DRAM Tester for ZX Spectrum, C64, Oric, Jupiter Ace and other retro computers and equipment.

This DRAM tester supports 1 bit DRAM devices from 4Kbit to 1Mbit (eg. MCM4096, M4027P, 4116, TMS4532NL3/4, M3723L/H, 4164, 4128, 41256, MCM511000 etc.).

Features of this tester not found in other DRAM testers:

  1. Support for 4Kbit parts (e.g. M4027 & MCM4096)
  2. Support for 32Kbit parts (e.g. TMS4532 & M3732)
  3. Support for piggybacked DRAM such as Samsung KM4128 used in early PCs
  4. Multicolour LED output to make the results simpler to read and more intuitive (e.g. working columns show as a horizontal bar, working rows as a vertical bar, fully working as a a square box)

As far as I know, this is the only tester available that will test the parts above, but this is essential if you want to keep the replacement parts in your retro computer kit the same as the original.

It has a simple power requirement, needing just 5V and drawing less than 100mA, so it can be powered from any USB port with a standard micro-USB cable. The tester generates all of the required voltages (+3V3, +12V, +5V and -5V) from this single supply.

How to Use

  1. Connect the board to a USB port to provide power

  2. Put the DRAM chip in the correct socket: The left socket is for parts that require -5V on pin 1, +12V on pin8, +5V on pin 9 and 0V on pin 16 (e.g. MCM4096, M4027P, 4108 and 4116), all other types should ONLY be tested in the right socket.

  3. Press the start button and wait for the result to show on the LEDs.

Please note that the LEDs will flicker while the DRAM is being tested, this is normal.

Example 16 Pin Parts That Need -5V(pin 1), +12V(pin 8) & +5V(pin 9) (LEFT SOCKET)

  • Mostek MK4027P
  • Motorola MCM4096
  • Mostek MK4108-x0
  • TI TMS4108-x0
  • Mostek MK4108-x1
  • TI TMS4108-x1
  • ITT/STC 4116
  • Mostek MK4116
  • Example 16 Pin Parts That Use a Single +5V Supply (MIDDLE SOCKET)
    Please do not put any of these parts in the left-hand socket. Testing any of these in there could damage the part and/or the tester

  • Mostek MK4516
  • Hitachi HM4816
  • Intel 2118
  • TI TMS4532xL3
  • TI TMS4532xL4
  • OKI M3732L
  • OKI M3732H
  • Hitachi HM4864
  • Micron MT4264
  • TI TMS4164
  • Samsung KM4128
  • TI TMS4256
  • Example 18 Pin Parts That Use a Single +5V Supply (RIGHT SOCKET)

  • Motorola MCM511000
  • Hitachi HM511000
  • Example Results

    LED Off

    No Block

    LED Red

    Bad Block

    LED Blue

    Good 4Kbit Block

    LED Green

    Good 16Kbit Block

    LED Magenta

    Good 64Kbit Block

    LED Cyan

    Good 256Kbit Block

    Part Size Socket Pass
    Mostek MK4027P or Motorola MCM4096 4 Kbit Left

    Mostek MK4108-x0 or TI TMS4108-x0 4 Kbit Left

    Mostek MK4108-x1 or TI TMS4108-x1 4 Kbit Left

    ITT/STC 4116 16 Kbit Left

    Mostek MK4116 16 Kbit Left

    Mostek MK4516 16 Kbit Middle

    Hitachi HM4816 16 Kbit Middle

    Intel 2118 16 Kbit Middle

    TI TMS4532xL3 32 Kbit Middle

    TI TMS4532xL4 32 Kbit Middle

    OKI M3732L 32 Kbit Middle

    OKI M3732H 32 Kbit Middle

    Hitachi HM4864 64 Kbit Middle

    Micron MT4264 64 Kbit Middle

    4164 64 Kbit Middle

    4128 128 Kbit Middle

    4256 or 41256 256 Kbit Middle

    MCM511000 or HM511000 1024 Kbit Right


    Test Times

    The tester is pretty fast, based on a modern 32 bit ARM micro-controller running at 64MHz.
    Here are some examples of the test times for this tester:

    Type

    Size

    Approximate Test Time

    4027/4096

    4Kb

    About 2 seconds

    4116

    16Kb

    About 5 seconds

    4164

    64Kb

    About 20 seconds

    4128

    128Kb

    About 42 seconds

    41256

    256Kb

    About 82 seconds

    511000

    1024Kb

    About 330 seconds

    The tests are made such that the refresh period is close to the specified maximum retention time for the part being tested.
    That means close to 4ms for 64 rows on an M4027 or MCM4096, 2ms for 128 rows on a 4116 part and close to 4ms for the 256 rows on a 4164 or 41256 part.
    This ensures that any issues that only occur near to the maximum retention time are also detected by this tester.
    So you can be pretty sure that if a part tests as good in this tester then it should work well in a real application.

    The Test Procedure

    1. Measure the size of the DRAM.
    2. High speed tests

    • Fill the RAM with 0s and check that
    • Fill the RAM with 1s and check that
    • Even Hash test
    • Odd hash test
    • Fill the RAM with random data and check that
    • Repeat the above random data test several times
    3. Lower speed tests to test the retention time

    • Fill the RAM with random data and check that
    • Odd hash test
    • Even Hash test
    • Repeat the above random data test several times
    • Fill the RAM with 1s and check that
    • Fill the RAM with 0s and check that

    For more details, please download the User Manual from here: https://athena.sieraybould.net/eBay/DramTester1Bit/DRAM_Tester_UserGuide_Rev6.pdf 

    If you have access to a 3D printer then I have uploaded a case for this to here: Case For 1 Bit DRAM Tester by SieRaybould - Thingiverse

    Please note that some of the photos show my earlier tester with two sockets. Apologies for that and I will update them ASAP. The photos are valid though for the left and middle socket on this new version and all previous DRAMs are supported. The only change is the third socket (18 pin) and support for 1Mb parts.