andyross@ddsw1.MCS.COM (Andrew Rossmann) (03/21/90)
Has anyone had any experience in loading DOS 4's SMARTDRV.SYS into the High RAM area made available by QEMM? Is it better to run SMARTDRV using extended memory, or use expanded memory under QEMM? (I know extended tends to be faster, plus I don't do any high-speed serial port reading.) Andrew Rossmann andyross@ddsw1.MCS.COM
dhinds@portia.Stanford.EDU (David Hinds) (03/22/90)
In article <2606b522-2621comp.ibmpc@ddsw1.MCS.COM>, andyross@ddsw1.MCS.COM (Andrew Rossmann) writes: > > Has anyone had any experience in loading DOS 4's SMARTDRV.SYS into the > High RAM area made available by QEMM? Is it better to run SMARTDRV using > extended memory, or use expanded memory under QEMM? (I know extended tends > to be faster, plus I don't do any high-speed serial port reading.) > I use LOADHI to put SMARTDRV in high memory, and it works fine. I'm not sure what the difference between extended and "expanded" memory will be under QEMM; for a disk cache, both are sufficiently fast that you won't see much of a net performance difference. I seem to remember that the DOS manual recommended using expanded memory for SMARTDRV, but this may have been aimed at 80286 systems. A reason that the 386's extended memory might appear faster than expanded memory is that to access extended memory, a program calls a BIOS memory move routine. To access expanded, a program calls the expanded memory driver, which remaps memory and lets the calling program do the move. The BIOS move will be a full 32-bit block move, while a program using expanded memory will probably use a 16-bit move instruction, for compatibility across processors. -David Hinds dhinds@popserver.stanford.edu
noelroy@kean.ucs.mun.ca (Noel Roy, Economics Dept., Memorial University) (03/22/90)
In article <2606b522-2621comp.ibmpc@ddsw1.MCS.COM>, andyross@ddsw1.MCS.COM (Andrew Rossmann) writes: > Has anyone had any experience in loading DOS 4's SMARTDRV.SYS into the > High RAM area made available by QEMM? Is it better to run SMARTDRV using > extended memory, or use expanded memory under QEMM? (I know extended tends > to be faster, plus I don't do any high-speed serial port reading.) > > Andrew Rossmann > andyross@ddsw1.MCS.COM I have been running SMARTDRV.SYS in high RAM using QEMM without problems. My tests indicated that loading SMARTDRV into extended memory directly was significantly faster than loading it into QEMM's emulated expanded memory. I forget the details, but the difference was something along the lines of 8 vs. 11 seconds. Dr. Noel Roy bitnet: NOELROY@MUN Department of Economics internet: noelroy@kean.ucs.mun.ca Memorial University of Newfoundland cdnnet: noelroy@kean.mun.cdn St. John's, Newfoundland A1C 5S7 Canada