GC20-1754-2 File No. $370-0]

PMBCIUI(o(-micom tal- Mi =9)') Systems System/370 Model 158

Systems

GC20-1754-2 File No. $370-01

A Guide to the IBM System/370 Model 158

This guide presents hardware, programming systems, and other pertinent information about the IBM System/370 Model 158 that describes its significant new features and advantages. Knowledge of the IBM System/370 Model

155 is assumed. Features common to Models 155 and

158 are indicated but not discussed in detail. The contents of the guide are intended to acquaint the reader with the Model 158 and to be of benefit in planning for its instal- lation.

Associated with this guide are four optional supplements that describe operating systems for the Model 158 that support a virtual storage environment. Each supplement has its own form number and must be ordered individually, if required. Optional supplements are the following:

® DOS/Virtual Storage Features Supplement (GC20-1756)

OS/Virtual Storage I Features Supplement (GC20-1752)

® OS/Virtual Storage 2 Features Supplement (GC201753)

@ Virtual Machine Facility/370 Features Supplement (GC20-1757)

SIME

Third Edition (August 1975)

This is a major revision obsoleting GC20-1754-1. Text has been added to include information about the Model 3 system (3158-3 Processor Unit), 3056 Remote System Console, Remote Support Facility (RSF), and 3340 direct access storage facility. The 3330 section, virtual machine concepts section and all summary tables have also been updated. Miscellaneous changes have been made throughout the text. Changes to the text and illustrations are indicated by a vertical line in the left margin.

This guide is intended for planning purposes only. It will be updated from time to time; however, the reader should remember that the authoritative sources of system information are the system library publications for the Model 158, its associated components and its programming support. These publications will first reflect any changes.

Requests for copies of IBM publications should be made to your IBM representative or to the IBM branch office serving your locality.

A form has been provided at the back of this publication for readers’ comments. If this form has been removed, address comments to: IBM Corporation, Technical Publications/Systems, Dept. 824, 1133 Westchester Avenue, White Plains, New York 10604. Comments become the property of IBM.

© Copyright International Business Machines Corporation 1972, 1974, 1975

eee”

PREFACE

It is assumed that the reader of this publication is familiar with System/370 Model 155 hardware features, ,channels, I/O devices, and programming Support as described in A Guide to the IBM System/370 Model 155. (GC20-1729), and/or system library publications concerning Model 155 hardware and programming systems support. This guide discusses in detail only the hardware features of the Model 158 that are different from those of the Model 155 and the programming support provided for new features of the Model 158.

There are two versions of the Model 158; the Model 1 and the Model 3. The hardware differences between Model 1 of the Model 158 and the Model 155 are discussed in Sections 01 to 50. The differences between Models 3 and 1 of the Model 158 are discussed in Section 65.

The Model 158 is not compared with a Model 155 II, which is a purchased Model 155 with the optional Dynamic Address Translation Facility installed. However, functional descriptions of Model 158 features that are also part of the Dynamic Address Translation Facility Of the Model 155 II apply to the Model 155 II as well, unless otherwise noted. This publication applies to systems with 60-cycle power.

The total Model 158 guide consists of this base publication (Sections 01 to 70), which covers virtual storage and virtual machine concepts and Model 158 hardware and I/O devices, and from one to four optional supplements (Sections 80 to 110). The optional supplements describe the facilities of the IBM programming systems that support a virtual storage environment using the dynamic address translation hardware of the Model 158. Each optional supplement has its own unigue form number and each supplement desired must be ordered separately and inserted in this base publication, which is distributed without the automatic inclusion of any optional supplements.

The following optional supplements can be inserted in this base publication:

e DOS/Virtual Storage Features Supplement (GC20-1756) - assumes knowledge of DOS Version 4

e OS/Virtual Storage 1 Features Supplement (GC20-1752) - assumes knowledge of OS MFT

e OS/Virtual Storage 2 Release 1 Features Supplement (GC20-1753) - assumes knowledge of OS MVT

e Virtual Machine Facility/370 Features Supplement (GC20-1757) - does not assume knowledge of CP~67/CMS

All optional supplements also assume knowledge of virtual storage, dynamic address translation, and other new Model 158 features as described in this base publication or appropriate system library Manuals. However, no optional supplement requires knowledge of the contents of any other optional supplement.

This base publication, as well as each optional supplement, begins with page 1 and includes its own table of contents and index. The base publication or supplement title is printed at the bottom of each page as a means of identification.

A Guide to the IBM System/370 Model 158

The optional programming systems supplements contain System/370 model-independent information, unless otherwise noted, and are designed to be included in the guides for System/370 Models 135, 145, 158, and 168, as shown below.

Supplements

OS/VS2 DOS/VS OS/VS1 Release 1 VM/370 Features Features Features Features Base Supplement Supplement Supplement Supplement Publications (GC20-1756) (GC20-1752) | (GC20-1753) (GC20-1757)

A Guide to the IBM System/370 Model 135 (GC20-1738-4 or later editions)

A Guide to the IBM System/370 Model 145 (GC20-1734-2 or later editions)

A Guide to the IBM System/370 Model 158 (GC20-1754)

A Guide to the IBM System/370 Model 168 (GC20-1755)

A Guide to the IBM System/370 Model 158

A Guide to the IBM System/370 Model 158

Page of GC20-1754-2 Revised February 20, 1976

By TNL GN20-3580 CONTENTS Base Publication Sections (Sections 01 to 70) Section 01: System Highlights of Models 1 and 3.......... 1 Section 10: Physical Design and System Technology for Models BGAN. 3S) ve: ey ie Se ee a le le Se we ee Re 6 Section 20: Architecture Design and System Components of the MOGGL "2. 2: 5557S, ee Wh Se Se SS SE cts Se, ow Ss Sh Sw Ge 9 20:05 Architecture Design... ee ee ee ee eee ee 9 20:10 The Central Processing Unit ee. der tee ein ee et te ee we we ee Extended Control Mode . ... +. «2 « «© «© «© «© «© © © © © @ 12 New Instructions. .... ie aes Aa a Oe, SS St aw SE i. ee oa a, Se te 2S Improved Instruction Fxecution Speed. .< . « # « « « « « « 18 Clock Comparator and CPU Timer. ... «ie os « © » « AI Reliability, Availability, and Serv iceability Features. . 20 20205. StOrage-< 4. ts. ce ele wt, a Se Se Gr Se ew) <2 os, Ae, Se ee SW eS ee OZ Processor (Main) Storage. . . . 2. « « «© « «© « « «© « « «© «© 23 High-Speed Buffer Storage . . . . 2. 2. « «© «© © © © © © «@ @©)= 26 Reloadable Control Storage. . . .. 2. « « « « « «© «© « «© « = 25 Storage: Control Units is: se ete es We cee es ee eee ee Ga we: CCT 20520. Channels. © <2) “ew: a S & “e, Bie: Sd. we Wa ce Se Rw Oe OF 20:25 System Consoles . « « « s « © © © 4 < « « @ © «© «© « « « » «= 28 Standard Display Console. . .. .. 2. « « « « «© «© « « «© «= 28 The 3056 Remote System Console. . . . 2. 2 2 « «© © © « « « 3261 20:30 Remote Support Facility . . . . . 2. 2. « « « « «© © «© «© «© «© e033 Function and Components . . .. .. 6 « «© «© «© «© «© «© «© « «©0606 33 The Service Processor . . « « « «© « « «e © «© «© «© e «© e «= 35 RETAIN/370 System... la. det: Wein ese GRY ca wt “a Ss, SS we «SS Remote Support Capabilities fe et Se we ee eS oe as ce. SG 20:35 Standard and Optional System Features Sw a SS Se. Sa ee SS Standard Features . . 2. . « 2. « « « «© « «© © © «© © «© © @ e)0= 38 Opti10Onal Peatures. « <i> Sos se SS ww we ew KR Rw ee «=D Section 30: Virtual Storage and Dynamic Address Translation .... 40 30:05 Virtual Storage Concepts, Advantages, and Terminology ... 40 The Need for Larger Address Space . ........ - 40 Virtual Storage and Dynamic Address Translation Concepts. 4h General Advantages Offered by IBM Operating Systems that Support a Virtual Storage Environment ..........- 50 Virtual Storage and Dynamic Address Translation Terminology ... . - : e. 2a -% eo % oe iOF 30:10 Dynamic Address Translation Hardware for Models 1 and 3 Of the Model 158. . . 2. « «© «© «© « «© © © © © @ ee 0 ew ew ew ew) 662 Virtual Storage Organization. . . 2. 2 2 2. 2 « « «© « «© «= 62 Operation of Dynamic Address Translation Hardware .... 63 Features to Support Demand Paging . . . . ......-e- 72 Channel Indirect Data Addressing. . . .- « « « «© « « « « 7&4 30:15 System Performance in a Virtual Storage Environment .... 76 System Resources Required to Support a Virtual Storage ENViTONMENE. 6. s6 6. Sek 0 ces aw Re a Se ee ee ee a ee we we ee OT New Factors that Affect System Performance. .. . S:.e, we “FY Relationship Between Virtual Storage Size and System Performance . . « 2 « « « « «© e « « « * ow Se eae BS Increasing System Performance in a Virtual Storage ENV 1 TORMONE: <6 cass ee Ss eee DW, ew we a we ae es eo ae a ee OT

Page of GC20-1754-2 Revised February 20, 1976

By TNL GN20-3580 Section 40: Virtual Machines. . . . 2. 2. 2. 2 2 6 © © «© © eo ee ew 40:05 Definition and General Operation. . ...... 26 6 « « 40:10 Generali Advantages of a Virtual Machine Environment ... Section 50: I/O Devices for Models 1 and 3. ......424e2e. 50:05 1/0 Device Support. .... 3 ec8 50:10 3333 Disk Storage and Control Model 11 and 3330 Disk Storage Model 11. .... an ro a io fa a oe at ne Attachment via Integrated Storage Controls. Stee ey te SES Ss 90:15 The 3340 Direct Access Storage Facility ... aS Mec us 3340 Disk Storage Drives and the 3348 Data Module ae ae Attachment via 3830 Storage Control Model 2...... Attachment via Integrated Storage Controls. ..... . Intermixing 3340 and 3330-Series Strings on an ACEACHMOENE. 6s ca: 6. Bi ete) Ge me Ss. HSL em. SS ee oe ce ce ee OR OUMMALY jo: 2) 6 @ SB le we ee aw) Se we ee Section

Section 70: 05

70:10 70:15

Performance Facilities. .... Other Differences ....... ; MULELDYOCESSING: «. 2. «6%, © 6) @ we SS me we Se ee Programming Systems Support .... .... «2. 2. «6 «

65: Differences Between the Model 3 and the Model1i..

e 6 6 e 6 e e e e 6 e a e e

70: Comparison Tables .... So Nee Ge: «oat Tae er te es OO BS eS Comparison Table of Hardware Features for SystenV 360 Models 50 and 65 and System/370 Models 145, 155, 155 II,

and 158 (Models 1 and 3)... . DOS and DOS/VS Support of the Model 158 (Models 1 and 3). OS and OS/VS Support of the Model 158 (Models 1 and 3). .

Index (Sections O01 to 70). . ...-. « « « «© «© © © 6 0 oe ew ew tw

Optional Sections (See each supplement fcr detailed contents and

Section Section Section

Section

FIGURES

10.1 10.2 20.10.1 20.10.2

20.10. 3

20.10. 4 20.15.71 20.25.1 20.30.12 30.05.1

30.05.2

index) 80: DOS/Virtual Storage Features. ..... .....e.s. 90: OS/Virtual Storage 1 Features ........-e.e... 100: OS/Virtual Storage 2 Release 1 Features. ......

110: Virtual Machine Facility/370 Features. ......

(Sections 01 to 70)

System/370 Model 158 (design model) .......-... SLT substrate ... gS. os re a Ses: WE, 3S. Stee, es He RL ae oe BC mode and EC mode PSW formats oh te: fen St ws Ss SS ae Se Model 158 model-independent fixed storage locations for

BC and EC modes ... be os ale es ta at. se Bo Wahi Yee. ver Se Ya oe Model 158 (Model 1) mode 1-dependent fixed storage locations .. By Ws hee SP. te, eo are ee! os

Model 158 machi ne check code. a 2G seh Map. Sige, High-speed buffer organization in the Model Model 158 display console ........ . Components of the Remote Support Facility . Names and location of instructions and data ina virtual storage environment . . . 2. 2. « « « « « © « © « © « « Relationship of virtual storage, direct access storage, and real Storage... <: 6.6: <e..e- ew ee eS lS ORR

e oe « e e e e

se 6 feo

92 $2 100

103 103

103 104 108 108 123 126

128 129

134 134 136

139 139

140

141 154 160

167

173 175 177

179

Wd J

15

16 22 25 29 34

46

uy

A Guide to the IBM System/370 Model 158

30.05.3 30.05. 4

30.10.1 30.10. 2

30.10.3 30.10.48 30.10.5

30.15.1

30.15.2

30.15. 3 30.15.4 30.15.5 40.05.1 40.05.2 40.05.3 50.10.1 50.10. 2 50.15.1

50.15. 2 50.15.3

50.15.4 50.15.5 50.15.6 50.15.7 50.15.8 50.15. 9

50.15.10

65.1

A Guide to the IBM System/370 Model 158

Page of GC20-1754-2

Revised February 20, 1976

By TNL GN20-3580

Conceptual illustration of real storage utilization in a mixed batch and online virtual storage environment. . . Layout of virtual storage, external page storage, and real storage. ..... a ee ek SP es eG Ser Virtual storage address fields for. a 64K segment. . .. . Segment table and page tables used for dynamic address translation ....«.«.s «© « « es teh he as ie Sh ie cD Gm, “Gt 2s Dynamic address translation procedu re Be ae. ee es We. ee wet ey lee TLB purging when control register 1 is changed. ..... Example of IDAL‘'s required for a CCW list when page size BS 2 ey ee See Me, SS SS, SE a Se OS se es a ee “ee: he Possible system performance when a virtual storage operating system is used with a Model 158 with the same I/O configuration and real rene size as the replaced Model 155. ....... a Se ers. tah, ea? et oe: 2. General effect on page faults of increasing the ratio of virtual storage used to real storage present in the SYS COM s. a: e-. Ger. Ne Si. Hae es, tee Sg 1S ee, Lae * © © © © «© © « General effect on system performance of the paging Tacror OnLy ~ 2. ee. “sss wee eh GR. SE Ss “Sei Se me ee ta ee ee General effect of the paging factor on system performance for various active-to-passive page ratios ........ General system performance curve for a virtual storage environment .. a ee eee ee ee ee ee ee ee Conceptual illustration of the real and virtual machine environment that is supported by VM/370 ...... - i Conceptual illustration of the implementation of virtual storage in a virtual machine environment. . ....... Segment table and page tables built when a virtual storage Operating system executes in a virtual machine. . Permissible 3330-series string configurations for the Model 158 integrated storage controls feature ...... Sample 3330-series eau: enemas with ree Switching... ee A five-drive 3340 string “with 3340. Model A2, “B2, “and a MINES. ag: des St fe ie RP eS ey Sa ee Sk Sf hs sk ee See. SG The 3348 Data Module. .... * SiS: tas ee Ue ee Location of physical and logical tracks and read/write heads on a data surface in a 3348 Data Module ... Cylinder and read/write head layout for a 3348 Model. 35 Data Module . . 2. «© « « « «© « © «© © « « «@ Cylinder and read/write head layout for a 3348 Model 70 a

Da ta Mod ule 6 e@ e * @ e « e e e e ® e e Cylinder and read/write head layout for

3348 Model 70F.

Data Module ...... 7 Mn Bet A. SL He el ee A Model 158 configuration with 3340 disk pee ede attached via 3830 Storage Control Model 2... ° ° String ice anagsice for 3340 facilities attached to a "3830 Model 2... ‘38 .

Permissable 3340 “string configurations for the Model 158 Integrated Storage Controls feature ..... * oer «8

String switching for 3340 facilities attached to one Isc e e@ e e e e e e e e e e e e e @ e e @ e e e e e e

High-speed buffer organization in the Model 3 ..... .

56

59 64

66 67 70

75

80

84 85 85 87 94 96 97 106 107

109 109

113 115 116 118 123 125 127

129 135

Page of GC20-1754-2 Revised February 20, 1976 By TNL GN20-3580

TABLES (Sections 01 to 70)

20.15.1 20.25.1

30.10.1 30.10.2 50.10.1

50.10.2 50.15.1

50.155.2 50.15.3

50.15.4

Model 158 Model 1 cycle and access times. . ......e. 23 Functional capabilities of the standard display console

and the 3056 Remote System Console. . ... .... .-.-s 33 Number and size of segments and pages for a 16-million-

byte virtual storage. ........«... . a a - 63 Virtual and real storage addresses used by and suppl ied

to programs in the Model 158. . .......2.2.2.6.06.08. i721 Capacity and ea characteristics for 3330-series

drives. . wm: eee Te i ss Sy sie pe’ fon et OM 3336 Model 1 “and “44 Disk Pack characteristics cw eS we we 108 Physical and capacity characteristics of 3348 Data

Modules and the 2316 Disk Pack. ... a Hee ie ast ee le. tee te es, DEO Timing characteristics of the 3340 direct access ecu as

facility and the 2314 facility. ... . a on =, £21 Summary of the hardware features of 3340 and 2314 disk storage facilities. .. - P ei Se es SY Hes. Jal ee OL

Summary of the features of 3830 Storage Control Models 1 and 2 and Integrated Storage Controls ...... « « « 132

A Guide to the IBM System/370 Model 158

SECTION 01: SYSTEM HIGHLIGHTS OF MODELS 1 AND 3

The System/370 Model 158 is an advanced function growth system for System/370 Models 145 and 155 and System/360 Models 50, 65, and 67. The Model 158 provides major new functions that are not basic to System/360 architecture. The Model 158 has new features, and new programming Systems Support that are designed to facilitate application development and maintenance. In addition, a Model 158 and its new programming Support can ease entry into, and expansion of, online data processing operations.

The Model 158 makes new functions available to Model 50, 65, 145, and 155 users without requiring a major conversion effort, since the Model 158 and its programming support are upward compatible with these models and their programming support. DOS Version 4, OS MFT, and OS MVT can be used on a Model 158. However, the Model 158 has standard features that are designed to support a virtual storage environment, and new versions of OS and DOS operating systems are provided that use these features.

Compatible growth from a System/360 operating system to a Model 158 virtual storage environment can be achieved using the System/370 operating systems: DOS/Virtual Storage (DOS/VS), OS/Virtual Storage 1 (OS/VS1), and OS/Virtual Storage 2 (OS/VS2), which are based on DOS Version 4, OS MFT, and OS MVT, respectively. These operating systems run only on System/370 models with extended System/370 functions; that is, on those with extended control mode of system operation and dynamic address translation facilities. They cannot operate on System/360 models. In addition to implementing virtual storage, the System/370 operating systems offer many other new capabilities and performance- oriented enhancements that are not provided by DOS Version 4 or OS MFT and MVT.

A virtual machine environment is supported by Virtual Machine Facility/370 (VM/370), the successor to CP~67/CMS for System/370. While CP-67/CMS is available only to Model 67 System/360 users, VM/370 operates on System/370 Models 135, 145, 155 II, 158, 165 II, and 168. Model 67 users who have CP-67/CMS installed can use VM/370 on a Model 158 with some conversion effort. The optional Virtual Machine Assist (VMA) feature can be installed on a Model 158 to improve the performance of certain operating systems that execute in a virtual machine under VM/370 control.

Transition with little or no reprogramming is provided for users who are emulating a DOS Version 3 or 4 environment under OS, a 1401/1440/1460/1410/7010 system under DOS or OS, or a 7070/7074 system under OS, as well as for users of 1400-series and 7070/7074 systems, Since the integrated emulators for these systems are also supported by the System/370 operating systems.

Two models of the Model 158 are provided. The Model 3 is an advanced version of the Model 1. The Model 3 has operational enhancements and CPU hardware features that give it improved availability and faster internal performance than the Model 1. The higher performance features of the Model 3 consist of hardware implementation differences in the Model 158 CPU (made possible by engineering design modifications and technology advances) and a larger high-speed buffer.

The performance features of the Model 3 do not require any programming

Support. Thus, programs that execute correctly on the Model 1 will execute correctly on the Model 3 without any programming changes,

A Guide to the IBM System/370 Model 158 1

assuming they have no timing dependencies and dado not access model- dependent logout areas that differ for the two models.

Highlights of the Model 158, Models 1 and 3, when compared with a Model 155, are as follows (features are the same for Models 1 and 3 except where stated otherwise):

¢ A basic control (BC) mode and an extended control (EC) mode of system operation are standard. Only BC mode is provided in the Model 155. EC mode of operation provides additional system control

and supports new functions that are not provided in System/360 or a Model 155.

e Internal performance of a Model 158 operating in BC mode is faster than that of a Model 155. The instruction execution rate of the Model 158 Model 1 is generally in the range of 20 to 50 percent faster than that of the Model 155 when identical system configurations, identical programs, and the same operating system are used. The increased internal performance of the Model 1 results from several improvements, among which are faster execution of several instructions and faster cycle times of processor storage in the Model i158.

The internal performance of Model 3 of the Model 158 is generally in the range of 5 to 11 percent faster than that of the Model 1 when identical system configurations, identical programs, and the same operating system are used. The increase in Model 3 internal performance is primarily due to the larger high-speed buffer it contains, implementation of a more effective buffer assignment algorithm, faster execution of certain frequently used instructions, and a faster read cycle time.

e Dynamic address translation (DAT) is a standard facility that can be made operative only when the Model 158 is in EC mode. It provides hardware translation of addresses during program execution. One virtual storage of up to 16 million bytes or multiple virtual storages of up to 16 million bytes each can be supported using DAT hardware. (The amount of virtual storage that can be efficiently supported by a Model 158 depends on the hardware configuration and job stream characteristics.) Channel indirect data addressing is also standard and is provided to handle I/O operations when dynamic address translation is used. Channel indirect data addressing enables the channels to access an I/O buffer that is contained in noncontiguous processor storage areas.

e Program event recording (PER) is standard and can be made operative when the Model 158 is in EC mode. It is designed to be used as a problem determination aid. This feature includes hardware that monitors the following during program execution: successful branches, the alteration of general registers, and instruction fetching from and alterations of specified areas of processor storage.

© A CPU timer and clock comparator are standard. The CPU timer provides an interval timing capability similar to that of the interval timer at location 80 but it is updated every microsecond, as is the time of day clock. The clock comparator can be used to cause an interruption when the time of day clock passes a specified value. These items provide higher resolution timing facilities than the interval timer and enable more efficient timing services routines to be written.

e New instructions that support dynamic address translation, the new

timing hardware, and system control facilities are added to the System/370 instructions available for the Model 155.

2 A Guide to the IBM System/370 Model 158

e Extended precision floating-point, 1401/40/60,1410/7010 Compatibility, 7070/7074 Compatibility, and OS/DOS Compatibility are no-~charge optional features. Extended precision floating-point and 7070/7074 Compatibility can be installed in the same Model 158. (They are mutually exclusive in a Model 155.)

¢ Processor storage is implemented using monolithic technology instead cf discrete ferrite cores. Processor storage sizes of 512K, 1024K, 1536K, 2048K, 3072K, and 4096K are available. Monolithic storage for the Model 158 is faster and more compact than core storage for the Model 155. The cycle time of processor storage varies from 690 to 1035 nanoseconds for a Model 1 and from 690 to 920 nanoseconds for a Model 3, depending on the operation performed, which is Significantly faster than the 2070~-nanosecond cycle time of processor storage for the Model 155. A four-megabyte Model 158 is a little more than half the size of a two-megabyte Model 155.

e The optional Power Warning featu~e, when installed on a Model 158 with uninterrupted power supplies, provides a warning machine check interruption when the utility-supplied power is approximately 18 percent below the rated voltage. Program support of this interruption, which is provided by OS MVT Releases 21.6, 21.7, and 21.8, OS/VS1 as of Release 3, and OS/VS2 as of Release 1.6, is designed to permit an orderly system shutdown after a power line disturbance occurs, when necessary, so that operations can be restarted once the power supply is stabilized.

e The high-speed buffer organization and assignment algorithms implemented in Models 1 and 3 of the Model 158 are different from those implemented in the Model 155. They are designed to enable the Model 158 CPU to fetch data from the buffer, instead of from processor storage, somewhat more frequently than does the Model 155 CPU. In addition, a 16K high-speed buffer is standard in the Model 3. The Model 155 and Model 1 of the Model 158 each have an 8K high- speed buffer.

Reloadable monolithic control storage, instead of read-only storage, is used for microprogram residence. Use of reloadable control Storage offers the advantage of improved microcode serviceability.

e A display console with keyboard and light pen are standard. The display console functionally replaces a console typewriter-keyboard and almost all the Lights and switches on the system control panel on the front of the Model 155 CPU. The display console is to be used by maintenance personnel as well as console operators. The display console offers faster operator-to-system communication via the light pen and faster message display than a typewriter-keyboard console when operating in display mode. When display mode is used, hard copy can be obtained, as an option, via the 85-cps 3213 Printer. The display console can also operate in printer-keyboard mode, which enables it to accept 1052, 3210, and 3215 printer- keyboard commands. The 3213 printer is required for printer- keyboard mode.

e The 3056 Remote System Console can he attached to a Model 158 via a cable up to 200 feet in length to provide a remote free-standing display console in addition to the standard display console on the Model 158 CPU. The optional 3056 Remote System Console provides a remote operator with almost all the functional capabilities as are provided by the standard display console.

®e The maximum aggregate data rate of five block multiplexer channels

operating concurrently in a Model 158 is 6.75 megabytes per second, compared with 5.4 megabytes per second in a Model 155.

A Guide to the IBM System/370 Model 158 3

Page of GC20-1754-2 Revised February 20, 1976 By TNL GN20-3580

e The byte and block multiplexer channels of a Model 3 can have more Shared and nonshared subchannels than can the channels in a Model 1 or the Model 155. In addition, a shared subchannel in the Model 3 can be shared by a maximum of 32 instead of 16 devices.

e 3330-series disk storage (all models) and/or 3340 direct access storage facilities can be attached to a Model 158 block multiplexer channel via the optional Integrated Storage Controls (ISC) feature as well as via 3830 Storage Control (Models 1 and 2). The ISC feature provides dual direct access storage control functions equivalent to two 3830 Storage Control Model 2 units, except for four-channel switching. Up to four strings of from two to eight drives each can be attached to each of the two logical storage comtrols in the ISC feature, for a total of eight 3330-series and/or 3340 strings (64 drives) attached via the ISC feature. Optionally, the staging adapter feature can be installed on the ISC to permit attachment of the 3850 Mass Storage System via ISC in addition to via 3830 Storage Control Model 3.

e The 3340 direct access storage facility can be attached to the Movel 158 via 3830 Storage Control Model 2 and the Integrated Storage Controls feature. The 3340 facility is intermediate capacity direct access storage that, because of its unique design and advanced technology, offers advantages over 2314 disk storage in addition to those provided by 3330-series disk storage. Automatic error correction features and multiple requesting are standard on the 3340. Rotational position sensing is optional.

The storage medium for 3340 disk storage is the removable interchangeable 3348 Data Module which is a sealed cartridge that is never opened by the operator. In addition to the disks on which data is written, the 3348 Data Module contains a spindle, access arms, and read/write heads. The 3340 Disk Storage Drive contains the mechanical and electrical components required to operate the 3348 Data Module.

The 3340 facility has an 885 KB/sec data transfer rate, average seek time of 25 ms, and full rotation time of 20.2 ms. A 3348 Data Module has a maximum capacity of approximately 35 million bytes or 70 million bytes, depending on the model. One model of the 3348 offers fixed heads for zero seek tire to approximately 502,000 bytes maximum and movable heads for an average seek time of 25 ms to the remaining bytes in the data module. 3A string of from two tc eight 3340 drives can be configured. From one to four 3340 strings can be attached to the 3830 Model 2 and to each of the logical controls in Isc. Any model of the 3348 can be mounted on a 3340 drive. Therefore, 3340 string capacity can vary from 70 million to 560 Million bytes in 35 and/or 70 million byte increments.

The sealed cartridge design of the 3340 facility offers the advantages of multiple capacities per 3340 drive, increased data reliability, and simplified data module loading and unloading procedures.

e 3344 Direct Access Storage can be attached to a Model 158 via 3830 Storage Control Model 2 and Integrated Storage Controls. It offers significantly increased maximum online capacity per drive for 3340 users without the necessity of program conversion. The 3344 is fixed media disk storage. Data is recorded on nonremovable disks. The 3344 is designed to eliminate operator handling, eliminate exposure to external contamination (like the 3348 Data Module), and provide high reliability.

—_

The 3344 has the same data transfer rate, average seek time, and full rotation time as the 3340. However, the maximum capacity of a

A Guide to the IBM System/370 Model 158

7,

Page of GC20-1754-2 Revised February 20, 1976 By TNL GN20-3580

3344 drive is 280 megabytes, or the equivalent of four 70-million- byte 3348 data modules. The 3344 is a two-drive unit that attaches to the 3340 Model A2. A 3340/3344 string can contain any mixture of 3344 and 3340 units (as long as the first is a 3340 Model A2) for a taximam of eight drives with a maximum capacity of over 1.8 billion bytes.

Automatic error correction, rotational position sensing, and multiple requesting are standard in the 3344. Fixed head models that contain fixed heads for zero access time to a portion of the data and movable heads for access to the balance of the data are also available.

e 3350 Direct Access Storage can be attached to a Model 158 via 3830 Storage Control Model 2 and Integrated Storage Controls. The 3350 is very large capacity, high-speed, fixed media direct access storage. Data is stored on nonremovable disks. The 3350 is designed to eliminate operator handling, eliminate exposure to external contamination, and provide high reliability.

The 3350 has a data transfer rate of 1198 KB/sec, average seek time of 25 ms, and full rotation time of 16.8 ms. A 3350 drive operating in native mode has a maximum capacity of 317.5 megabytes. A 3350 string can contain from two to eight drives in two drive increments for a maximum string capacity of over 2.5 billion bytes of online disk storage.

The Standard Selective Format feature enables the format of each 3350 to be set by programming during volume initialization. A 3350 drive can operate in 3350 native mode, 3330 Model 1 compatibility wode, or 3330 Model 11 compatibility mode. When operating in 3330 Model i compatibility mode, a 3350 drive is the equivalent of two 3330 Model 1 drives in capacity. When operating in 3330 Model 11 compatibility mode, a 3350 drive is the equivalent of one 3330 Model 11 drive in capacity. This feature enables 3330-series user to obtain the price performance and functional advantages of the 3350 without program conversion.

Automatic error correction, rotational position sensing, and multiple requesting features are standard. The 3350 is also available in fixed head models. These models provide fixed heads for zero access time to a portion of the data and movable heads for access to the balance of the data.

e A remote support facility (RSF) utilizing the standard service processor unit, not provided for the Model 155, is standard for the Model 158. RSF enables a customer engineer specialist at a remote location (System Support Center) to execute diagnostics and assist in locating hardware failures in a Model 158. This may eliminate the necessity of a trip to the installation by the customer engineer specialist. RSF is designed to improve system availability by reducing the amount of time required to locate hardware failures.

The Model 158 is designed primarily to support a virtual storage environment which allows programmers to write and execute programs that are larger than the processor storage available to them. When virtual Storage is supported, restraints normally imposed by the amount of processor storage actually available in a system are eased. The removal of certain restraints can enable applications to be installed more easily, and can he valuable in the installation and operation of online applications. While some of the new hardware features of the Model 158 and some of the new facilities supported by System/370 operating systems are designed to improve performance, a virtual storage environment is designed primarily to help improve the productivity of data processing personnel and enhance the operational flexibility of the installation.

A Guide to the IBM System/370 Model 158 5

SECTION 10: PHYSICAL DESIGN AND SYSTEM TECHNOLOGY FOR MODELS 1 AND 3

The System/370 Model 158 is shown in Figure 10.1. It ia8 air coole? and similar in physical appearance to the Model 155 except for the conscle panel on the front of the Model 158 CPU frame and the display console. <A Model 155 cannot be converted to a Model 158.

Figure 10.1. System/370 Model 158 (design model)

The physical size of Models 1 and 3 of the Model 158 is the same. the physical size of a Model 158 with more than 512K of processor storage is significantly smaller than the size of a Model 155 with more

6 A Guide to the IBM System/370 Model 158

td

than 512K as a result of the implementation of monolithic, instead of Magnetic core, processor storage. Processor storage is contained within the CPU frames of the Model 158. A 512K Model 158 is a half frame larger than a Model 155 with 512K because of the additional hardware features of the Model 158. The two models are the same height. The Size of a Model 158 is the same regardless of the amount of processor storage installed. A four-megabyte Model. 158 is a little more than half the size of a Model 155 with two megabytes of processor storage.

Monolithic technology is used to implement all logic and all storage (processor, local, control, and buffer) in the Model 158. Use of monolithic technology for processor storage, as well as for logic, represents a Significant technological advance in storage implementation. The monolithic storage implemented in the Model 158 provides several advantages over the wired, discrete ferrite core storage implemented in the Model 155.

Monolithic storage is Similar in design to monolithic logic circuitry, the latter representing a technological advance over the solid logic technology (SLT) introduced with the announcement of System/360. Since the technology associated with monolithic storage is like that used to produce monolithic Ogres monolithic storage can be batch-fabricated.

Solid Logic Technology (SLT)

Monolithic technology is a breakaway from the hybrid circuit design concept of SLT and can best be explained by comparison with SLT. As shown in Figure 10.2, SLT circuits were implemented on half-inch ceramic Squares called substrates. Metallic lands on the substrate formed interconnections onto which the components were soldered. These components consisted of transistors and diodes, which were integrated on Silicon chips about the size of a pinhead, and thin film resistors. An SLT chip usually contained one type of component, and several chips and resistors were needed to form a circuit. In general, an SLT substrate contained a single circuit.

SLT chip with

one component Ceramic substrate

with interconnections

Figure 10.2. SLT substrate

Monolithic System Technology (MST)

Monolithic system technology also makes use of a half-inch-square ceramic substrate with metal interconnections onto which chips are placed. However, in monolithic logic circuitry, large numbers of elementary components, such as transistors and resistors, are integrated on a Single chip. Unlike an SLT chip, an MST logic chip usually contains several interconnected logic circuits instead of only one component. MST logic modules, each consisting of one substrate, are

A Guide to the IBM System/370 Model 158 7

mounted on circuit cards, which are in turn mounted on circuit boards (as in SLT logic).

MST logic offers the following advantages over SLT:

e MST logic circuitry is intrinsically more reliable because many circuit connections are made on the chip, significantly reducing the number of external connections,

e Faster circuit speeds can be obtained because the path between circuits is considerably shorter.

e Space requirements for logic circuitry are reduced by the Significantly higher density of components per chip.

Monolithic Storage

Monolithic storage design incorporates the same concepts described for monolithic logic. However, storage cells that are used to contain storage bits instead of logic circuits are implemented on a metal oxide semiconductor chip. In the Model 158, a monolithic storage array chip is approximately 1/8 x 3/16 of an inch in size and contains a large number of interconnected circuits. These circuits form storage bits and Support circuitry (decoding, addressing, and sensing) on the chip.

Since power is required to maintain a one or zero state ina monolithic storage bit, data is lost when power is turned off, and monolithic storage is, therefore, said to be volatile. This is not true of core storage, which retains a magnetized state when power is removed.

The following are the advantages of monolithic over core Storage:

e Faster storage speeds can be obtained, first, because of the shorter paths between storage circuitry and, second, because of the nondestructive read-out capability of monolithic storage. Since core storage read-out is destructive, a regeneration cycle is required after a read and is also used before a write. This type of regeneration cycle is not required for monolithic storage.

¢ Storage serviceability is enhanced because storage is implemented in accessible, easily replaceable storage cards. Diagnostic routines need only identify the failing storage card, which can be replaced in a matter of minutes.

e Space requirements for system storage are reduced. Dense bit packaging per