KVC@ENGVAX.SCG.HAC.COM (Kevin Carosso) (07/23/87)
> Here's a public domain version of a RAMdisk for VAX/VMS V4.n that > actually works pretty well. It takes its space out of your non-paged pool, > which means you'll probably have to re-adjust some SYSGEN parameters for > anything of significant size. The device driver PDDRIVER.EXE is UUENCODEd. > If you don't have the UUENCODE/UUDECODE program set, let me know and I'll > re-send it in a format you can decode. The PDDRIVER that was distributed is NOT a public domain driver. It is an undocumented device driver distributed by DEC with VAX/VMS since VMS V4.0. First off, everyone already has it. Secondly, I doubt DEC appreciates having their code distributed as "public domain". On the other hand, this thing is minor enough that I doubt they care. You should be more careful with what you distribute. I must say too, it is somewhat flattering to see my personal Pascal coding style go by... I wrote FORMAT_PD.PAS and sent it out to the net YEARS ago! (Note: it IS pd, I'm not upset at all seeing it distributed, of course!) By the way, one thing to note on PDDRIVER that has come up in the past. Before everyone decides "RAMdisks" in general, and specifically PDDRIVER, are the great panacea, I'd like to make a few comments. 1). "RAMdisks" sound great on a PC, but on a virtual memory machine? yuck. How about applications using their address space... (no flames please I realize it can help, this is just my gut reaction... I'm sure no one wants to hear another great debate on the issue) 2). According to VMS development, PDDRIVER moves data in a loop, a byte at a time. It is, therefore, extremely inefficient. You trade some I/O waiting time for a lot of CPU cycles using it. It might be improved dramatically with a MOVC instead. 3). It eats non-paged pool, so bump up your SYSGEN params accordingly. You can release the memory the disk uses back to pool, but the memory remains allocated to non-paged pool, so the system cannot use it for anything else after you reformat the disk to size 0. /Kevin Carosso kvc@engvax.scg.hac.com Hughes Aircraft Co. kvc%engvax@oberon.usc.edu