[HN Gopher] Oya, I've heard of mega-ROMs
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       Oya, I've heard of mega-ROMs
        
       Author : zdw
       Score  : 57 points
       Date   : 2024-09-03 16:50 UTC (3 days ago)
        
 (HTM) web link (www.leadedsolder.com)
 (TXT) w3m dump (www.leadedsolder.com)
        
       | dietrichepp wrote:
       | > Normally, I would expect floating address pins to be completely
       | random, but this was very consistent.
       | 
       | I think "random" assumes some kind of perfect conditions. There
       | will be leakage current to ground, leakage current from Vcc, and
       | the actual threshold between high and low for the input will be
       | some particular value.
       | 
       | Just a quick look at the data sheets for the SN54LS670 from TI,
       | and I see that the output pin leakage current is rated at no more
       | than 20 uA. That's worst-case, but if you apply Ohm's law and
       | plug in 3.3 V, you get something on the order of 160 kO output
       | impedance. I have a limited understanding of electronics and I'm
       | sure I'm missing something, but I'd expect a lot of the output
       | pins to settle on a reasonably stable voltage when they are
       | turned off. Maybe natural variations in geometry or chemistry
       | will push some pins higher and other pins lower.
       | 
       | You can run an entire CPU core with less than 20 uA current these
       | days, just to give it a sense of scale.
        
         | jmann99999 wrote:
         | The detail and knowledge shared in these three paragraphs are
         | why I love Hacker News.
        
       | jbverschoor wrote:
       | The Maze of Galious is such an underrated game in terms of IP.
       | 
       | I had the pleasure of attending MSXGOTO40 last december.
       | 
       | Great explanation what megarom actually means, I never knew
        
       | ibizaman wrote:
       | > [About buying a used cartridge] In retrospect, after all this
       | adventure, that doesn't seem like much, but "spending fifty bucks
       | instead of learning something" is not the name of this blog.
       | 
       | Absolutely love this quote.
        
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       (page generated 2024-09-06 23:00 UTC)