How is it possible to connect a mainframe with a PC running Windows? [closed]

Asked 7/1, 2009 at 11:37 Answered 12/1, 2009 at 13:12

How is it possible to connect a mainframe with a PC running Windows?.Is it still regarded a mainframe as a computer with a high processing power running Unix or IBM System360

Harmattan answered 7/1, 2009 at 11:37 Comment(2)

Matthew Broderick used a modem. – Elastin 15/6, 2009 at 3:58

I don't think this question is off topic as Microsoft has released Host Integration Server 3270 Design Tool for Windows 10, Windows Server 2016, Windows Server 2019 microsoft.com/en-us/download/details.aspx?id=57962 – Summons 27/12, 2020 at 22:25

We do it every day. You can connect to the OMVS/USS (UNIX system services) subsystem using standard telnet or ssh (if the mainframe has had that set up) but, to access the z/OS interface (TSO/E or ISPF), you'll need a 3270 emulator such as x3270 (we use IBM's Personal Communicator product because it's incredibly powerful).

The mainframe is in no danger of disappearing anytime soon. There is still a large amount of work being done at the various IBM labs around the world and the 64-bit z/OS (nee MVS, nee OS/390, ...) has come a long way.

It's still used in the big corporations as it's the only thing that can be trusted with their transactions - the z in System z means zero downtime and that's not just marketing hype. The power of the mainframe lies not in it's CPU grunt (the individual processors aren't that powerful but they come in books of 54 CPUs with hot backups, and you can run many books in a single System z box) but in the fact that all the CPU does is process instructions.

Everything else is offloaded to specialist processors, zIIPs for DB2, zAAPs for Java workloads, other devices for I/O (and I/O is where the mainframe kills every other system, using fibre optics and very large disk arrays). I wouldn't use it for protein folding but it's ideal for where it's targeted, massively insane levels of transaction processing.

z/OS has a UNIX subsystem and z/VM can run multiple copies of z/OS, other z/VMs and even zLinux (RHEL & SLES) - I've seen a single z800 box running thousands of instances of RHEL concurrently. This puts all the PC manufacturers 'green' claims to shame and communications between the instances is blindingly fast with HyperSockets (TCP/IP but using shared memory rather than across slow network cables (yes, even Gigabit Ethernet crawls compared to HyperSockets (and sorry for the nested parentheses :-))).

It runs Websphere Application Server and Java quite well in the Unix space while still allowing all the heritage stuff to run as well. In fact, mainframe shops need not buy PC-based servers at all, they just plonk down a few zLinux VMs and run everything on the one box.

And recently, there's talk about that IBM may be providing xSeries (i.e., PCs) plugin devices for their mainframes as well. While most mainframers would consider that a wart on the side of their beautiful box, it does open up a lot of possibilities for third-party vendors. I'm not sure they'll ever be able to run thousands of Windows instances but that's the sort of thing they seem to be aiming for (one ring to rule them all? :-).

If you're interested, there's a System z emulator called Hercules which I've seen running at 23 MIPS on a Windows box (barely enough grunt to start ISPF for your mainframers out there) but it runs the last legally-usable MVS 3.8j fast enough to get a feel.

To provide a shameless plug for a book one of my friends at work has just written, check out What On Earth is a Mainframe? by David Stephens (ISBN-13 = 978-1409225355). I found this invaluable since I came from a PC/UNIX background, and it is quite a paradigm shift.

Helenhelena answered 7/1, 2009 at 11:53 Comment(3)

Wow. Thanks for an informative, insightful and well written answer. – Durwin 7/1, 2009 at 18:9

Thanks for the informative response. I am looking for at a WebSphere-mainframe (IMS) access. I came across IMS TM Resource Adapters - are they the xSeries plug-ins that u have mentioned above? Would i be able to write "SQL" in my J2EE apps to fetch data from mainframes ? – Narcotize 19/8, 2009 at 17:24

@Subramanian, JDBC drivers generally connect through to DB2/z, not IMS (IMS is not a relational DB). But there is a product available which puts a DB2-SQL skin on top of IMS - whether you can get DRDA (the low-level stuff used by DB2 JDBC drivers) working to it is another matter. I have no idea. – Helenhelena 25/8, 2009 at 4:39

We use a piece of software called Rumba for this.

Betulaceous answered 7/1, 2009 at 11:40 Comment(0)

A mainframe would normally refer to "big iron" machines like IBM's zSeries. The best way to connect to a machine like that is with a 5250 emulator. There are several open-source / free emulators available which run on Windows, linked to from that page.

You can normally telnet or SSH into the machines, but into some sort of UNIX emulation which hides the true power of the native OS. If you're actually running UNIX directly on a slice of the hardware (like zLinux for example), then SSH should be fine.

Nice answered 7/1, 2009 at 11:46 Comment(1)

You probably mean 3270. 5250 is for connecting to the iSeries (formerly AS/400) machines. – Maintopmast 9/1, 2009 at 4:37

For an IBM z Series, 390 or its predecessors use a 3270 emulator.

For an IBM AS/400, iSeries, use a 5250 emulator.

For Unix, VMS and most other systems, use telnet or ssh.

Tympany answered 7/1, 2009 at 11:57 Comment(0)

You can also use IBM's rational developer tools to connect to a mainframe. They provide an eclipsed based GUI that allows you to do things such as edit source stored in mvs datasets, submit and view jobs, and debug programs with a GUI. I've used it before and it was much easier for me to use then ISPF but I'm also a college student with very little ISPF experience and a lot of eclipse experience. See this link for more info. http://www-01.ibm.com/software/awdtools/rdz/

Justin answered 12/1, 2009 at 13:12 Comment(0)

Telnet or SSH.

Roulade answered 7/1, 2009 at 11:41 Comment(0)

Yes you can. Mainframes speak TCP/IP and they are used as webservers.

You can also use a terminal emulator.

System360 is called zOS if I'm correct.

Tanah answered 7/1, 2009 at 11:48 Comment(2)

System 360 was the hardware (which is now System z). The OS has been called OS/360, OS/390, MVS and now z/OS. – Helenhelena 7/1, 2009 at 11:55

O yes, the last mainframe job was almost 8 years ago. – Tanah 7/1, 2009 at 12:50

MochaSoft sell a relatively low-priced Telnet3270 emulator, plus a lot of other terminal emulation stuff. Generally lighter-weight and more friendly than the mainstream suppliers (IBM, Attachmate, etc.)

Equi answered 7/1, 2009 at 13:9 Comment(0)

-1

Hyperterminal and a long RS232 cable should do the trick. Depends also to some extent on whether the IBM can do ASCII or is limited to EBCDIC.

Gaulish answered 7/1, 2009 at 11:45 Comment(0)

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