Seen by pure coincidence on eBay and bought for little money. So far I only needed the D320 for my DRAM's.

The LCD display is a little faint, but at the right angle it is quite readable. I do not have a manual, but the procedure for testing is self-explanatory. A DRAM or LOGIC IC may only be inserted after the self test.

DRAM

The common old DIP or DIL DRAMs can be tested. So far I have only tested type 41 DRAMs for my IBM PC, XT and expansion cards.

• 41:000
• 4164 (64,536 x 1 bit - 8,192 byte - 8 KB)
• 41256 (262,144 x 1 bit - 32,768 byte - 32 KB)
• 411000 (1,048,576 x 1 bit - 131,072 byte - 128 KB)
• 44:000
• 4416 (16,384 x 4 bit - 8,192 byte - 8 KB)
• 4464 (64,536 x 4 bit - 32,768 byte - 32 KB)
• 44256 (262,144 x 4 bit - 131,072 byte - 128 KB)

The test duration is approximately 23 seconds for a 4164 and 47 seconds for a 41256 DRAM.

DRAMs of type 4116 unfortunately can not be tested, that would be too nice. This DRAM requires voltages of +12V and -5V. The Polar D320 has only a simple 9V battery and does not include a special DC/DC converter.

LOGIC

Furthermore, the Polar D320 can still test some ICs of the 74, 40 and 45 series.

I had paid absolutely no attention to the LOGIC IC test function until now (March 2022). And exactly this function I need now for my "possibly defective" Kaypro II 81-110-A motherboard and my S-100 boards for the N* Horizon and IMSAI 8080.

The way it works is just as simple as with DRAMs. Just plug it in the other way around, lock it, select the type and test it. The search function also works surprisingly well. Especially here it pays off, because for example with the 74 series you have to "press" a lot to select the right IC.

Of course, I can't say anything about the actual test and verification algorithm. This is just a black box for me. So far, however, everything seems to be in order.