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Why did moving the mouse cursor cause Windows 95 to run more quickly?
487 votes

This is because of a flaw in the way Windows 95 generates events, and the fact that many applications are event driven. Windows 95 applications often use asynchronous I/O, that is they ask for some ...

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Why weren't bootable game disks ever common on the IBM PC?
94 votes

Bootable game disks do exist for the IBM PC. Conflict in Vietnam is an example of such a game. As can be seen on page 8 of the manual, the game boots directly without loading DOS first. The main ...

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Why does the original Donkey Kong update the screen in a curtain closing pattern?
Accepted answer
37 votes

Ken's answer is close but not quite right. On the real arcade hardware the signal sent to the CRT monitor is read directly from RAM as the electron beam scans over the screen. That means that ...

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Did arcade monitors have same pixel aspect ratio as TV sets?
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35 votes

CRTs don't have pixels, they don't work that way. Also, arcade monitors expose all the picture controls at the back so it is possible to adjust them quite extensively. Operators would have made sure ...

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What makes MOVEQ quicker than a normal MOVE in 68000 assembly?
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34 votes

The MOVE immediate instruction takes 8 cycles in byte and word modes. There are two memory reads, one for the instruction and one for the immediate value. The MOVEQ instruction encodes the immediate ...

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How did Elite on the NES work?
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28 votes

The cartridge contains extra RAM. The NES can use tiles in cartridge memory space, but that doesn't necessarily have to be ROM. With suitable RAM and memory mapping the cartridge can create a basic ...

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Why did 8-bit Basic use 40-bit floating point?
23 votes

Using a 32 bit signed mantissa and 8 bit unsigned exponent has one major advantage: You can re-use 32 bit integer math functions for operating on the mantissa. That re-use saves memory. It may even be ...

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What makes accurate emulation of old systems a difficult task?
23 votes

Almost all computer systems have multiple different devices operating in parallel. For example, the CPU is typically running parallel to the video generation hardware. This can be very difficult to ...

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Why does the Galaksija use SRAM instead of DRAM?
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23 votes

Many low cost computers of the era used SRAM instead of DRAM, including the ZX80, TRS-80 Model 100 and VIC-20. There were a few advantages. Much simpler to interface to, which is particularly ...

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Reason for gold lines on old ICs?
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23 votes

It's a ground wire. The way ICs were manufactured back then had the metal cover placed over the die as the last step, and grounding it helps protect the die from static shock and interference. If you ...

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Why the switch to "Mickey Mouse" (type C14) power cables?
Accepted answer
23 votes

It's because the C14 connector is rated for higher current (10A, up to 2400W), which means that it must be attached to a thicker and thus more expensive and less flexible cable. The cable can't be ...

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Why did Commodore 64 cartridge games disappear?
23 votes

In addition to RichF's answer, tapes were a lot cheaper than cartridges to manufacture. Tape duplication in the 80s was very low cost due to the high volumes involved, not least thanks to music ...

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Details of video memory access arbitration in Space Invaders
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22 votes

Space Invaders uses a simple display format where bytes are read from memory in order via an address counter, and shifted out via a shift register. Timing is controlled by discrete hardware. The ...

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What is a subpixel in Super Mario Bros, and how does it relate to wall clipping?
22 votes

In many 8 bit games the position of the player's sprite is stored as the pixel coordinates it rests on. For many games that is adequate, but it has some limitations. If the game only uses whole pixel ...

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Why did 1950s-60s computers have such wide words?
21 votes

Longer words mean more bits can be processed at once. An 8 bit processor can perform a 32 bit calculation, but it has to do it in 4 stages of 8 bits each. A 32 bit processor can do it in one stage. ...

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What is the most rudimentary input method a platform has ever been programmed in?
21 votes

On many early machines it was common to enter a minimal bootloader via switches on the front panel. The switches represented binary bits, with another switch to enter each word and advance the address ...

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What did the 'turbo' button actually do?
20 votes

The turbo button was implemented on machines with CPUs faster than the original IBM PCs. Some software relied on the CPU running at a certain speed to work properly, rather than using some external ...

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What causes that "organic fade to black" effect in classic video games?
18 votes

This effect happens when the luminosity curve of the image is adjusted like so: This is called gamma correction and is a fairly common feature of graphics processing software and GPUs. My research ...

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Back in 1984 I wrote some games for Spectrum - Will they still be playable?
16 votes

In regards to "is there a way to play my old games again?", there is a good chance that they are available online somewhere. You might start with the Internet Archive. Collectors and ...

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Why was the 6809 so expensive?
16 votes

It was just standard market positioning. The 6800 was still a current product and in use in many systems at the time, so they priced the 6809 as a more powerful alternative to both that and the Z80. ...

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How and why did Intel make the PCI bus "CPU Agnostic"?
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15 votes

Nobody has really covered the technical aspects of the PCI bus. Until then most busses had been mere extensions of the CPU's memory bus. Zorro was essentially an extension of the 68000 memory bus, S-...

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How did computers generate 'noise' sound files?
15 votes

Random noise patterns were usually generated by one of two common methods back in the 80s when simple waveform generating sound chips were popular. One technique is the Linear Feedback Shift Register ...

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How did Z80 multiprocessing work in the Namco Galaga hardware?
14 votes

The three CPUs were designated as follows: CPU 1 - Main game logic and control of the other two CPU 2 - Graphics and enemy movement CPU 3 - Sound The three CPUs communicate via shared RAM. CPU 2 and ...

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Why did common floppies never advance past 1.4 MB in size?
13 votes

Increasing capacity to a couple of megabytes just wasn't worthwhile. By the time drives became good enough to reliably do it at low cost we were already well into the era of CD-ROM. Floppy disk's ...

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Drilling 720Kb floppies to 'upgrade' them to 1440Kb?
Accepted answer
12 votes

Standard and double density disks used an iron oxide coating. High density floppies used a cobalt coating. The benefit of the cobalt coating was that bits could be placed closer together, allowing ...

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Why did Windows 95 crash the whole system but newer Windows only crashed programs?
11 votes

Although Windows 95 introduced support for 32 bit applications with memory protection, it was still somewhat reliant on MS DOS. For example, where native 32 bit drivers were not available, it used 16 ...

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Source Code Archival in early Game Developement
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11 votes

There is some anecdotal evidence that often there was no real source control or archival system in place, just ad-hoc backups. For example, a number of machines from 90s developers have been ...

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Why did the Apple IIe make a hideous noise if you inserted the disk upside down?
11 votes

The short answer is they did it to save money. They could have made the drive behave better when a disk is inserted upside down, but that would have required larger ROM chips to store the firmware or ...

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How did Satoru Iwata compress Pokemon GS to fit two regions on a single cartridge?
11 votes

The code for the decompression system has been decompiled and partially commented here. Essentially the compression used is a form of run-length encoding, with a few modifications to make it more ...

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How did people program for Consoles with multiple CPUs?
10 votes

There are two basic techniques: shared memory and dedicated communication ports. Shared memory simply allows both processors to access the same memory bus. There are some issues, as the bus has to be ...

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