New answers tagged ibm-pc
2
One nuance to the Pentium 133 is that it used precharge, domino logic (please correct me if I am wrong; I recall this from an Intel presentation). This logic requires a minimum speed to operate. This minimum speed is one reason that you could not have a legacy "turbo" switch change the speed, because it would violate the logic timing, which you could ...
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Chromatix answer already perfectly nails the technical background. Especially the reference to classic typewriter mechanics, predating any TTY or terminal, were the symbol used quite closely follows the hand movement when isueing a new line.
Historically it may be interesting to look at the development. The combined function as a single key was only ...
47
Even though the CR usually goes before the LF in ASCII text, most printer mechanisms actually perform the LF before, or during, the CR. So the shape of the arrow is actually accurate.
This is even true of mechanical typewriters, in which the carriage is returned through a physical lever which, before enough force is transmitted through it to move the ...
1
386 and some early 486 board had still a Turbo button that slowed down the CPU speed.
I had a Vobis 386 computer that had an 8 MHz/25 MHz 386.
From what I recall in the manual was explained that was for reading copy protected floppies or software that didn't work at the higher speed.
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IIRC at the time cheaper cases were sold as XT/AT cases and in addition to taking AT motherboards had the mounting holes and turbo switches for old XT motherboards years after people stopped buying them new, while newer AT only cases were slightly more premium. Also some newer motherboards would still have a jumper to accept a turbo switch and would slow ...
19
The purpose of the switch is to support CPUs that can work at different clock frequencies.
However, the presence of a turbo switch and a frequency display on a case, do not necessarily imply that the CPU can actually work at different clock frequencies, because the case is a generic case which has not been designed for one specific CPU.
Background
I ...
29
Your premise that the point of the Turbo button was originally to slow down the computer to be timing compatible to an IBM PC/XT is correct. There was demand for that function, because a some of software, mostly games, were not synchronized to any timing source, but just scaled with the CPU frequency. some examples I encountered at that time are:
Bugs, 1982
...
6
I thought the whole point of the turbo switch was to enable compatibility with games that expected 4.77MHz. What was the purpose of the slow/fast turbo setting on PCs whose CPUs could not slow down to 4.77MHz?
The turbo switch lost that purpose much earlier. It did that job on 8088 PC compatible machines runing at slightly higher clock speeds (in the 8-10 ...
9
I thought the whole point of the turbo switch was to enable compatibility with games that expected 4.77MHz.
A very similar question was already asked here.
One answer was that the "Turbo" button was often used for other purposes (such as switching an additional fan on or off) by users whose motherboards did not support the "Turbo" button.
When there were ...
13
TL;DR;
Looking at the linked board manual reveals that it doesn't support any 'turbo' switch. So this is simply a case having it, while there is no purpose - maybe except for the fun of having a button that switches the illuminated segments :)
It might be safe to assume that the board has been updated or the case been used regardless. After all, why throw ...
31
Worshipping at the altar of color clock
Back in that day, everything was built around the NTSC color clock frequency of 3.579545 MHz. Everything from the Atari VCS to the C64 made ample use of it, because some iteration of your product would inevitably need to talk to a commodity color NTSC display operating at that frequency.
This will come up; so FYI ...
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For many kinds of parts, there's a substantial gap between specified maximum/minimum timings and typical timings. The 8088 specification requires that the clock be high for a minimum of 69 ns every cycle and low for a minimum of 118 ns. Dividing a 14.3818 Mhz clock by three yields a high time of 69.5 ns and a low time of 139.1 ns, satisfying both ...
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Quartz used in colour TVs such as 3.579545MHz or 14.31818MHz used to be much cheaper than other frequencies.
It was important for home computers and game consoles (8/16 bits), which used the same quartz for video and the CPU, keeping everything synchronous.
It was far less siginificant for rather expensive computers such as IBM PC which didn't need to ...
0
The other answers mention PS/2 and MCA but don't quite bring out the political dimension.
The history behind it is that when IBM came fairly late to the 16-bit PC market, populated with a wide variety of hardware architectures (all loosely based around the 8086, and unified by all being compatible with Digital Research CPM/86) they did so with an unusually ...
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I would suggest that choosing an industry group’s standard rather than that of a single company is obviously preferable to anyone not in that single company.
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I think that this was part of the larger trend of IBM losing the leadership of the “PC”, especially after the PS/2 and the MCA debacle (although the PS/2 line did introduce many new features which became de facto PC standards).
Looking at graphics specifically, after the VGA, IBM developed the 8514/A and then the XGA. For most consumers these had several ...
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VGA was introduced in 1987 with IBM's PS/2 line. NEC and VESA developed SuperVGA in 1988, but at the time it used the old and slow 8/16-bit ISA bus.
Improving video performance was a top priority at NEC to help sell its
high-end displays as well as its own PC systems. By 1991, video
performance had become a real bottleneck in most PC systems. (316)
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