[HN Gopher] An unusual 7400-series chip implemented with a gate ...
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       An unusual 7400-series chip implemented with a gate array
        
       Author : codezero
       Score  : 77 points
       Date   : 2024-03-30 17:33 UTC (5 hours ago)
        
 (HTM) web link (www.righto.com)
 (TXT) w3m dump (www.righto.com)
        
       | formerly_proven wrote:
       | Sort of the opposite of a "we have 7400 series at home" joke.
        
       | kens wrote:
       | Author here if there are any questions...
        
         | cosmolev wrote:
         | Why have you wasted 80% of the die?
        
           | kens wrote:
           | I'm not sure what you're asking. IDT used the same gate array
           | for numerous 7400-series products. As a result, simple chips
           | would waste most of the die, while complex chips would use
           | most of it. The tradeoff is that using a gate array saves
           | design costs, although each chip is more expensive to
           | manufacture due to the wasted silicon. Since IDT was selling
           | into low volume, price-insensitive markets (military), the
           | tradeoff was worthwhile.
        
           | cdcarter wrote:
           | kens is the author of the write up, not the designer of the
           | chip.
        
       | francescovv wrote:
       | > transistors in an orderly matrix (...) forming scattered
       | circuits connected by thin metal wires.
       | 
       | That's [ULA], isn't it? This tech was also known as "Gate Array",
       | before FPGA came along.
       | 
       | [ULA] https://en.wikipedia.org/wiki/Uncommitted_logic_array
        
         | kens wrote:
         | Yes, a ULA is another name for a gate array. A while ago I
         | bought an 8086 chip on eBay that turned out to be a random ULA
         | chip that was re-labeled:
         | https://www.righto.com/2020/08/inside-counterfeit-8086-proce...
        
           | hyperman1 wrote:
           | From that article:                 The book The ZX Spectrum
           | ULA: How to design a microcomputer discusses [...]
           | 
           | I had no idea such a book even existed. Now I am really
           | curious about what other hidden gems exist on your bookshelf.
        
       | hyperman1 wrote:
       | Funny to see this appear online today. I was discussing the real
       | nand2tetris computer built from 74 ICs yesterday with my 8 year
       | old son yesterday:
       | 
       | https://hackaday.io/project/185131-the-hack-computer-from-na...
       | 
       | and now this pops up.
       | 
       | I'm thinking of buying a bunch of 74xx ICs and buttons and
       | led+resistors somewhere and let him mess with them. It's stone
       | age digital tech according to current norms, but I'd rather see
       | him do it with physical components than behind a screen.
        
         | pulvinar wrote:
         | That's what my dad did. I remember it as confusing, the parts
         | being marked like SN7424 7411 with one of those numbers being
         | the date code.
        
         | Spastche wrote:
         | do it. you can use them all for basic synth building too.
         | sequencers and square waves are stupidly easy to build
        
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