Vintage IBM Computers

My PC Thinks It's A Mainframe

Mainframe computers started to appear in the early 1960's as transistor technology superseded vacuum tube machines. Vacuum tube computers could never really get big as the size of a tube combined with the power it used and heat if put out made truly large computers impractical. This was a special time in world history as the Space Race was really heating up. If you were coming of age or a young adult during this period there was a unique sense of unlimited possibilities. As the 60's progressed and turned into the 1970's integrated circuits, the ability to etch multiple miniature components on a small silicon wafer, caused an explosion in processing power and a collapse in computing costs. International Business Machines (IBM) quickly dominated the business sector of data processing. They gained the nickname "Big Blue" for the large deep blue metal cabinets that made up their computers. As disk space at this time cost over $100 a megabyte and main storage (RAM) was over $100 kilobyte operating systems had to be direct and to the point. Great effort was put into getting the most thru-put and production from the smallest amount of ram and disk space possible. By 1980 three IBM operating systems had matured from earlier work to become true workhorses. All three have evolved into present-day offerings of Z/OS, Z/VSE, and Z/VM. For those that worked with this impressive computing equipment from the early days it is amazing that modern PC's can emulate the instruction sets of the old computers and thus run MVS Rel 3.8J from 1980, DOS/VS Rel 34 from 1974, and VM370 Rel6 from 1978 at speeds the old machines could never match. See below the live consoles of the OS's I run for public internet use on several old PC's in my home.

This site is concerned mainly with how to use your PC to run the vintage IBM operating systems that are legally available without license issues. Most people are not aware that until Congress passed a new law in 1981 that most prior software has no copyright protection. Whether for fun or educational purposes you can program in COBOL, FORTRAN, PL/I, GPSS, ALGOL68 and many other languages. You can use tape drives (emulated or REAL), 3270 type terminals (emulated or REAL), and view your results in a text editor or print them out complete with green/gray bars if you wish. There are a few locations that are using these old operating systems for actual production purposes but most people are hobbyist or students. A lot of IBM old timers enjoy being able to continue to work with the software they have used most of their career.

Then Came the Personal Computer

In August of 1981 IBM introduced it's personal computer developed at a facility in Boca Raton, FL. Up until now small computers (microcomputers) had not been taken seriously. The fact that the 600 pound gorilla in the computer marketplace had decided to offer a pc was a watershed moment in computing history. The model number was 5150 and it was paired with a 5151 green monochrome or 5153 color monitor. IBM openly published the specifications for the machine which lead to an explosion of third party accesories and clones from new start-up companies, driving the stock market nuts into the early 1990's. Having your own PC in your home became the hot ticket as modems (modulator-demodulator) connected to the telephone system opened up online computing, email, and special interest forums/groups. A lot of the applications and games were text based giving them a unique character that is lost in todays graphics heavy environment.

Performance growth was phenomenal, starting at a data width of 8 bits and climbing thru 16, 32, and finally 64 bits today. Speeds went from a pokey 2 megahertz to an astounding 4 gigahertz today. Memory went from 64 kilobytes (considered large at the time) to a point where 8 gigabytes is considered normal. When operating systems progressed and left the ability to run original DOS (Disk Operating System) programs behind hobby groups created emulators so they could continue to play the old games. One such emulator is DOSBox.

The myMainFrame DVD Package

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All six of the GUI's below are available on a single DVDROM with additional SYSGEN and documentation materials (over 4GB worth) thru ebay with the renown ebay buyer protection plan for only $39.95 with free shipping to the US. Just click on the DVD image.

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myMVS Screenshots

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Stand By  -  Connecting to Terminal Server

Stand By  -  Connecting to Terminal Server


MVS Rel 3.8J

The IBM operating system MVS was the most commonly used on the System/370 and System/390 mainframes. It's acronym stands for Multiple Virtual Storage. It was a logical progression from MFT which ran jobs in predefined partition sizes. The version 3.8J is the last version that was made available to the public free of charge and can be run on a PC without license issues. The major restriction of this version is it is limited to 16Mb main memory to be split among all tasks. Later licensed versions of this OS used 31 bit addressing instead of 24 bit. This operating system was designed primarily for batch processing of large amounts of customer billing and account information. It would not be unusual for a small shop to process and print 30,000 customer bills a night every week night. MVS does include TSO (Time Sharing Option) which was an early development in making computers interactive and responsive to transactions as they happen.

myMVS Screen Shots


Test Drive An IBM TSO User Logon

Play SuprTrek, one of the first computer games.

MVS 3.8J and Google Gotcha's
Glossary Common Messages White Papers
Console Commands How To's MVS Control Files
Websites of Interest Vintage MVS Books Assembler Tutorial
Downloads RFE Help File as .txt Forum Messages - WIP
Help With Prgram ABEND Codes KICKS For TSO .

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myVM370 Screenshots

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VM (often: VM/CMS) refers to a family of IBM virtual machine operating systems used on IBM mainframes System/370, System/390, zSeries, System z and compatible systems, including the Hercules emulator for personal computers. The first version, released in 1972, was VM/370, or officially Virtual Machine Facility/370. This was a System/370 reimplementation of earlier CP/CMS operating system. Milestone versions included VM/SP.[1] The current version is z/VM, and is still widely used as one of the main full virtualization solutions for the mainframe market. VM's differences with other IBM mainframe operating systems are primarily due to the unique circumstances in which CP/CMS was built and distributed. [1] The latest public domain version of this OS is release 6 which was made available in 1979.


myVM370 Screen Shots


Test Drive An IBM CMS User Logon

Glossary Common Messages .
Console Commands How To's VM Control Files
Websites of Interest Vintage VM/370 Books Mainframe Photo Gallery
VM Editor Reference Using the 3270 Terminal *

myDOSVS Screenshots

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DOS/VS with POWER Rel 34

DOS/VS Rel 34 is one of the mainframe OS's you can run on your PC. It was introduced in 1974, an upgrade from the first DOS/VS which came out in 1972. The DOS/VS operating system was a continuation of DOS/360 which was a stop gap measure after the introduction of the System/360 computer. IBM had intended for it's customers to migrate to OS/360 when it was released, but many had invested to heavily in DOS/360 to abandon it. So DOS/VS continued as a separate product and eventually developed into DOS/VSE then VSE/SP onto VSE/ESA and finally z/VSE the last release of which was in 2005. The Rel 34 version of the operating system, when run on a modern PC with an emulator, convincingly outperforms the original mainframes that it was developed for. To boot DOS/VS on an 1980's era computer often took more than 15-25 minutes but the Hercules emulator will boot it in less than 1 minute on my old 1.8Ghz spare PC.


myDOSVS Screen Shots


Glossary Search System Messages Downloads
Console Commands How To's DOS-VS Control Files
Websites of Interest Vintage DOS-VS Books Mainframe Photo Gallery
Forum Messages - WIP myDOSVS Manual *

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DOS/360 Rel 26.4

myDOS360 Screenshots

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DOS/360 Rel 26.4 was at it's inception the only available operating system for the new System/360 introduced in 1964. In this era of transistion from vacuum tube to transistor computers this was the only control program that could be considered complex enough to be called an operating system in the modern sense of the phrase. This was the first serious commercial machine to try and address both scientific and business applications. It was a resounding success and transitioned many manual accounting offices into the computer age as well as providing revolutionary computing power to many a science and research project that was simply unavailable before the System 360 came on the market. It was the main computing force behind the Space Race of the 1960's. Without it the US would certainly not won the competition to reach the Moon first.

The two primary languages were COBOL and FORTRAN with a lot of work done in the very low level assembler.


myDOS360 Screen Shots


Glossary Search System Messages Downloads
Console Commands How To's DOS/360 Control Files
Websites of Interest Vintage DOS/360 Books Mainframe Photo Gallery
Forum Messages - WIP myDOS360 Manual *

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MVT Release 21.8F

MVT (Multiple Variable Tasks) and it's slightly smaller brother MFT (Multiple Fixed Tasks) were derived from the OS/360 offering that followed DOS/360. IBM intended for shops to give up DOS/360 and switch to MVT or MFT but a lot of them had invested to much in DOS/360 development to just change to an operating system that was not backward compatible. So only the big companies that needed the greatly increased power of the new OS's switched over. MFT wound up being only a foot note as not to many people ran it, MVT was the big boy OS at the time.


myMVT Screen Shots


Glossary Search System Messages Downloads
Console Commands How To's MVT Control Files
Websites of Interest Vintage MVT Books Mainframe Photo Gallery
Forum Messages - WIP myMVT Manual *

myMTS   - MTS 6.0A -   ebay Item
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MTS Release 6.0A

MTS (Michigan Terminal System) WIP WIP WIP WIP WIP


myMTS Screen Shots


Test Drive An MSU MTS Student Logon

Glossary Search System Messages *
Console Commands How To's MTS Control Files
Websites of Interest Vintage TSS Books Mainframe Photo Gallery
Forum Messages - WIP myMVT Manual *

Available Online Compilers On This Site

I have setup a number of vintage compilers that you may use. Below is a brief description and link to each one.


Online ALGOL F Compiler

ALGOL stands for ALGOrithmic Language. Devlopment was started in the mid 1950s to solve issues with the FORTRAN that was available at the time. It is primarily a language for solving mathmatics problems. ALGOL F was introduced for the IBM/360 line of computers in the 1960's.


Online ALGOL 68C Compiler

This particular version of ALGOL was released in 1996 and is considered the gold standard of those compilers that run on a vintage operating system.

Assembler F

Online Assembler F Compiler

Assembler F followed BAL (Basic Assembler Language) in the early days of the System/360. It in turn was followed by Assembler G, Assembler H, and today we have HLASM still available for current day mainframes.

Assembler System for Student Instruction & Systems Teaching

ASSIST Student Assembler

ASSIST is a high-speed interpreter for teaching IBM/360 assembler that has extended error and diagnostic messages and condensed dumps to help the begining student.



BASICUM was developed by the University of Michigan for the MTS operating system that served the state wide campuses of the University of Michigan up untill 1999.


Online COBOL F Compiler

COBOL stands for COmmon Business Oriented Language and as you guessed is primarily used for business, finance, and goverment administration. This is version 2 level 78 from May of 1972.


Online FORTRAN F Compiler

FORTRAN stands for FORmula TRANslator and was oringinally developed in the mid 1950s. This version was developed for the venerable IBM System/360 in the 1960s. The language was created for science and mathmatics use.


Online GPSS/360 Compiler

GPSS is a simulation language that was first developed in the 1960's. This is the GPSS/360 version that is available via the Michigan Terminal System operating system (MTS) developed starting in 1967 at the University of Michigan, the last system using it was shutdown in 1997.


Online MORTRAN Compiler

MORTRAN is a version of FORTRAN which allows greater flexibility in keying the source file. Free form is allowed to some extent and labels may be alpha-numeric. The program listing has an auto-indentation feature.


Online PASCAL 8000 Compiler

PASCAL 8000 was developed by Kiyoshi Ishihata and Teruo Hikita at the University of Tokyo and modified by Jeffrey Tobias and Gordon Cox at the Australian Atomic Energy Commission. It outputs in the 360 object file format directly without going through an assembler and linker.


Online PL/I Compiler

PL/I stands for Programming Language One and was created to be effective at engineering, scientific, business, and systems programming. Kind of a universal language. This version was developed for the IBM System/360 in the 1960s.


Online PL360 Compiler

Devloped at Stanford and designed by Niklaus Wirth, PL360 combines both assembler specification of instructions and registers with complex math expressions and higher level control structures such as loops and if-then constructs. It first appeared around 1967.


Online RPG Compiler

RPG stands for Report Program Generator and was used extensively in business. It was designed so that non-programmers could use it to easily produce reports with out the need of an experienced programmer which were in short supply and high demand in the 1960s and 1970s. Unlike other languages you selected items you desired out of a fixed procedure to obtain your printout.


Online SIMULA Compiler

SIMULA is one of the early simulation languages used on mainframes. It was created by Ole-Johan Dahl and Kristen Nygaard at the Norwegian Computing Center in Oslo in the 1960's. It's second version introduced virtual methods, classes and sub-classes, and objects. It was an important step forward that infuenced the development of C++ and Java.


Online SNOBOL4 Compiler

(StriNg Oriented and symBOlic Language) SNOBOL is used to mainipulate strings, do pattern matching, and construct code segments that can be executed. It was developed in the 1960's and in the second half of the 1960's and first half of the 1970's it was widely taught at US universities. AT&T's renown Bell Labs was it's birth place, developed by Ivan P. Polonsky, Ralph E. Griswold and David J. Farber.

Stony Brook Pascal

Online Stony Brook Pascal Compiler

This compiler was developted at the State University of New York at Stony Brook with the compilers compiler XPL for the IBM System/370 computer.


The powerful Hercules emulator is what allows us to run a mainframe operating system on a PC. It is open source and runs on Windows, Mac OSX, and Linux machines. It will even run on a Rasberry PI. The offical website is located here. While there are other OS's that can be run with Hercules, the most popular 3 are DOS/VS, MVS, and VM/370. This is a great hobby for retirees that had hands on experience with these operating systems in the 1960's and 1970's.

Other OS's for Hercules use

A useful table of
EBCDIC, ASCII, Hex, Decimal, & Octal

IBM Mainframe Glossary

General Computer Glossary

Great Vintage Computer Museums

Using Vintage IBM Hardware With Your PC

Videos on vintage IBM and CDC mainframes

IBM Photo Gallery

Hercules GUI's for PayPal Purchase and Immediate Download

New WIP - A 3270 emulator (x3270, Tn3270) Scratch Pad

All Hercules OS's Default Passwords

Can I cut open an Ocuvite capsule?

Tips and Tricks for PC Programming

Bearing and Distance to TV Transmitters

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