By Soulskill from Slashdot's causing-frustration-is-a-valid-design-strategy department
An anonymous reader writes "The Z-80 microprocessor has been around since 1976, and it was used in many computers at the beginning of the PC revolution. (For example, the TRS-80, Commodore 128, and ZX Spectrum.) Ken Shirriff has been working on reverse engineering the Z-80, and one of the things he noticed is that the data pins coming out of the chip are in seemingly random order: 4, 3, 5, 6, 2, 7, 0, 1. (And a +5V pin is stuck in the middle.) After careful study, he's come up with an explanation for this seemingly odd design. "The motivation behind splitting the data bus is to allow the chip to perform activities in parallel. For instance an instruction can be read from the data pins into the instruction logic at the same time that data is being copied between the ALU and registers.
[B]ecause the Z-80 splits the data bus into multiple segments, only four data lines run to the lower right corner of the chip. And because the Z-80 was very tight for space, running additional lines would be undesirable. Next, the BIT instructions use instruction bits 3, 4, and 5 to select a particular bit. This was motivated by the instruction structure the Z-80 inherited from the 8080. Finally, the Z-80's ALU requires direct access to instruction bits 3, 4, and 5 to select the particular data bit. Putting these factors together, data pins 3, 4, and 5 are constrained to be in the lower right corner of the chip next to the ALU. This forces the data pins to be out of sequence, and that's why the Z-80 has out-of-order data pins."Read Replies (0)
By timothy from Slashdot's everyone-has-their-reasons department
An anonymous reader writes "Open source operating systems vulnerable to the Shellshock bug have already pushed two patches to fix the vulnerability, but Apple has yet to issue one for Mac OS X. Ars Technica speculates that licensing issues may be giving Apple pause: "[T]he current [bash] version is released under the GNU Public License version 3 (GPLv3). Apple has avoided bundling GPLv3-licensed software because of its stricter license terms....Apple executives may feel they have to have their own developers make modifications to the bash code.""
It's also worth noting that there are still flaws with the patches issued so far
. Meanwhile, Fedora Magazine has published an easy-to-follow description of how Shellshock actually works
. The Free Software Foundation has also issued a statement about Shellshock
.Read Replies (0)
By timothy from Slashdot's more-faster-cheaper department
An anonymous reader writes "A research team from the University of Texas and a German nanotechnology company have published a paper which describes a major milestone for the future of graphene-based computing – the reliable production of wafer-scale graphene measuring between 100 and 300mm, suitable at last for integration with 'traditional' materials in computing. The research team was able to manufacture 25,000 graphene field-effect transistors from lab-produced graphene film on a polycrystalline copper base. Team research leader Deji Akinwande said: 'Our process is based on the scalable concept of growing graphene on copper-coated silicon substrates...Once we had developed a suitable method for growing high-quality graphene with negligible numbers of defects in small sample sizes, it was relatively straightforward for us to scale up.'"
(Original, paywalled paper
is at ACS Nano
.)Read Replies (0)
By timothy from Slashdot's isn't-that-what-the-white-house-calls-it? department
An anonymous reader writes A new interview published this week looks at the creation of Infinite Crisis, one of the slew of Dota 2/League of Legends team multiplayer competitors currently under development. What makes this one stand out however is not only its use of DC Comics heroes like Batman and Wonder Woman, but the experience of the studio behind it, Turbine, in massively multiplayer online games and punishing abusive and toxic players, something League of Legends developer Riot has serious struggles with. Turbine was the studio behind the popular Asheron's Call, and is applying many of th same policing techniques it used in RPGs to the growing MOBA genre. Of course, they still have troubles with the inevitable: balancing Superman as a playable character. it's a challenge, Kerr admits, especially when you're having to nerf the Man of Steel as a result. "Yes, we redid Superman three times, because, and I know this is going to be a surprise, he was super overpowered," says Infinite Crisis creative director Cardell Kerr.Read Replies (0)
By Soulskill from Slashdot's time-keeps-on-slipping-into-the-future department
You might want to go back to Video 1
before watching this one (or reading the transcript). This video is the second part of our recording of a panel discussion at the recent science fiction convention in Detroit. Panelists include writer and forensic science expert Jen Haeger
; professor and generally fascinating guy Brian Gray
; and expert in Aeronautical Management and 20-year veteran of the Air Force Douglas Johnson
. In this video, they continue running down a list of science fiction predictions, both successful and unsuccessful, and evaluating how realistic or far-fetched each now seems. (Alternate Video Link
)Read Replies (0)