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TL;DR: It was IBM's idea.
IBM never intended to buy any of the software they acquired for the PC - and MS never intended to supply any OS beside Xenix.
But MS (Paul Allen) soon recognized the potential business and acted accordingly.
The Long Read
IBM had no interest whatsoever in setting up a basic software development for the PC. The strategy was to ...
51
TL;DR;
Punch card code is not binary but a collection of n out of m encodings.
Long Story
Yes, really a long story, so I'll only cover the main line from Hollerith to EBCDIC. There are many sidelines for special equipment, situations and as used by different manufacturers. Some covering up to 7 holes but all mostly compatible in the basic Numeric/Alpha ...
46
Very simple: Because there was room for an address and it improves performance a lot. Or as the manual puts it:
It is important, however, for the programmer to realize that the simplest method of programming (using sequential drum location for succeeding instructions) causes the machine to waste a large amount of time waiting and searching.
To start with,...
41
Specifically concerning EISPACK. what happened was that James Hardy "Jim" Wilkinson in the UK (whose career as an applied mathematician started with practical ballistic modelling in WWII, working with Turing and other computing pioneers, and continued for the rest of his life at the UK National Physical Laboratory, not in some academic ivory tower) ...
34
Classic IBM 224 Dictating Unit using a magnabelt, often called a Dictaphone, although that wasa trademark of a different company. Introduced in 1966 and sold in high volume and worldwide, way into the 1970s.
Seen here in action.
So while being from IBM, it's in no way computer related. They are still a common find. Only complete setups, including the ...
34
Yes. There were CP/CMS and VM/370 - true multiuser operating systems running on the mainframe with individual users logged in. AFAIK it was mainly used for software developers (to develop IBM mainframe software).
I had the pleasure working on VM/370 once. Not what you'd call an ideal development environment. You got storage allocated to you: A certain ...
31
Uppercase text only needs six bits per character.
The fundamental mistake that you are making is assuming that punch codes were binary numbers.
They were not.
The encodings were patterns, combinations of of zero, one, two, or three holes.
This is a reference card in IBM 5081 format:
The row numbering was somewhat odd, for historical reasons: 12, 11, 0, 1, ...
30
Although you have many correct answers describing the nature of the coding used in punched cards, no one has touched on the mechanical properties of the cards. Regular users of punched cards in the past would be familiar with this issue, as getting cards through the mechanics of a fast card reader regularly and repeatedly was a major issue at the time.
If a ...
27
The cited source from the question is the source for the English Wikipedia page as well, that claims that there are only very few known viruses for that system.
But the low amount of viruses seems to be much bigger.
Not two, but at least five viruses are well known. That's more than double.
Arelocs also known as Aep is one of a few viruses for IBM's OS/2 ...
27
There is a clue in the name - BCD stands for "binary-coded decimal", where 4 bits are used to represent 1 decimal digit (0-9). The hexadecimal values A-F are not used in BCD.
EBCDIC is an extended version of BCDIC, and it shifts BCDIC alphanumerics, and inserts characters in some of the non-decimal positions. But there's a simple relationship to ease ...
27
The History section of the Wikipedia Virtual Memory page seems to have the details of this:
The concept of virtual memory was first developed by German physicist Fritz-Rudolf Güntsch at the Technische Universität Berlin in 1956 in his doctoral thesis, Logical Design of a Digital Computer with Multiple Asynchronous Rotating Drums and Automatic High Speed ...
26
I have not found a reference, but here's a search for OS/2 on Trend Micro's virus encyclopedia. That finds 30 entries, some of which are actual OS/2 viruses, and some of which are interesting OS/2 security vulnerabilities.
It looks as if there are five OS/2 viruses in that list, but it's unknown if any of them are multiple names for the same virus, or ...
23
My wife began work at MSFT in the downtown Bellevue office in late 1981 (approx employee #90-ish) just a couple weeks before the company's move to the highway 520 building next to the Burger King on everyone's speed-dial. She worked with Jeff Raikes and Trisha in CorpComm. Though not software developers, CorpComm people interfaced with many departments and ...
20
As pointed out by Jon Custer, part of the reason is due to the input at the time being punch cards. If holes were close together there was a risk of the card being unreadable or ripping.
In addition, this punch card from the Wikipedia article helps explain why both uppercase and lowercase end at 0x_9. The punch card only goes from 0 to 9. I don't know how A ...
20
TL;DR:
Which components or facilities were the biggest obstacle to porting typical COBOL applications?
Simply that there were not many applications that made sense to be ported to (desktop) micros. If at all, downward migration of whole applications was toward /3x systems and ultimately AS400. Which was well supported and rather painless.
<RANT>
...
20
IBM mainframes are still around (IBM Z). Linux has been available for IBM Z hardware and its predecessor, System/390, for 20 years, and z/OS is itself a certified UNIX through the z/OS UNIX System Services. Which is to say that IBM mainframes have been run in UNIX-like multi-user fashion for two decades by running UNIX.
Apart from that, z/OS and its ...
19
It can be found in implementations of zfs such as OpenZFS, inherited from the Solaris Kernel Memory C header file:
https://github.com/openzfs/openzfs/blob/master/usr/src/uts/common/sys/kmem_impl.h line 80
#define KMEM_FREE_PATTERN 0xdeadbeefdeadbeefULL
Quote from the magic number wiki page:
"Dead beef", Famously used on IBM systems such as the RS/...
19
IBM started using ASCII before 1970; the 2260 terminal, released in 1964, used the unpublished (but ratified) 1965 version of the ASA X3.4 standard.
IBM mainframes still use EBCDIC, so I don’t think their popularity had much bearing on the popularity of ASCII (but other encodings’ popularity influenced IBM mainframes: their instruction set includes ...
19
TL;DR:
ASCII was never intended for processing, just as an interface standard for data exchange (hence the name American Standard Code for Information Interchange)
IBM never switched, it still uses EBCDIC within mainframes and ASCII for communication.
IBM was a major proponent for ASCII, but not the sole force, and especially not international.
ASCII soared ...
18
One alternative to the trackpoint was a trackball, either below the screen (as in the Macintosh Portable), or next to the screen (as in the Compaq LTE Lite). When the trackball was next to the screen the mouse buttons were typically on the back (you would roll the ball with your thumb, and press the buttons on the back of the screen using index and middle ...
18
What is the purpose of the yellow wired panels
It's the backplane, simply the wiring of the machine.
on the IBM 360 Model 20?
Not just there, but next to every mainframe was made that way. Depending on planned (and ordered) production run some would get printed boards, but usually all wiring was done as wire-wrap. The -20 was sold in quite high numbers ...
17
it says the original 8inch floppy disk from 1971 could store 80kb of data equivalent to that of 3000 punched cards
Given, the text is a bit misleading, as it mixes up firsts. While it is true that the first Floppy, used in a product, in 1971, had a storage of 80 KiB (exactly 79,75), it was neither used as generic storage media not available for user storage ...
17
Wikipedia, unsurprisingly, gives incomplete information. A number of important new technologies were developed as part of the five-year R&D of SABRE, including a disk drive capable of storing that many reservations, a new transaction-processing system, a frequency-modulation system to send data over the phone lines, and a new model of terminal, pictured ...
16
In a 100% compatible PC, NMI is used only to communicate unrecoverable errors — normally a RAM parity failure, but possibly something else, which should reveal itself via one of the system control ports, specifically you should check:
Port A:
b4: watchdog timer status;
Port B:
b6: channel check failure (i.e. a bus failure, likely a peripheral device);
b7:...
16
Another one to mention is MTS which was first released in 1967, last release in 1988. It was in use at Rensselaer Polytechnic Institute from 1976 to 1999, of which I took part during the early 80s. In 1984 they were running it on Sybil, a dual processor IBM 3081D; slightly before that it ran on Myron, which I think was a 3070 but I'm not sure.
There were a ...
16
I don't agree with the answer you read on quora. DEC did have a partner relationship with a certain kind of customer, namely engineering and science labs. Ken Olsen and the engineering staff at DEC all understood how scientists and engineers think and what they want.
But this was without any marketing specialists to act as liaisons.
Sometime in the 1970s, ...
15
I found the explanation in chapters 23 and 20 of Mackenzie, Charles E, Coded Character Sets, History and Development (Addison-Wesley, 1980), which was linked in a footnote to Wikipedia's ASCII article.
In the early 1960s, 7-bit ASCII was being standardized as an communication format (the last I in the name comes from "interchange"), but this does not ...
15
The 80286 has a maximum power dissipation of 3.3W and an operating range of up to 70°C. Unless you want to operate near that point, no heat sink is needed. The ICs surface is alreaady way too large.
Beyond that it falls into the same class as iluminated cables and coloured ribbons. Not needed but doesn't do harm either (if done properly).
From a historic ...
14
The IBM5291 is one of the IBM5250 series of terminals. It provides a user interface to an IBM minicomputer.
The interface will be by Synchronous Data Link Control (SDLC). The hardware being paired co-ax wire system. This enabled a number of these terminals to be daisy chained to a single port on the host minicomputer.
There are a number of modern ...
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