SAGE@LL.ARPA (10/07/87)
I received the following question from Ken Wallewein. Since the answer may be of general interest, I am posting it to the entire list. :: I was wondering about ZCOM. I've read that it's the low-class way to :: go, that it uses up a lot of TPA, and that real hackers will do a :: proper implementation. What's the scoop? It there really a penalty for :: using ZCOM? I wonder where you read that ZCOM is a low-class way to go. It's true that it does not give a programmer a chance to display his skills at modifying his BIOS and reconfiguring the operating system. It is also true that ZCOM offered less flexibility in the definition of the system (it had RCP, FCP, NDR, and IOP buffers of a size determined by Joe Wright). And finally, ZCOM does cost an extra 0.5K of TPA compared to the same system installed manually (assuming the manual system has cleverly written BIOS modifications). However, we have a new version of ZCOM in the works, called NZCOM, that, in my opinion, will make manually installed systems undesirable and obsolete. Right now, for example, I am having trouble getting WordStar 4 to run on my system (manual installation) because there is not enough TPA. If I had ZCOM, I could just drop out of ZCOM and run WS4 under CP/M. Under the new NZCOM, one will be able to create complete Z-System configurations dynamically, on-the-fly! When you want to run WS4, an alias script justs commands the system to drop any RCP and IOP and to go to a small FCP while WS4 is running. This might give you back up to 4K of TPA. When WS4 is finished, the alias could automatically restore the original, more complete Z-System. When you want to make use of an IOP, like NuKey, for example, you invoke a NuKey loading alias. It checks to see if the current system supports an IOP of the necessary size. If not, it commands the system to allocate space for and initialize an IOP. It then loads NuKey, and away you go! When you're done, you can tell the system to drop the IOP if you want to recover the 1.5K of TPA. This kind of freedom will cost only 0.25K of TPA in any given system compared to an equivalent manually installed system. That is a VERY small penalty to pay for the freedom gained. It is even possible that because one does not need any ZCPR3 code in the BIOS coldboot routine, the BIOS might become shorter, and the net penalty might even be zero. In summary then, the autoinstall approach is not at all a low-class way to get a Z-System, and with NZCOM it will become the smartest way to do it, because it will give by far the most powerful implementation. No more will you face the dilemma of whether the features of ZCPR3 are worth the cost of the TPA lost. You will be able to trade off features and TPA on a command- by-command or task-by-task basis. -- Jay Sage