Editing IBM PS/2 (section)

===Memory===
Later PS/2 models introduced the [[SIMM#72-pin SIMMs|72-pin SIMM]]<ref>{{Cite news|url=https://www.pcworld.com/article/258989/the_ibm_ps_2_25_years_of_pc_history.html|title=The IBM PS/2: 25 Years of PC History|work=PCWorld|access-date=2018-08-28|language=en|archive-date=2018-10-04|archive-url=https://web.archive.org/web/20181004213847/https://www.pcworld.com/article/258989/the_ibm_ps_2_25_years_of_pc_history.html|url-status=live}}</ref> which became the [[de facto]] standard for [[Random-access memory|RAM]] modules by the mid-1990s in mid-to-late [[i486|486]] and nearly all [[Pentium (original)|Pentium]] desktop systems. The 72-pin SIMMs were 32/36 bits wide and replaced the old [[SIMM#30-pin SIMMs|30-pin SIMM]] (8/9-bit) standard. The older SIMMs were much less convenient because they had to be installed in sets of two or four to match the width of the CPU's 16-bit (Intel 80286 and [[i386#The 80386SX variant|80386SX]]) or 32-bit (80386 and [[i486|80486]]) data bus, and would have been extremely inconvenient to use in Pentium systems (which featured a 64-bit memory bus). The 72-pin SIMMs were also made with greater capacities (starting at 1 MB and ultimately reaching 128 MB, instead of 256 KB to 16 MB (and usually no more than 4 MB) for 30-pin) and in a more finely graduated range (powers of 2, instead of powers of 4).

Many PS/2 models also used proprietary IBM SIMMs and could not be fitted with commonly available types. However industry standard SIMMs could be modified to work in PS/2 machines if the SIMM-presence and SIMM-type detection bridges, or associated contacts, were correctly rewired.{{Citation needed|date=November 2021}}