Editing Solid Logic Technology (section)

==Later developments==
The same basic packaging technology (both device and module) was also used for the devices that replaced SLT as IBM gradually transitioned to the use of monolithic integrated circuits:

*Solid Logic Dense (SLD) increased packaging density and circuit performance by mounting the discrete transistors and diodes on top of the substrate and the resistors on the bottom.<ref name=ALD>[http://www.bitsavers.org/pdf/ibm/logic/SY22-2798-2_LogicBlocks_AutomatedLogicDiagrams_SLT,SLD,ASLT,MST_TO_Oct71.pdf Logic Blocks Automated Logic Diagrams SLT, SLD, ASLT, MST] (PDF) 86 pages</ref>{{rp|15}} SLD voltages were the same as SLT.
* Unit Logic Device (ULD) use flat-pack ceramic packages, much smaller than SLT's metal cans. Each package contains a ceramic wafer with up to four silicon dies on top, each die implementing one transistor or two diodes; and thick-film resistors underneath. ULDs were used in the [[Launch Vehicle Digital Computer]] and Launch Vehicle Data Adapter of the [[Saturn V]] rocket.<ref>
Ken Shirriff.
[http://www.righto.com/2020/04/a-circuit-board-from-saturn-v-rocket.html "A circuit board from the Saturn V rocket, reverse-engineered and explained"].
2020.
</ref><ref>
Dr. Wernher von Braun.
[https://books.google.com/books?id=4SUDAAAAMBAJ&pg=PA94 "Tiny Computers Steer Mightiest Rockets"].
Popular Science.
Oct 1965.
p. 94-95; 206-208.
</ref>
*Advanced Solid Logic Technology (ASLT) increased packaging density and circuit performance by stacking two substrates in the same package. ASLT is based on the [[Emitter-follower-coupled-switch]] used with [[Emitter-coupled logic|current-steering logic]].<ref name=ALD/>{{rp|18}} ASLT voltage levels were : > +235 mV is high, < -239 mV is low.<ref name=ALD/>{{rp|16}}
{{anchor|IBM_MST}}<!-- do not remove, will be linked -->
*Monolithic System Technology (MST) increased packaging density and circuit performance by replacing discrete transistors and diodes with one to four monolithic integrated circuits (resistors now external from the package on the module). Each MST chip holds about five circuits and is the approximate equivalent of an SLT card.<ref name=ALD/>{{rp|18}} Circuits used [[NPN transistor]]s. MST was first introduced in January 1968 and provided improved cost/performance for IBM's System/370 product line of the 1970s.<ref>{{cite book
 |url=https://books.google.com/books?id=MFGj_PT_clIC&dq=%22IBM%27s+360+and+Early+370+Systems%22+425&pg=PA425
 |title=IBM's 360 and Early 370 System |last1=Pugh|first1=Emerson W.  |last2=Johnson  |first2=Lyle R. |last3=Palmer  |first3=John H.   
 |year=1991 |page=425 |publisher=MIT Press |isbn=9780262161237 |access-date=August 8, 2022}}</ref>