Big apologies to everyone who wanted this information, but had to wait. I've been too busy, lately. I benchmarked NJRAMD, Ray Duncan's EMS DISK, IBM DOS 3.10's VDISK, and my Seagate ST-238/Adaptek 2070A RLL hard drive subsystem with eachother. The first important point is how much DOS memory each of the drives take: Seagate 0 bytes NJRAMD 705 bytes EMSDISK 836 bytes VDISK.SYS 1048 bytes Of course, the Seagate doesn't require any DOS memory, as all of it's control routines are stored in the ROM on the controller card. NJRAMD takes slightly less memory than EMSDISK because I've used some extremely efficient programming methods. Just the bare essentials are left in memory when NJRAMD loads. It seems that EMSDISK leaves around a lot of "work space" and "temporary" variables, that don't even need to be there. Much of NJRAMD's code is shorter, also. VDISK.SYS takes a great deal more memory than NJRAMD because VDISK is a much more powerful program, in a way. It provides code for a RAM Disk for either regular DOS RAM, or for the Extended memory that AT systems have. NJRAMD only provides a RAM Disk for the EMS and EEMS memory systems. The other important consideration is speed. NJRAMD proved faster than either of the RAM Drives, and certainly faster than my hard disk drive. (The times for the hard disk drive are included only for a reference.) My system runs a 4.77 MHz NEC V-20 CPU. I wrote a simple program using SYMDEB, Microsoft's Symbolic Debugger, to test the drives. I ran the program three times, and took an average of the three runs. The first version of the program is simply a loop that executes 10000 times. In each iteration, the program reads one 512-byte sector from the drive. The program always reads the same sector. All in all, 5,120,000 bytes of data were transferred during the test. These are the results: Program Try 1 Try 2 Try 3 Average NJRAMD 36.01 36.03 36.02 (36.02) NJRAMD, /S option 35.60 35.71 35.63 (35.65) EMSDISK 36.53 36.73 36.45 (36.55) VDISK.SYS 1:01.46 1:01.38 1:01.42 (1:01.42) Hard Drive 2:47.30 2:47.45 2:47.53 (2:47.43) NJRAMD and EMSDISK ran neck-and-neck for this first test; NJRAMD was only negligably faster. My hard drive turned out a reasonable time, considering that it's not buffered. It seems strange to me that VDISK.SYS was so much slower than the other programs, however. I checked my tests several times, and they seem to be correct. VDISK.SYS seems to execute with very much overhead. I would have thought that VDISK.SYS would've been *faster* than the EMS drives, since VDISK doesn't have to deal with the overhead of the EMS manager, as the information is right in standard DOS memory, and doesn't need to be bank-switched into place. The second test is also a loop that executes 10000 times. Each iteration, however, read eight sectors, starting at the seventh logical sector of the drive. In total, 40.960 million bytes of data were transferred. These are the results: Program Try 1 Try 2 Try 3 Average NJRAMD 1:46.75 1:46.64 1:46.68 (1:46.69) NJRAMD /S 1:45.80 1:45.73 1:45.89 (1:45.80) EMSDISK 2:11.07 2:11.30 2:11.12 (2:11.19) VDISK.SYS 1:17.78 1:17.70 1:17.60 (1:17.69) Hard Drive 5:34.10 5:33.96 5:34.12 (5:34.06) In this test, NJRAMD's special optimizations are shown. Since DOS, and application programs under DOS, often read or write several sectors in a row, I thought it would be beneficial if NJRAMD had logic to account for this. As the results show, the idea payed off. The program became significantly faster than EMSDISK. VDISK.SYS had only slightly slower times, which, again, suggests that the program has some sort of large speed overhead, wasting time in its execution. My Hard Drive again performed as expected. The mechanical device read the data at approximately 122000 bytes per second, which is rather good, considering the limit placed on DMA transfers in my relatively slow system. NJRAMD is avaialable in the file NJRAMD.ARC, here in the IBM Software Forum. If you'd like a copy of the program on a special pre-registered disk, send $10 to Mike Blaszczak 112 Verlinden Drive Monroeville, PA 15146-2041 13 May 1987