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MVS Version Names - Make sense of the versioning confusion

MVS Version Names MVS 3.8 from the TK4 distribution is what we know best. But often there is a misguided understanding that later versions are improvements and therefore better versions of MVS. That is not always true, and often not how IBM released software. In the beginning After the OS/360 (MFT and MVT) start, IBM released OS/VS2 rel 1, as the next version. That name, OS/VS2 stuck to this very day. Every subsequent release was an OS/VS2 operating system. OS/VS r1 was also called SVM, for Single Virtual Memory. Quickly after IBM renamed that to SVS, Single Virtual Storage. Why the change from "memory" to "storage"? Because IBM had decided to switch with the last S/370 mainframes from core memory to solid state storage instead. SVS was mainly geared at solving real memory fragementation. MVS In the mid 1970s, (1973 to be exact) IBM annoucned MVS. This very important new operarting systems, now allowed each application to have its own full 16MB address sp
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Old, old software

Lately, a bunch of 3420 tape reels were found. After converting them into electronic format, we unearthed several software products that were thought to be lost forever: 1. EDGAR 2. 5740-CB1 RELEASE 2.4 IBM OS/VS COBOL JULY 1, 1982 for MVS This is the follow-on release to the MVT Cobol that we know from MVS 3.8 TK4-. Both are ANSI Cobol compilers, but this one has a several novelties compared to the Release 1.3 of TK4-: an optmizer, VSAM support, a LIST parameter to create an assembler listing, and better RENT checking. 3. CP/67 CMS Source code See more here:
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BITNET - NJE - HNET Long before the Internet, there was the BITNET, a collection of mainframes and mini-computers (such as VAX machines) inter-connected to each other by means of IBM's NJE (ie Network Job Entry) protocol.  Most of the connections were over modem dial-up lines at speeds of 300 bauds or sometimes 1200 bauds. Some of the links were leased lines at 64kbit, even.  The BITNET was an academic network and only universities were allowed to connect to the network.  IBM's VNET network was built on the same protocol, same interconnects but was distinct from BITNET. However, there were some gateways between BITNET and VNET.  At one time over 5000 mainframes and time-sharing computers were connected to BITNET by means of NJE.  In 2019 the mainframe enthusiast community revived the BITNET network by using the same protocol and the Hercules mainframe emulator. Some VAX machines connected using an NJE protocol implementation for openVMS. As of the time of this blog post, over 1
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Web Server on z/VM So, let's grab Apache or NGINX and compile on z/VM, right? Well, not that easy. It's almost impossible to compile those open source web servers on z/VM. However, one can write a web server in REXX. This guy uses such a Rexx-based webserver and shows in a video where to obtain it, how to set it up and even how to write Rexx CGI scripts! Check it out
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The Real Thing How did it feel back in the days to work on a real mainframe? I am not talking about the modern z14 and z15 mainframes of today. I am talking about the 3090's and 4381s of the mid-80s, the golden era of the mainframe. Well, only one way to find out: log in to a real IBM 4361 mainframe and play it... and make a video out of it. This guy made just such a video Fun video, go check it out
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Rexx on MVS 3.8 Now Available In this video I show how to obtain, install and use Rexx (the BREXX kind) on our beloved MVS 3.8 TK4. It's easy peasy, so go watch the video and get running with Rexx!
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Disassembling Stuff is Fun

I have always been fascinated with assemblers and disassemblers, maybe because my very first programming was in machine code on 8080 computer (thru the front panel switches!!). I have tons of videos about assmembler programming on the mainframe for both z/OS and for MVS (on Hercules) here.  In this video however, I show how to disassemble binaries to find out how they were programmed. Lots of fun with disassembling stuff recently, but then I wanted to try to disassemble binaries in MVS 3.8 TK4- on Hercules and I couldn't find a good disassembler. After a long search and some minor hacks I got it to work. check out this github repository I created. This amazing disassembler works. Here is the README of the repository below. I shall shortly release a video about the installation and operation of this disassembler. mvs38dasm This is a re-share of Gerhard Postpischil's simply amazing S/360 and S/370 disassembler for MVS3.8 What it is It has become somewhat diffi
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