PC-based IBM mainframe-compatible systems: Difference between revisions

Revision as of 11:29, 30 September 2019

Revision as of 21:42, 31 October 2019

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IBM claimed the XT/370 reached 0.1 [[Instructions per second|MIPS]] (when the data fit in RAM). In 1984, the list price of an XT/370 in its typical configuration was approximately $12,000 so compared favorably with IBM's own mainframes on a $/MIPS basis; for example, an [[IBM 4341]] delivered 1.2 MIPS for $500,000. While it theoretically reduced demand on customers' mainframes by offloading load onto the smaller computer, as customers purchased more XT/370s they likely increased the overall load on the mainframes, increasing IBM's mainframe sales.{{r|killen1984fall}}

Similarly to the mainframe version of [[VM/CMS]], the VM/PC also created the illusion of [[Logical disk|virtual disks]], but on the PC version these were maintained as PC- DOS files, either on floppy or hard disk. For example, the CMS virtual disk belonging to user FRED at device address 101 was stored as the DOS file FRED.101. The CMS IMPORT and EXPORT commands allowed extraction of files from these virtual drives as well as [[ASCII]]/[[EBCDIC]] conversion.<ref>BYTE Guide to the IBM PC, fall 1984, pp. 44-46</ref>

The XT/370 came with an XT-style 83-key keyboard (10 function keys).<ref name="byte1984fall">{{cite news | url=https://archive.org/stream/byte-magazine-1984-09/1984_09_BYTE_09-09_Guide_to_the_IBM_PCs#page/n13/mode/2up | title=IBM Personal Computers At a Glance | work=BYTE | date=Fall 1984 | accessdate=18 March 2016 | pages=10–26}}</ref> Newer revisions of the XT/370 dropped the PC3277-EM in favor of the IBM 3278/79 boards. The XT/370 was among the XT systems that could use a second hard drive mounted in the 5161 expansion chassis.<ref name="pc-service-information-manual">{{cite book|title=Personal Computer Family Service Information Manual|date=January 1989|publisher=IBM|id=SA38-0037-00|url=http://bitsavers.org/pdf/ibm/pc/SA38-0037-00_Personal_Computer_Family_Service_Information_Manual_Jul89.pdf}}</ref>{{rp|6-17}}