Two Stop Bits | thought_alarm's comments

thought_alarm 3 days ago | parent | on: Why the Original Macintosh Had a Screen Resolution...
512 pixels across is the sane and obvious choice for a 9" screen. It's 64 bytes/32 words across, which is a nice and even number. The next step up would be 640 pixels (40 words across), but it's probably not worth the memory tradeoff.
The Apple IIc shipped with the same 9" monochrome monitor and can do 560 pixels across (40 words, 14-pixels per word for historical reasons). It's hard to imagine shrinking the pixels much further on that screen.
The Apple IIgs can draw 640 pixels across in the same width that the Apple II draws 280 pixels. I suppose one could connect an Apple IIc monitor to the IIgs and experiment with monochrome 640x200 graphics to see how the smaller pixels look. (I own both, so maybe I'll try it out).
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- ddingus 1 day ago
  Yes, the decision to match the GS screen width to the Apple 2c was a poor one when it comes to NTSC composite video.
  The result was the GS pixel clock does not align with the NTSC colorburst period. It made artifact color useless, and that was sad because the GS could have done amazing graphics on an ordinary TV.
  But, that aside, the overdriving of the color signal meant most users suffered through crappy video, or ran the machine monochrome, or had to buy the Apple monitor.
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thought_alarm 46 days ago | parent | on: The UCSD p-System, Apple Pascal, and a dream of cr...
All versions of Apple Pascal use 16-bit pointers, so data was always limited to a 64 KB address space. On the 128K Apple II, p-code was located in aux memory, and data was located in main memory.
Apple III Pascal had similar limitations, with separate 64K address spaces for p-code and data. On machines with more than 128 KB of RAM, there were assembly routines available for allocating additional memory and swapping data memory.
thought_alarm 316 days ago | parent | on: That Time Apple Told Apple III Customers to Drop T...
Unfortunately, very little of this article is accurate.
The Apple III's RAM is located on a separate board mounted above the motherboard using a custom connector. The initial RAM connector had a design flaw that wasn't caught during testing and ended up shipping. The flaw caused the machine to intermittently lose connection to its RAM, and without RAM the machine obviously doesn't run. Jostling things around restores the connection to RAM and get things working again.
Apple redesigned the RAM connector and then recalled all of the initial machines through their authorized dealer network. Every motherboard was replaced, regardless of whether it exhibited problems or not. Apple continued to sell the Apple III for four years using the same aluminum heat sink for its entire run. During that run it was as reliable as any other machine on the market.
The Apple III never had an overheating problem. It did not contain chips that were magically able to unseat and reseat themselves. These were all just theories that people invented to try to explain the behavior they were seeing. The theories were complete fiction, and are laughably preposterous in retrospect. And yet, the theories continue to be repeated as fact 40+ years later.
The Apple III was an important chapter in Apple's history not because it was a dud, but because of the way it developed an untrue reputation for poor reliability that it was never able to shake in the four years it was manufactured and sold.
The "Drop Three Inches" podcast is a great listen if you want to more about the Apple III. http://drop-iii-inches.com