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Computers before operating systems

by Avichal
Tags: computers, operating, systems
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lpetrich
#19
Sep25-13, 12:27 PM
P: 518
As harborsparrow mentioned, a smart terminal is one that interprets certain character combinations as commands to move the cursor, clear a line, clear the screen, format the text, etc. -- those

One can create ASCII-art GUI's using these escape sequences, like for text editors and games.

Smart terminals are still common, though in virtual form. I mainly have experience with SunOS and OSX, but their terminal apps create smart virtual terminals.


As to present-day OS-less computers, I'd imagine that some small embedded ones are OS-less, but that's about it.
harborsparrow
#20
Sep25-13, 01:05 PM
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To get down to brass tacks, "smart terminals" were really computers themselves. They contained a microprocessor--a big deal in the 1980's--that would allow, via the entry of control codes from a keyboard, a certain amount of local editing of commands before sending entered commands (usually serially) off to a remote processor for execution on "a mainframe" or "a real computer".

I'm talking about, say, the 1980's here.

ANSI VT100 is a standard dictating one way in which a smart terminal could operate so as to be compatible with other smart terminals. With such standards, your smart terminal could break and you could replace it with another made by a different vendor as long as both correctly implemented the VT100 standard--the the remote computer being interfaced to should not need to know the difference.

If you run a Command Window today on a Microsoft Windows Operating system, you get a virtual environment that is quite similar to what a smart terminal was. If you type incorrectly, you could hit the backspace key (and the previously typed character would disappear from the screen, because the keyboard had created a Backspace control code whenever you pressed, say, the Delete key). The backspace action all took place within the "terminal" by means of a local microprocessor. Only when a command had been entered correctly, and you then hit Enter, would the command be "interpreted" by the operating system (which in those days meant, sent serially to a central processing unit on a mainframe computer, rather than being handled by the local microprocessor in the terminal itself).
AlephZero
#21
Sep25-13, 01:32 PM
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Quote Quote by lpetrich View Post
As to present-day OS-less computers, I'd imagine that some small embedded ones are OS-less, but that's about it.
I don't think that is very likely. But the term "OS" has changed its meaning a lot over time. In a sense, 99% (or more) of what is in Windows or OSX isn't the "operating system" at all, it's just collection of applications and "cool stuff" that those nice people at Microsoft and Apple think you might find useful.

You can make a basic multi-tasking OS that will handle threads and processes, read and write a file system of disk, and interact with a keyboard and a network communications link in a very small amount of code - less than a megabyte. IMO it would be a dumb idea to try to build any 21st century computer system without starting from something like that as a solid foundation.
nsaspook
#22
Sep25-13, 10:33 PM
P: 599
Sometime a (RT)OS just gets in the way in embedded applications. Most real-time machine interaction level applications require very deterministic behaviours that can be difficult to achieve with a preemptive multi-tasking OS.

http://www.barrgroup.com/Embedded-Sy...emption-Perils
.Scott
#23
Sep25-13, 11:38 PM
P: 540
Early computers had "programmer panels" which allowed the operator to force data into memory and then cause those instructions to be executed. Those boot instructions were not entered in assembler, they were entered in machine language. Here are some examples:

Honeywell Series 200:
Push buttons would allow you to force one byte of memory at a time or to set a register. For example, setting memory location 0 to octal 15, then 1 to 0, then setting the a register A to 1, B to 2, and the Program Counter to 0, then hitting run would cause the instruction at 0 (15) to be executed. That instruction was a Move to A field word mark. But since B was one more than A, any word mark would be cleared in advance so all of memory would be cleared to the value in 1 (a zero).
You could also enter an IO device code and read. This would read one record from the device - for example, all the codes from one card in the card reader or the first record recorded on a tape. If that information was executable, you could then hit run and the program would run. Normally, that program woould immediately set up to read more of the program in from subsequent cards or tape record.

IBM 1620 - used in the Mercury space flight missions.
A typewriter-style keyboard would allow entry of data directly into memory. For example, something liek this was used to seek to cylinder zero on the disk drive, read in the first sector, and just to location 100 where that record had just been read: 34000320070636003200708490010000000000100

Honeywell 2000 series: Also used a typewriter-style device.

Early DECs: Mostly toggle switched that would allow words to be entered into sequential memory locations.

Data General NOVA: Similar to early DECs. The work length was 16-bits and a 16-word command string was needed to read in a paper tape program.
yungman
#24
Sep26-13, 12:31 AM
P: 3,883
When I started working in 78, I don't believe there is operating system to talk about, not even DOS. I remember different computer have their own way of booting up. I got a Radio Shack TRS80, I wrote basic programs in it. At work they used a system called CPM for a while. It was more primitive than DOS.

In a lot of sense, the primitive system is not necessary bad. We wrote assembly language programming and it ran fast and use very little memory. I am not trying to compare the complexity of today's software with those old stuffs, but the efficiency of the old programs seems to be lost as programming now uses so many modules calling here and everywhere that slows the program down.

the worst today is, people can't read and write in Hex!!! They have to use decimals. decimals has not bearing on the machine which uses binary. We were trained to think in Hex and it is so much more efficient once you pay the overhead of learning it.
Mark44
#25
Sep26-13, 01:15 AM
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Quote Quote by yungman View Post
When I started working in 78, I don't believe there is operating system to talk about, not even DOS.
At that time, most computers had an operating system, but this was just before personal computers really took off. My first experience with computers was in 1972, when I took a computer science class that used PL/C, a compact version of a language called PL/I (sold by, I believe, IBM).
We used keypunch machines to type each line of our programs, with one Hollerith (AKA IBM) card per line. We also had to type a few job control language (JCL) cards to go in front of and behind the cards in our PL/C deck.

Once the program was keypunched, we submitted it, and one of the computer guys would run a bunch of card sets through a card reader, which transcribed the code onto a tape reel. When enough programs were on the reel, somebody would "mount" the reel on the computer (some IBM model that I never saw), and run the programs.

There has to be an operating system that is able to load programs into memory and start running them.
Quote Quote by yungman View Post
I remember different computer have their own way of booting up. I got a Radio Shack TRS80, I wrote basic programs in it. At work they used a system called CPM for a while. It was more primitive than DOS.

In a lot of sense, the primitive system is not necessary bad. We wrote assembly language programming and it ran fast and use very little memory. I am not trying to compare the complexity of today's software with those old stuffs, but the efficiency of the old programs seems to be lost as programming now uses so many modules calling here and everywhere that slows the program down.

the worst today is, people can't read and write in Hex!!! They have to use decimals. decimals has not bearing on the machine which uses binary. We were trained to think in Hex and it is so much more efficient once you pay the overhead of learning it.
yungman
#26
Sep26-13, 01:47 AM
P: 3,883
Quote Quote by Mark44 View Post
At that time, most computers had an operating system, but this was just before personal computers really took off. My first experience with computers was in 1972, when I took a computer science class that used PL/C, a compact version of a language called PL/I (sold by, I believe, IBM).
We used keypunch machines to type each line of our programs, with one Hollerith (AKA IBM) card per line. We also had to type a few job control language (JCL) cards to go in front of and behind the cards in our PL/C deck.

Once the program was keypunched, we submitted it, and one of the computer guys would run a bunch of card sets through a card reader, which transcribed the code onto a tape reel. When enough programs were on the reel, somebody would "mount" the reel on the computer (some IBM model that I never saw), and run the programs.

There has to be an operating system that is able to load programs into memory and start running them.
I don't remember that clearly anymore, I think the TRS80 take basic directly. You type the basic and type run and it will.

In the CPM, you type in assembly language. If you type "Debug" and hit enter, it goes into debug mode and you type machine language code and run. It's been too long, I since totally left the field of programming. I avoid computer for years, totally skip the DOS. The first computer OS I learned since was Windows 95. So there is a big gap in my knowledge.

I remember the days of key cards. The TRS 80 was not much more than that, you just type on the screen with keyboard instead of the punching machine. It was quite natural to transition from key punch to those computers. The cpu was Z80 those days.
Chronos
#27
Sep26-13, 02:59 AM
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I used to stand in line at the computer lab at night to run my shoe box of punch cards on the IBM 360 at school. Get one lousy card out of sequence and ... God, I miss Fortran. Years later, I typed pages of hex to program my Apple IIe in what was then called 'machine language'. Mistype one lousy hex code out of 80 pages and ... you quickly learn the fine art of partial compilation.
SteamKing
#28
Sep26-13, 03:03 AM
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There were a whole slew of OSes in the 1970s, just not very many were PC oriented because the system resources were so meagre for these machines.

The large mainframe computers like IBM and Control Data had OSes which were time-share oriented. You would log onto the machine thru a terminal and usually submit your data to be run using a deck of cards or, if you were lucky, by submitting the card images stored in a data file. You got your results back either in another data file or by printer. If you had a really swish system, you might even get some plots.

The mini-computer makers, like DEC, had OSes similar to the mainframe makers, oriented for time-sharing. DEC had RSX-11 for their PDP-11 minis and when the VAX 780 machines came along, they developed VMS. All of these various OSes were proprietary.

For Intel 8080/Zilog Z80 machines, Digital Research's CP/M was the king-of-the-hill. There were compilers available for several different programming languages besides BASIC. Apple had Apple DOS, but this OS was no great shakes in the feature department.

When IBM was developing the PC, as the story is told, they came knocking on the door at Microsoft and at Digital Research, looking for an OS. CP/M was basically ready to go for the PC, since the 8086 processor could execute 8080 code. Microsoft had nothing on the shelf, just a few language products. It's still not clear why Digital Research could not strike a deal with IBM, but the cannier Bill Gates knew that a small company in Seattle had an operating system which worked on an 8086 processor. Gates was able to convince the IBM reps that he had an OS suitable for the new PC and was able to strike a deal. After the IBMers went back to NY, Gates quickly bought the source code and the rights to what became DOS for $50,000 from the cross-town computer shop, who were none the wiser as to Gates' ultimate purpose.
lpetrich
#29
Sep26-13, 05:32 AM
P: 518
Bill Gates's father was a corporate lawyer, so I think that his father helped him outwit IBM there. IBM got the rights to "PC-DOS", but he kept the rights to "MS-DOS". When the cloners got into business, Bill Gates knew what to sell them: MS-DOS.


As to OSes, there used to be lots of different proprietary ones without much compatibility between them. This changed with the rise of Unix in the 1980's, and most of the mainframe and minicomputer ones fell to the wayside. However, Unix vendors got into a big fight over standards in the late 1980's and early 1990's, and the "Unix wars" caused a lot of the trouble for the commercial Unix flavors. That made it easier for Microsoft to push Windows NT, and that enabled the rise of open-source Unix flavors like Linux. The biggest desktop Unix flavor is now not Linux but MacOS X, which is essentially an updated version of NextStep, Steve Jobs's would-be next big thing in the late 1980's. But Linux is now the biggest server OS, and Linux and OSX version iOS are now the biggest smartphone and tablet OSes.
jtbell
#30
Sep26-13, 08:34 AM
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Quote Quote by yungman View Post
When I started working in 78, I don't believe there is operating system to talk about, not even DOS.
When I started graduate school in physics in 1975, my department used a DEC PDP-10 computer with the TOPS-10 operating system. In 1978 we migrated to a DEC VAX 11/780 which used the VAX/VMS operating system.
BMW
#31
Oct2-13, 11:29 PM
P: 32
How did we do anything before technology made it easier? The answer is "the hard way."


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