Editing Macintosh II (section)

== Hardware ==
[[Image:Apple Macintosh II motherboard.jpg|thumb|Macintosh II motherboard]]

=== CPU ===
The Macintosh II is built around the [[Motorola 68020]] processor operating at 16 [[Hertz|MHz]], teamed with a [[Motorola 68881]] [[floating-point unit]]. The machine shipped with a socket for an optional [[Motorola 68851]] [[Memory management unit|MMU]], but an "Apple HMMU Chip" (VLSI VI475 chip) was installed by default and could not implement [[virtual memory]] (instead, it translated 24-bit addresses to 32-bit addresses for the Mac OS, which would not be [[32-bit clean]] until [[System 7]]).<ref name=":1">{{Cite book |url=https://archive.org/details/apple-guide-macintosh-family-hardware/page/n513/mode/2up?view=theater |title=Guide to the Macintosh family hardware |date=1990 |publisher=Addison-Wesley Pub. Co |isbn=978-0-201-52405-5 |editor-last=Apple Computer |edition=2nd |location=Reading, Mass |pages=476-478}}</ref>

=== Memory ===
The standard memory was 1 [[megabyte]], expandable to 8 MB.<ref>{{cite web| url=http://www.krsaborio.net/research/1980s/88/880919_c.htm |title=Apple Announces 68030 Macintosh IIx With High Density Compatible Drive | archive-url=https://archive.today/20120908022711/http://www.krsaborio.net/research/1980s/88/880919_c.htm |archive-date=September 8, 2012 | author1=John Cook |author2=Carol Cochrane |work=Business Wire |date=19 September 1988 |access-date=September 20, 2009}}</ref> The Mac II had eight 30-pin [[SIMM]]s, and memory was installed in groups of four (called "Bank A" and "Bank B").

The Macintosh II does not have a [[Memory management unit|PMMU]] installed by default. Instead, it relies on the [[memory controller]] hardware to map the installed memory into a contiguous [[address space]]. This hardware has the restriction that the address space dedicated to Bank A must be larger than that of Bank B. Though this memory controller was designed to support 16 Megabyte, 30-pin SIMMs in each available slot (for a total of up to 128 MB of RAM), the original Macintosh II ROMs have problems that limit the amount of RAM that can be installed into each slot to just 8 MB SIMMs. Although the later Macintosh IIx ROMs that shipped with the Macintosh II FDHD upgrade fixes this initial problem, these newer ROMs still do not have a 32-bit memory manager and cannot boot into 32-bit address mode, at least, not without software assistance in the form of "MODE32", thus limiting the ''total'' amount of RAM to a mere 8MB.<ref>{{cite web |url=http://db.tidbits.com/series/1193 |title=Series: The 24-bit ROM Blues |author=Adam C. Engst |website=[[Tidbits]] |date=April 22, 1991 |access-date=September 21, 2009 |archive-date=June 8, 2011 |archive-url=https://web.archive.org/web/20110608031913/http://db.tidbits.com/series/1193 |url-status=live }}</ref> [[MODE32]] (originally published by [[Connectix]], and later licensed by Apple) contains a workaround that allows for larger SIMMs to be installed in Bank B if a PMMU is also installed. With this configuration, the Macintosh II boot ROMs will believe that the computer has 8 MB or less of RAM installed. Meanwhile, MODE32 then reprograms the memory controller on the fly to dedicate more address space to Bank A, thus allowing access to the additional memory installed in Bank B. Since this makes the physical address space discontiguous, the PMMU is then used to remap the address space into a contiguous block.<ref name=":1" />

=== Graphics ===
The Macintosh II includes a graphics card that supports a true-color 16.7-million-color palette<ref>{{cite web|url=http://www.old-computers.com/MUSEUM/computer.asp?c=160|title=OLD-COMPUTERS.COM : The Museum|website=www.old-computers.com|access-date=April 11, 2018|archive-date=April 4, 2018|archive-url=https://web.archive.org/web/20180404090326/http://www.old-computers.com/museum/computer.asp?c=160|url-status=live}}</ref> and was available in two configurations: 4-bit and 8-bit. The 4-bit model supports 16 colors on a 640×480 display and 256 colors (8-bit video) on a 512×384 display, which means that [[Video random-access memory|VRAM]] was 256 KB. The 8-bit model supports 256-color video on a 640×480 display, which means that VRAM was 512 KB in size. With an optional RAM upgrade (requiring 120 [[nanosecond|ns]] [[Dual in-line package|DIP]] chips), the 4-bit version supports 640×480 in 8-bit color.<ref>{{cite web|url=http://lowendmac.com/video/maciihires.html|title=Macintosh II High Resolution Video Card|date=June 7, 1989|website=lowendmac.com|access-date=April 11, 2018|archive-date=August 29, 2017|archive-url=https://web.archive.org/web/20170829203340/http://lowendmac.com/video/maciihires.html|url-status=live}}</ref> The video card does not include hardware acceleration of drawing operations.

'''Display''': Apple offered a choice of two displays, a 12" black and white unit, and a more expensive 13" high-resolution color display based on Sony's [[Trinitron]] technology. More than one display could be attached to the computer, and objects could be easily dragged from one screen to the next. Third-party displays quickly became available. The [[Los Angeles Times]] reviewer called the color "spectacular."<ref name=":0">{{cite news|url=https://www.latimes.com/archives/la-xpm-1987-03-02-fi-4154-story.html|title=Apple's Two New Machines Are Dandy|first=Lawrence J.|last= Magid|newspaper= Los Angeles Times|date= March 2, 1987|access-date=June 20, 2019 |url-access=limited |quote=...the color is spectacular. Unlike most color monitors, it also displays very readable text.}}</ref> The [[operating system]] [[user interface]] remained black and white even on color monitors with the exception of the Apple logo, which appeared in rainbow color.

=== Storage ===
A 5.25-inch 40 MB internal [[SCSI]] hard disk was optional, as was a second internal 800 kilobyte 3.5-inch floppy disk drive.<ref name=":1" />

=== Expansion ===
Six [[NuBus]] slots were available for expansion (at least one of which had to be used for a [[graphics card]], as the Mac II had no onboard graphics [[chipset]] and the OS didn't support [[Headless computer|headless]] booting). It is possible to connect as many as six displays to a Macintosh II by filling all of the NuBus slots with graphics cards.  Another option for expansion included the [[Mac286]], which included an [[Intel 80286]] chip and could be used for [[MS-DOS]] compatibility.<ref name=":1" />

The original ROMs in the Macintosh II contained a bug that prevented the system from recognizing more than one megabyte of memory address space on a Nubus card. Every Macintosh II manufactured until approximately November 1987 had this defect. This happened because Slot Manager was not 32-bit clean.<ref name=":2">{{cite magazine |magazine=[[InfoWorld]] |date=26 October 1987 |page=47 |volume = 9 |issue = 43 |title= ROM Upgrade to fix bug in Mac II Bus | first = Laurie | last = Flynn | url=https://books.google.com/books?id=_z4EAAAAMBAJ&pg=PA47}}</ref> Apple offered a well-publicized recall of the faulty ROMs and released a program to test whether a particular Macintosh II had the defect.<ref name=":2" />

=== Accessories ===
The Macintosh II and [[Macintosh SE]] were the first Apple computers since the [[Apple I]] to be sold without a keyboard. Instead the customer was offered a choice of the new ADB [[Macintosh keyboard#Apple (Standard) Keyboard (M0116)|Apple Keyboard]] or the [[Apple Extended Keyboard]] as a separate purchase.<ref name=":0" /> Dealers could bundle a third-party keyboard or attempt to [[upsell]] a customer to the more expensive (and higher-profit) Extended Keyboard.

=== Audio ===
The Macintosh II was the first Macintosh to have the [[Chimes of Death]] accompany the [[Sad Mac]] logo whenever a serious hardware error occurred.<ref>{{Cite web |date=2003-11-30 |title=Macintosh: "Sad Macintosh" Error Code Meaning |url=http://docs.info.apple.com/article.html?artnum=7748 |archive-url=http://web.archive.org/web/20090617213904/http://support.apple.com/kb/TA46376?viewlocale=en_US |archive-date=2009-06-17 |access-date=2024-05-24 |website=Apple}}</ref>

The new extensions featured for the Macintosh II at the time were [[A/ROSE]] and Sound Manager.<ref>{{Cite web |last=Maurer |first=Joseph |title=Inside The Macintosh Coprocessor Platform And A/ROSE |url=https://preserve.mactech.com/articles/develop/issue_04/coprocessor.html |access-date=2024-05-24 |website=MacTech {{!}} The journal of Apple technology.}}</ref><ref>{{Cite web |date=1990-05-23 |title=Sound Manager |url=https://developer.apple.com/library/archive/documentation/mac/pdf/Sound/Sound_Manager.pdf |website=Apple Developer}}</ref>