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July 30, 2020

How OpenVMS Escaped the MPE/iX Fate

Fire escape

Photo by thr3 eyes on Unsplash

01:31 PM in History, Homesteading | Permalink | Comments (0)

July 27, 2020

Fewer voices fill the 3000's air

Mic in studio on air
Photo by Fringer Cat on Unsplash



July 20, 2020

25 Years: Surviving beyond HP's wishes

Pontiac survivor plate









Image by rjlutz from Pixabay

08:56 AM in History, Homesteading, News Outta HP | Permalink | Comments (0)

July 17, 2020

Logon advice launches new 3000 admin crop

Row of Lettuce
By George Stachnik




Logging on








When you've entered all the necessary passwords, the HP 3000 will display a message that identifies the system you've logged on to (called the "Welcome Message" in MPE-speak) and log you on to the system.

What happens next depends on how your system has been set up. Frequently, system managers configure their HP 3000s so that menu programs or applications are executed automatically upon logon, and exiting those applications causes you to be automatically logged off the system. You never interact with the operating system directly. So if you log on to a 3000 and are suddenly confronted with an application program, a system manager has set up your particular user and account to work that way. 

User and Account Name

Ordinarily, the system displays a prompt on your screen that ends with a colon (:). This is the HP 3000's way of prompting you for an MPE command. I'm going to explain a few of the most basic and frequently used MPE commands, and at the same time explore some of the basic concepts and ideas behind MPE.

I'll begin by raising a few questions about your user and account name (the two parameters you entered in order to log on). Why are there two? After all, you need only one name to log on to a Unix machine. Why does the 3000 require two logon names?

To answer that question, we need to explore how HP 3000s (and most other minicomputers) were used in 1972, when MPE/iX was originally designed. In those days, computers (even HP 3000s) were very expensive--too costly for most small-to-midsize companies to own. Personal computing was more than a decade away, so (capitalism being what it is), an industry called "time-sharing" had sprung up. You might be thinking, "I thought that time-sharing had something to do with vacation homes." But in the early 1970s, time-sharing companies purchased computers (such as HP 3000s) and allowed other companies to share them (in exchange for a fee).

Here's how it worked. Imagine you're the owner of a time-sharing business. You buy an HP 3000, and provide your clients (the owners of small businesses who don't have computers of their own) with terminals and dialup lines so they can share your computer. They installed their applications on your machine, and at the end of each month you'd bill your clients based on how heavily they used your computer. As you can see, it becomes very important to be able to track who was doing what with the machine.

What does all this have to do with the account and user ID you entered when you logged on? Suppose your time-sharing company had signed contracts with three clients: Tom's Dry Cleaners, Harold's Used Cars, and Dick's Bar and Grill. You might set up three accounts on your system and call them something like TOM, HAROLD, and DICK.

On the HP 3000, accounts are tools for keeping track of who is using the system's resources--CPU time, memory, disk space, and so on. For example, each account has a timer associated with it. When somebody logs on to an account, that account's timer begins ticking like a taxi meter.

When the TOM account's meter begins ticking, Tom's Dry Cleaners is charged for the time you spend on the machine. (To see how you can use MPE commands to display these "taxi-meter" timers, see the sidebar called "Listing Accounts and Users.")

But what if one of the time-sharing company's accounts requests a detailed breakdown of its bill? Suppose, for example, that Harold's Used Cars employs three salesmen named Moe, Larry, and Curly. (Hey, I didn't say it was a good used car company.) When Harold gets his bill at the end of the month, he's probably going to want to know what portion of it is can be traced back to the activities of each of his salesmen.

MPE requires that when Moe (or any other user) logs on to the system, he doesn't just log on as "MOE" or as "HAROLD" but as "MOE.HAROLD", specifying both his user name and his account name. In this way, Moe actually kicks two timers into action. One is associated with the HAROLD account and accumulates all the time logged by any and all HAROLD users. The second is associated with MOE.

Each HP 3000 account has a password to protect it from unauthorized usage. Each account also has a number of users associated with it, and each also has (or at least should have) a password of its own.

Each user name is associated with one and only one account. In other words, you cannot log on to an account unless you have a userid that belongs to that account. For example, Moe works for Harold's Used Cars. Therefore, his username has been tied to the HAROLD account, and he must log on as "MOE.HAROLD". He can't log on as "MOE.TOM" or "MOE.DICK".

In this sense, each account can be thought of as being a collection of related users. MPE accounts are similar, in this respect, to Unix Group IDs, or GIDs. MPE systems have a number of concepts in common with Unix systems, although the terminology and details often differ.

Photo by Kenan Kitchen on Unsplash


July 15, 2020

Automated messages track 3000's orbit

Satellite ISS






Image by Free-Photos from Pixabay

07:46 PM in History, Homesteading | Permalink | Comments (0)