55
votes
Accepted
Did IBM encourage Bill Gates to retain the rights over PC-DOS?
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 ...
- 213k
53
votes
Accepted
What did code on punch cards do with the other six bits per column?
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 ...
- 213k
47
votes
Accepted
Why does an instruction include the address of the next instruction on the IBM 650?
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 ...
- 213k
45
votes
Accepted
Why was IBM's Scientific Subroutine Package superseded?
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, ...
- 6,646
37
votes
Accepted
Were any IBM mainframes ever run multiuser?
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 ...
- 6,119
34
votes
Accepted
What is the function of this strange IBM apparatus?
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 ...
- 213k
32
votes
What did code on punch cards do with the other six bits per column?
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, ...
- 2,278
31
votes
What did code on punch cards do with the other six bits per column?
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 ...
- 5,597
30
votes
Accepted
What date is 74029 on an IBM Mainframe?
TL;DR: DATE=74029 reads as: Year (19)74, Day 029 (Jan 29th),
It's an Ordinal Date in truncated form, expressed in terms of 2 digit year and 3 digit day of the year.
Does anyone know when was it ...
- 213k
30
votes
Accepted
Did the IBM ServiceFree really reach 80 MIPS in 1975?
This seems to be a mangled account of the IBM 801. The project was led by John Cocke. This started as a project for a computerised telephone switch, which needed a lot of instructions per second, but ...
- 12.4k
29
votes
Was there a clearly identifiable "first computer" to use or demonstrate the use of virtual memory?
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 ...
- 24.6k
28
votes
Accepted
How many OS/2 viruses were there?
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 ...
- 1,586
28
votes
Accepted
Why wasn't EBCDIC designed with contiguous alphanumeric characters?
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 ...
- 1,626
27
votes
How many OS/2 viruses were there?
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 ...
- 12.4k
25
votes
Accepted
What was the most critical supporting software for COBOL on IBM mainframes?
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. ...
- 213k
24
votes
How widely was 0xDEADBEEF used as a placeholder, invalid value?
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 ...
- 928
23
votes
Did IBM encourage Bill Gates to retain the rights over PC-DOS?
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 ...
- 347
23
votes
Did the IBM ServiceFree really reach 80 MIPS in 1975?
John Dallman already showed the 801 being the most likely one referred to. The 801 was indeed the ground breaking work Mr. Cocke was later recognized for. In addition it might be helpful to check the ...
- 213k
21
votes
Why wasn't EBCDIC designed with contiguous alphanumeric characters?
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, ...
- 663
21
votes
Were any IBM mainframes ever run multiuser?
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 ...
- 9,820
21
votes
Accepted
Did the IBM 1401 have much better code density than the 360?
TL;DR: No.
/360 code was usually way more compact for the same task than 1401 code. Partly due to shorter instructions (2..6 Bytes vs 1..8 Char
(*1)), partly due to a more capable ISA (use of ...
- 213k
21
votes
Was bootloading from punch cards possible on System/370 machines?
Sorry for the narrative here, but it answers the OP's question directly by personal experience. The text is too long for a comment.
"Was bootloading from punch cards possible on System/370 ...
- 367
20
votes
Accepted
What is the purpose of the yellow wired panels on the IBM 360 Model 20?
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. ...
- 213k
20
votes
Did the IBM PC use the 8088's NMI line?
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 ...
- 35.9k
20
votes
Accepted
When did IBM start to use ASCII?
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 ...
- 213k
20
votes
Were any IBM mainframes ever run multiuser?
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 ...
- 301
20
votes
Accepted
What programming languages were most commonly used on the AS/400 in the 90s?
IBM i is actually the name of an operating system rather than the hardware. So, it is the successor to OS/400 rather than AS/400. The current hardware is IBM Power Systems. These can also run AIX ...
- 2,014
20
votes
Accepted
Was bootloading from punch cards possible on System/370 machines?
TL;DR: Yes, a /360 (*1) can boot from any device connected to a channel.
A /360 can boot from any device able to answer to a basic read command. Whatever is delivered will be executed. There is no '...
- 213k
19
votes
When did IBM start to use ASCII?
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 ...
- 118k
Only top scored, non community-wiki answers of a minimum length are eligible