91–100 of 138 posts
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Everything is amazing and nobody's happy.
Identifying areas to improve is how we make progress
Why, the name of the website is 512pixels.net not 342pixels.net; he nailed the 512 dimension. :)
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The 68000 is 16 bit internally, and can access memory only 16 bits at a time, but the instruction set was designed with future iterations in mind, and most instructions can operate on 32 bit quantities - with a performance penalty. (Because in essence it has to do the work in 2 stages.) Whether this is enough to make it count as actually 32 bits is one for the philosophers.
No, this is very wrong. The 68000 is 32 bit internally and it has 32 bit registers: https://en.wikipedia.org/wiki/Motorola_68000 Externally it had 16 bits for databus and 24 bits for addresses. That is why we later got the 32 bit clean ROMs as Apple used the upper unused 8 address bits for flags.
And for more evidence, the Z80 is referred to as an 8-bit processor but has a 4-bit ALU.
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The 386SX was a similar story, and is normally thought of as basically 32bit. I think the perception difference may be down to timing; the 386SX came out _after_ the DX (with 32 bit data bus), so was thought of as a cheap 32bit chip, vs the 68000 which started off life with a 16bit data bus. (Fun fact: there was also the 68008, which was a 68k with an 8 bit bus!)
From memory, the primary advantage of the 386SX was the ability to use a cheaper 16-bit motherboard layout and components. The lack of a 32bit bus mattered less when most software was written with 286 compatibility in mind, and the ISA bus was only 16-bits wide, which limited the utility of the 32-bit bus for fast graphics transfers. The reduced 24-bit address bus was never a significant bottleneck during its commerc…
> the ISA bus was only 16-bits wide, which limited the utility of the 32-bit bus for fast graphics transfers.
Not only that, it was 8MHz to match the speed of the fastest IBM AT. VLB on a 486/33 or 66 ran at 33 MHz and was a godsend, 8x the bandwidth of 16-bit ISA.
The folklore link they reference: https://www.folklore.org/Five_Different_Macs.html The 1st edition of macworld, notably the first page is an advert for microsoft's products, multiplan spreadsheet, word, etc. https://archive.org/details/MacWorld_8404_April_1984_premier... The original floppy used on the mac was a single-sided 400KB disk. I imagine that was another set of trade-offs. https://folklore.org/Disk_Swappers…
Originally they planned on using custom 870K drives, but they were too unreliable so at the last minute they switched to the Sony 400K 3.5" disks
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But why 342 and tune the clock speed down instead of keeping the clock speed at 8MHz and having floor(8e6/2/6/60/32) = 347 lines? I suspect kmill is right: https://news.ycombinator.com/item?id=44110611 -- 512x342 is very close to 3:2 aspect ratio, whereas 347 would give you an awkward 1.476:1 aspect ratio.
That doesn't sound right. The tube the mac was displaying on was much closer to a TV-style 4:3 ratio anyway, there were significant blank spaces at the top and bottom. If I was placing bets, it was another hardware limitation. Maybe 342 put them right at some particular DRAM timing limit for the chips they were signing contracts for. Or maybe more likely, the ~21.5 kHz scan rate was a hard limit from the tube supplie…
https://nerdhut.de/2016/06/26/macintosh-classic-crt-1/
https://bobparadiso.com/wp-content/uploads/2014/09/timing.pn...
Beyond that, this article really wants to tell you how amazing that resolution was in 1984. Never mind that you could get an IBM XT clone with "budget" 720x348 monochrome Hercules graphics that year and earlier.
> “To minimize CRT flicker, Apple worked to achieve a vertical refresh rate of 60 Hz” … a limitation that many Macs, and even some iPhones, are still stuck with over 40 years later!
It's always surprising for me to see people regard 60 Hz CRT as "flicker-free", or "minimal flicker", etc. Whenever I saw a CRT running at 60 Hz, I'd be immediately be able to tell. Always used at minimum 75 Hz but preferably 85 Hz at home (early 2000s, Windows).
* The original VGA and thus most MS-DOS games ran at 70 Hz.
The article didn't nail down an exact reason. Here is my guess. The quote from Andy Hertzfeld suggests the limiting factor was the memory bandwidth not the memory volume: > The most important decision was admitting that the software would never fit into 64K of memory and going with a full 16-bit memory bus, requiring 16 RAM chips instead of 8. The extra memory bandwidth allowed him to double the display resolution, g…
Displays are still bandwidth killers today, we kept scaling them up with everything else. Today you might have a 4k 30bpp 144hz display and just keeping that fed takes 33Gbit/s purely for scanout, not even composing it.
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Displays are still bandwidth killers today, we kept scaling them up with everything else. Today you might have a 4k 30bpp 144hz display and just keeping that fed takes 33Gbit/s purely for scanout, not even composing it.
I have a 4k 60Hz monitor connected to my laptop over one USB-C cable for data and power, but because of bandwidth limitations my options are 4k30 and USB 3.x support or 4k60 and USB 2.0. I love the monitor, it's sharp and clear and almost kind of HDR a lot of the time, but the fact that it has a bunch of USB 3.0 ports that only get USB 2.0 speeds because I don't want choppy 30Hz gaming is just... weird.
