Editing IBM System/34 (section)

==Hardware==
The 5340 System Unit contained the processing unit, the disk storage and the [[floppy disk|diskette drive]]. It had several access doors on both sides. Inside, were swing-out assemblies where the circuit boards and memory cards were mounted. It weighed {{cvt|700|lb|kg}} and used 220V power.<ref>{{cite news |newspaper=[[The New York Times]]
   |url=https://www.nytimes.com/real-estate/usa/tx/collinsville/homes-for-sale/3533-spring-creek-road/2712-56799761
   |title=3533 Spring Creek Road  |date=March 1, 2019
   |quote=Insulated Shop space, with 220V power.}}</ref> The [[IBM 5250]] series of [[Computer terminals|terminals]] were the primary interface to the System/34.

===Processors===
S/34s had two processors, the Control Storage Processor (CSP), and the Main Storage Processor (MSP). The MSP was the workhorse, based on [[System/3]] architecture; it performed the instructions in the computer programs. The CSP was the governor, a different processor with different [[RISC]]-like instruction set, based on [[System/32]] architecture; it performed system functions in the background. The CSP also executed the optional ''Scientific Macroinstructions'', which were a set of emulated floating point operations used by the System/34 Fortran compiler and optionally in assembly code.<ref>{{cite web|url=http://www.bitsavers.org/pdf/ibm/system34/SA21-9275-0_IBM_System_34_and_System_32_Scientific_Microinstructions_Functions_Reference_Manual_1st_ed_197807.pdf|title=IBM System/34 and IBM System/32 Scientific Macroinstructions Functions Reference Manual|date=July 1978|publisher=IBM|access-date=2021-12-22|website=Bitsavers}}</ref> The clock speed of the CPUs inside a System/34 was fixed at 1&nbsp;MHz for the MSP and 4&nbsp;MHz for the CSP. Special utility programs were able to make direct calls to the CSP to perform certain functions; these are usually system programs like $CNFIG which was used to configure the computer system.
[[File:IBM System34 drives.jpg|left|thumb|Picture of a System/34 showing the diskette magazine drive]]

===Memory and storage===
The smallest S/34 had 48K of RAM and an 8.6 MB hard drive. The largest configured S/34 could support 256K of RAM and 256MB of disk space. S/34 hard drives contained a feature called "the extra cylinder," so that bad spots on the drive were detected and dynamically mapped out to good spots on the extra cylinder. Disk space on the System/34 was organized by [[Block (data storage)|blocks]] of 2560 bytes.

The System/34 supported [[memory paging]], referring to as ''swapping''.<ref>{{cite web|url=http://bitsavers.org/pdf/ibm/system34/SC21-7742-3_System_34_Concepts_and_Design_Guide_Jan82.pdf|title=System/34 Concepts and Design Guide|date=January 1982|access-date=2021-08-01|publisher=IBM}}</ref> The System/34 could either swap out entire programs, or individual segments of a program in order to free up memory for other programs to run.

One of the machine's most distinctive features was an off-line storage mechanism that utilized "{{Visible anchor|magazines}}"—boxes of 8-inch floppies that the machine could [[#Upto23|load and eject]] in a nonsequential fashion.<ref name="S34intro78" /><ref>"the diskette magazine drive can process up to 23 diskettes without manual intervention. -p.11</ref><ref>"three slots for holding individual diskettes and two slots for holding magazines of 10 individual diskettes." -p.20</ref>

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