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:
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
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)
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
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
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.