan="3"| Index Register 7
| style="text-align:center;background:white;" colspan="6" | &nbsp;
| style="background:white; color:black" | XR7
|-
|colspan="14" | '''Instruction counter'''
|-
| style="width:10px; text-align:left"  |  
| style="width:10px; text-align:left"  |  
| style="width:10px; text-align:left"  |  
| style="width:10px; text-align:left"  |  
| style="width:10px; text-align:left"  |  
| style="width:10px; text-align:left"  | <sup>3</sup>
| style="width:75px; text-align:center"| ...
| style="width:10px; text-align:left"  | <sup>17</sup>
| style="width:10px; text-align:left"  |  
| style="width:10px; text-align:left"  | 
| style="width:10px; text-align:left"  |  
| style="width:10px; text-align:left"  |  
| style="width:40px; text-align:center"|  
| style="width:10px; text-align:center"|  
| style="width:auto; background:white; color:black" | ''(bit position)''
|- style="background:silver;color:black"
| style="text-align:center;background:white;" colspan="5"| &nbsp;
| style="text-align:center;" colspan="3"| Instruction&nbsp;Counter
| style="text-align:center;background:white;" colspan="6"| &nbsp;
| style="background:white; color:black;"| IC
|}
|}

[[File:IBM 7094 console3.agr.jpg|thumb|IBM 7151-2 Console Control Unit for 7094 showing additional index register displays in a distinctive extra box on top. Note "Multiple Tag Mode" light in the top center.]]
An upgraded version, the '''IBM 7094''', was first installed in September 1962.  It has seven [[index register]]s, instead of three on the earlier machines. The 7151-2 Console Control Unit for the 7094 has a distinctive box on top that displays lights for the four new index registers.<ref>{{Cite web|url=http://www.columbia.edu/acis/history/7094.html|title = The IBM 7094}}</ref> The 7094 introduced double-precision floating point and additional [[Instruction set architecture|instructions]], but largely maintained [[backward compatibility]] with the 7090. 
<!-- If there are incompatibilities, please cite sources. -->
Although the 7094 has four more index registers than the 709 and 7090, at power-on time it is in ''multiple tag mode'',<ref name=IBM7094>{{cite manual|url=http://bitsavers.org/pdf/ibm/7094/A22-6703-4_7094_PoO_Oct66.pdf|title=IBM 7094 Principles of Operation|id=A22-6703-4|date=October 21, 1966|publisher=IBM}}</ref>{{rp|8}} compatible with the 709 and 7090, and requires a '''Leave Multiple Tag Mode'''<ref name=IBM7094/>{{rp|56}} instruction in order to enter ''seven index register mode'' and use all seven index registers. In multiple tag mode, when more than one bit is set in the tag field, the contents of the two or three selected index registers are logically [[Bitwise operation#OR|ORed]], not [[Binary number#Addition|added]], together, before the decrement takes place. In seven index register mode, if the three-bit tag field is not zero, it selects just one of seven index registers, however, the program can return to multiple tag mode with the instruction '''Enter Multiple Tag Mode''',<ref name=IBM7094/>{{rp|55}} restoring 7090 compatibility.

In April 1964, the first '''7094 II''' was installed, which had almost twice as much general speed as the 7094 due to a faster [[Clock signal|clock cycle]], dual memory banks and improved overlap of instruction execution, an early instance of [[Instruction pipelining|pipelined]] design.<ref>{{cite manual|url=http://bitsavers.org/pdf/ibm/7094/A22-6760_7094model2.pdf|title=IBM 7094 Model II Data Processing System|id=A22-6760|publisher=IBM}}</ref>

The IBM 7094 was the first computer to fully sing a song using only synthesizers.{{cn|date=May 2025}}