rusty (09/12/82)
I've always believed that dh's were better than dz's but the following appeared in "The DEC Troubleshooter" a Q&A column answered by Ken O'Mohundro (president of ABLE computer) in "Hardcopy" magazine: Q: I'm a VAX user and am finding that terminal handling is really slowing down my system. I'm being told that I should buy a DH11 lookalike and that will solve my problem. Since DEC doesn't support DH's on the VAX, I'm told that it would require a non-standard driver to make this work. This concerns me, and not being a hardware person I'm not sure what to do. A: First of all, I'm glad that your concerned! Anytime you are required to use non-DEC supported drivers you should be! If you are doing typical software development work or commercial aplications, a DH11 with or without special software will do that much good. Until I/O packet size exceeds 12-14 characters using a DEC DZ11 or approximately 45-50 characters using a ABLE VaxDZ, a DH11 will not outperform the standard software. That's considering the current versions 2.4 or 2.5; the newer version 3.0 is expected to be even better. The rumor currently is that version 3.0 is supposed to have a 25,000 character thruput as opposed to the current 11,000 character thruput. Unless you are doing large output packets, which bypass the driver terminal handling characteristics, I see no advantage in a DH11. In any event, I'd wait for version 3.0 from DEC before I made a selection that I'd have no recourse on. Remember drivers on one version may not migrate to easily to another version. Before DEC changes from a 2.x version to a 3.x version major changes needed to be made. There were some typos in the magazine; the "your" in the first sentence of the answer should be "you're", the sentence fragment "with or without special software will do that much good." seems to me is missing the word "not": "with or without special software will not do that much good.", in one place he does a billjoyism of using "a" when he should have used "an". Is Ken O'Mohundro feeding this guy a line? I know that Emulex is very good about supporting their devices on VAXen with device drivers for VMS, I don't know if ABLE supplies VMS drivers for their devices.