In SMART1 project 4 Mbyte DRAM modules of Samsung have to be checked against different types of nuclear radiation. For this purpose a test configuration was prepared, where the PC-bus was prolonged with a flat cable and at the end of the cable the 4 Mbyte module was installed on a small card.

In the status report "Total-dose irradiation test plan of DRAMs for SMART-1 project" of 17-th May 2000 (authors: G.Dajkó, J.Molnár, D.Novák, G.Székely), section 7 describes this software in the following way:

Four bit patterns are used (00H, 55H, AAH, FFH) to test the DRAMS. A pattern is written into the memory, left there for 10 minutes then read back and compared to the initial values. If the radiation changes the memory content, e.g. the expected and received values differ, the errors are registered. If the number of errors is less than 1000, then the pattern expected, the pattern received and the address of the memory location is saved to hard disk in a report file for further analysis. If the number of errors is more than 1000, only the number of errors is saved. After comparing the expected and received values, the memorz is filled with the next bit pattern. The number of errors will be normalized to the number of bits under test.

The most tricky part of program development was to access memory bytes on a given physical address. With the standard XMS or EMS handlers in MS-DOS one can use as much as 4 GB memories above the standard 640 KByte, but none of them can tell the physical address of the allocated memory. When looking for free softwares on the WEB, we found a package of Herman Dullink called FLAT, which is applied also in HIMEM.SYS among other applications. So we decided to modify the nice example for direct video accessing in the package to be able to read/write the test memory we have at the [2,10) Mbyte range. This wethod worked fine after we have extended it with A20 handling routines of Robert Collins found at ftp://ftp.x86.org/dloads/PMBASICS.ZIP.