[HN Gopher] Reverse-engineering the classic MK4116 16-kilobit DR...
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       Reverse-engineering the classic MK4116 16-kilobit DRAM chip (2020)
        
       Author : nickt
       Score  : 78 points
       Date   : 2023-09-24 14:04 UTC (8 hours ago)
        
 (HTM) web link (www.righto.com)
 (TXT) w3m dump (www.righto.com)
        
       | RetroTechie wrote:
       | Always interesting how much engineering went into a 'simple'
       | early chip like this. This was state-of-the-art once. :-)
       | 
       | Never liked these 4116s myself due to their multi-supply
       | voltages. Common cause of problems where used (like in the ZX
       | Spectrum as another poster pointed out).
       | 
       | And of course Ken Shirriff is brilliant as always!
        
         | kens wrote:
         | Thanks!
        
       | rwmj wrote:
       | The amazing thing (as Ken points out right at the end) is the
       | latest chips store 16 gigabits, about a million times larger, in
       | a similar area. So you can think of each of those 1979
       | transistors as now containing 10^6 2020's transistors! It's mind-
       | boggling. Also a million transistors is approximately an Intel
       | 80386 (actually it's a little bit more).
        
         | userbinator wrote:
         | _Also a million transistors is approximately an Intel 80386
         | (actually it 's a little bit more)._
         | 
         | 275k for a 386. 1.2M for a 486.
         | 
         | (I just noticed the Wikipedia article on the 386 is wrong ---
         | it gives both 275k and 855k, with the latter a citation to a
         | set of presentation slides that doesn't even contain the
         | numbers "855". Perhaps that's where the misinformation came
         | from? But I strongly remember the 275k number from early Intel
         | marketing material.)
        
           | kens wrote:
           | I looked into this: the 386SL has 855,000 transistors while
           | the other 386 versions have 275,000 transistors. I updated
           | the Wikipedia page, adding a reference to Intel's detailed
           | "Microprocessor Quick Reference Guide", which has transistor
           | counts for most of their chips. (I wish I had found this
           | guide long ago.)
           | https://www.intel.com/pressroom/kits/quickreffam.htm
        
             | userbinator wrote:
             | That page you found is not 100% either - it claims the 8088
             | has only 64k addressable memory.
        
       | johnklos wrote:
       | Neat! I remember feeling very, very fancy when I got my
       | Timex/Sinclair 16K RAM pack. It used 4116 chips. I was puzzled
       | why they'd have so many chips in the expansion instead of just
       | using static RAM, but back then everything was pricey. Compared
       | with the 2K of RAM the TS/1000 comes with, this was a huge amount
       | of memory :)
        
         | rwmj wrote:
         | And of course the ZX Spectrum main memory used only half of the
         | chips. Sinclair could buy faulty RAM chips very cheaply, they
         | binned them into "top half working" or "bottom half working",
         | then put either all tops or all bottoms into each Speccy and
         | set a solder point on the motherboard accordingly.
        
           | nickt wrote:
           | The Speccy used 4116s and 4164s (and later 4464s in the
           | Amstrad versions, except the "+2"). The 4116 was used for
           | lower RAM in 48k version, or all the RAM if you had a 16k
           | version. The 4164 was used for upper RAM, and they were the
           | ones that were binned for working upper and lower, and you
           | set a jumper to select the good half to use. In the 128k
           | "toastrack" and grey "+2" it used good versions of the 4164
           | for all its memory. A neat and typical Sinclair solution to
           | saving a few bob on each unit.
           | 
           | --edit to clarify the chips the +2 used
        
       | fred256 wrote:
       | Previous discussion:
       | https://news.ycombinator.com/item?id=25093933
        
       | mmastrac wrote:
       | This was a brilliant design. It had to balance cost in terms of
       | pins and dynamic refresh, with capacity and reliability.
       | 
       | It hit a sweet spot for everything that basically let this design
       | take over the world of early computing and it was easily
       | composable to larger memory sizes up to a point that was
       | sufficient for the time.
       | 
       | There's a pretty good reason this style of RAM is used on so many
       | machines of the time, in pretty much the same configuration, and
       | that you can pretty much swap RAM chips between machines of this
       | time.
        
       | ChrisArchitect wrote:
       | (2020)
        
         | ChrisArchitect wrote:
         | Discussion from back then:
         | https://news.ycombinator.com/item?id=25093933
        
         | kens wrote:
         | The MK4116 chip hasn't changed much since 2020, so hopefully
         | you will still find this article relevant :-)
        
       | [deleted]
        
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       (page generated 2023-09-24 23:00 UTC)