[HN Gopher] Pentium on a 386 Motherboard
       ___________________________________________________________________
        
       Pentium on a 386 Motherboard
        
       Author : userbinator
       Score  : 95 points
       Date   : 2021-10-30 05:02 UTC (1 days ago)
        
 (HTM) web link (dependency-injection.com)
 (TXT) w3m dump (dependency-injection.com)
        
       | accrual wrote:
       | I tried searching but couldn't find an answer, is PODP == Pentium
       | Over Drive Processor? The top of the CPU shows PODP5V, so maybe
       | Pentium Over Drive Processor 5 Volt?
        
         | userbinator wrote:
         | Correct.
        
       | Agingcoder wrote:
       | This is great.
       | 
       | And I hadn't seen the name weitek in.. Well I can't remember!
        
       | bigmattystyles wrote:
       | Truly living up to the URL! Great stuff
        
       | krallja wrote:
       | With how easy that was, I'm surprised we didn't see more cursed
       | Pentiums in the 90s.
        
         | magicalhippo wrote:
         | I recall upgrading my 286 to a 468. Correction, it was one of
         | those Cyrix 486 clones on a 368 motherboard[1].
         | 
         | I bought the motherboard, CPU and RAM. Half the cost was the
         | 8MB of RAM. CPU was the next most expensive item.
         | 
         | Worked fairly well, but it was speed limited in certain cases
         | by the 386 motherboard/memory combo. Also not all
         | applications/games would run since they didn't properly detect
         | it as a proper 486.
         | 
         | [1]:
         | https://ancientelectronics.wordpress.com/tag/486-in-386-moth...
        
           | AnotherGoodName wrote:
           | There was even a "Make it 486" CPU for 286 motherboards so
           | you might have been correct. All the upgrades were terrible
           | though really and everyone knew it. Better to save up and get
           | a real 486 or Pentium.
        
         | [deleted]
        
         | don-code wrote:
         | It might not have been economically viable. The pace of
         | obsolescence at that point in time was so fast that it might
         | have been cheaper, over the course of two or three years, to
         | just buy a whole new system than to retrofit a Pentium to a 386
         | mainboard.
         | 
         | Consider what else happened in the 386 through Pentium
         | transition:
         | 
         | * The PCI bus became standard; your peripheral cards all needed
         | to change.
         | 
         | * SDRAM became standard; the memory bus became significantly
         | wider / faster, and you bottlenecked on RAM if you used older
         | mainboards.
         | 
         | * IDE, while it was already used for hard drives, was now used
         | for your CD drive too - you probably wanted a CD drive and not
         | a second floppy drive (different controller) in your machine,
         | which was harder if you only had a primary IDE bus.
        
       | tyingq wrote:
       | _" The MR BIOS on my board is quite confused and reports the CPU
       | to be 586SX, which I like"_
       | 
       | I think that's correct though. From what I can find, Intel
       | renamed 586 to 586SX after they released their MMX capable
       | Pentiums. So "non-MMX Pentium" is supposed to be 586SX. "MMX
       | Capable Pentium" is 586DX.
        
         | monocasa wrote:
         | Yeah, it's why it's Pentium has the 'pent' in it, being the
         | '5'86.. IIRC the trademark office told them they couldn't just
         | trademark a number so they did the next best thing.
        
           | _0ffh wrote:
           | Yep, at the time we were jokingly speculating if the next
           | generation would be called Hexium. =)
        
             | formerly_proven wrote:
             | I'm still disappointed that AM4 isn't PGA1337 and that they
             | never released an AMD Furion.
        
           | lostgame wrote:
           | That's fascinating to know! I'd personally had a 386 and 486
           | before I finally got a Pentium, and I never understood the
           | significance of the nomenclature. That's super neat!
        
       | SavantIdiot wrote:
       | I'm utterly baffled that this worked. Ignoring an entire border
       | of pins? Voltage levels from the chipset? Bios recognition? IO
       | timing diagrams?
       | 
       | I kinda don't believe this, but I'm too lazy to look up old
       | datasheets.
        
       | giuseppeciuni wrote:
       | Great job!!! And even funny to do I suppose!
        
       | morsch wrote:
       | This led me to this gem on Wikipedia: _The i487SX (P23N) was
       | marketed as a floating-point unit coprocessor for Intel i486SX
       | machines. It actually contained a full-blown i486DX
       | implementation. When installed into an i486SX system, the i487
       | disabled the main CPU and took over all CPU operations. The i487
       | took measures to detect the presence of an i486SX and would not
       | function without the original CPU in place._
       | 
       | https://en.m.wikipedia.org/wiki/X87#80487
        
         | SavantIdiot wrote:
         | There was also 486 in a 386 socket called Sidewinder at Intel,
         | but it never shipped. It had an ASIC on the back of the
         | package. There's no record of this anywhere on Google.
        
       ___________________________________________________________________
       (page generated 2021-10-31 23:00 UTC)