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Thread: WTB 4116 DRAMs

  1. #1

    Default WTB 4116 DRAMs

    Well, I did speak too soon. No sooner had I got my !00 box booted, but the RAM board did something and the DRAM chips are partially toasted.

    Has anyone got any spare they would like to dispose of? Payment via PayPal, shipping to UK.

  2. #2
    Join Date
    Oct 2016
    Location
    Burnley, UK
    Posts
    253

    Default

    I just bought 15 2114 SRAM ICs off Jameco - came to about 15 The shipping was about the same.

    They seem to have 4116s here:

    https://www.jameco.com/z/4116-15-Maj...-16_41339.html

    The ICs were a known make - I was able to test them with my ABI chip tester.

    The slightly upsetting thing was that Jameco use Parcelforce to get the package from Heathrow to your doorstep. Parcelforce seem to charge their own small fee and mix in the import taxes which you pay at the sorting/post office. I probably ended up paying another 15.

    If you can find the same ICs with didgikey for example, all the taxes are included in the checkout price and the postage is free if your order is over 30 or so.

  3. #3
    Join Date
    Oct 2016
    Location
    Burnley, UK
    Posts
    253

    Default

    May be worth replacing the regulators on the boards? Is that what shorted and fried the RAM?

    Quote Originally Posted by JonB View Post
    Well, I did speak too soon. No sooner had I got my !00 box booted, but the RAM board did something and the

    DRAM chips are partially toasted.

    Has anyone got any spare they would like to dispose of? Payment via PayPal, shipping to UK.

  4. #4

    Default

    Quote Originally Posted by JonB View Post
    Has anyone got any spare they would like to dispose of?
    Can't help with spares, but have you though of replacing them with 4164s or 61256s instead.

    Code:
    Use 4164 RAMs in place of 4116 RAMs
    
    
    
    The 4116's used in the early Apple IIs run very hot and are fairly 
    unreliable. They require +5v, +12v, -5v and 0v for power. We can 
    actually adapt a more common 4164 RAM so it will fit into a 4116 
    socket. This RAM runs much cooler, requiring +5v and 0v only, and 
    tends to be more reliable.
    
    
    
    Let's have a look at the pinouts of the 2 types:
             ___  ____                  ___  ____
       -5v -|1  \_/ 16|- Gnd      N/C -|1  \_/ 16|- Gnd
       Din -|2      15|- /CAS     Din -|2      15|- /CAS
       /WE -|3   4  14|- Dout     /WE -|3   4  14|- Dout
      /RAS -|4   1  13|- A6      /RAS -|4   1  13|- A6
        A0 -|5   1  12|- A3        A0 -|5   6  12|- A3
        A2 -|6   6  11|- A4        A2 -|6   4  11|- A4
        A1 -|7      10|- A5        A1 -|7      10|- A5
      +12v -|8       9|- +5v      +5v -|8       9|- A7
             ---------                  ---------
    
    
    OK, well the data pins are all in the correct places but we'll need 
    to do something about the power supply pins which are needed for the 
    4116 but not the 4164. Also, the 4164 has 4 times the capacity of the 
    4116 so we'll need to address that too. This turns out to be really 
    easy, the A7 pin of the 4164 is in the same place as +5v on a 4116, 
    so we don't need to do anything here and A7 will be tied high. Pin 8 
    of the 4164 (Vcc) will be connected to +12v unless we do something 
    about it. We bend the pin so that it won't go into the socket and 
    jumper it to +5v - the easiest way to do this is to connect it to 
    pin 9 on the other side of the chip. The surplus length of the bent 
    pin 8 can be snipped off. Finally, pin 1 of the 4164 should not be 
    connected to anything but will be connected to -5v if placed in the 
    socket for a 4116. We can simply snip off this pin and all is well. 
    This procedure can also be followed to use a 41256 as a 4116. Also 
    in the IIe 80 column/64k card, you can bend up or remove pin 1 of 
    a 41256 to replace a 4164. I have one with 2 such chips inserted and 
    it works fine. I also have a II+ with a chip such as described above 
    and no problems. If you need to or simply want to try this, and are 
    not sure, simply email and I'll walk you through it. 
    Thank you for reading. 
    
    This page has been formatted for People using Apple IIs accessing 
    the internet.
    I cannot take credit for this - I had it bookmarked from here: http://picmania.garcia-cuervo.net/re...16_to_4164.htm


    CP/M-86 Software Repository www.eolith.co.uk

  5. #5

    Default

    I also think jameco has them but hit me up if you get desperate, I think the local junk shop has some NOS tubes of them. I'm in the US so shipping isn't pleasant but I might be able to.

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