Of GPIs and NMIs, have you reached your breaking point? From time to time you may experience an abnormal ending or abend. This abend surfaces at the file server. Any version of NetWare can report abends. Two specific abend messages are the most common, yet sometimes the most elusive to quell. These two errors are General Protection Interrupt and Non-Maskable Interrupt, respectively GPI and NMI, or, collectively, GPI/NMI. Reasons for their occurrence and what to do about them will be disclosed below. Often GPI/NMIs result from some hardware inadequacy. This deficiency could be as simple as insufficient RAM at the file server. For instance, most all versions of 2.1x NetWare require at least 1.5Mb of RAM to even boot and should they be necessary, begin to issue meaningful error messages. If you receive a GPI/NMI upon the initial booting of your file server before you see any of its initialization messages, save that of those from the cold boot loader, add more RAM. It is likely you have less than 1.5Mb at the time this GPI/NMI occurs. Remember that your memory needs to be of the type Extended. The other, expanded memory, is not utilized by file server processes. Encouraging other GPI/NMIs are, as a general rule, memory problems. Problems that can invoke memory problems include: *Power glitch, over- or under-voltage *Static electricity, generally an over-voltage *Phone wires, if there is a modem installed in the server and it is connected to an active phone line *Bad RAM chips Bad RAM covers an assortment of RAM problems. As a rule, all extended memory in a file server should at least be of the same speed rating if not of the same type. The speed rating is notated in nanoseconds (ns). Be especially sure to not mix memory chips of differing speeds on the same memory expansion board, though it is essentially "ok" to have two different memory boards utilize RAM chips of different speeds. However, it is important to use chips of a speed rating recommended by the board's manufacturer. Another RAM problem is that of defective chips. Realize that the break in period for most electronic devices falls in the period of 10 days. The first 10 days of time which they are active, i.e. power is appropriately applied, usually serves as the time in which make or break the chip. If you receive GPI/NMI messages within the first few days of beginning operation of your file server, consider that a RAM chip may have perished. Yet another problem is that of improperly installed RAM. When installing RAM be ultra-careful to make sure all legs of the chips are inserted into their specific sockets. As a final check, you can sometimes hold the up to your eyes in a level position and "peer" underneath the chips in an attempt to catch misaligned chip legs. Also, viewing from above can catch inappropriately installed chips. Though it is commonly known, not everyone recalls that RAM chips, as most electronic chips, must be installed in a particular way. Most RAM chips have a "half moon" on one end of the chip. On RAM chips this half moon is usually a physical feature rather than something drawn on the chip. And, correspondingly, on most memory boards there is a half moon indicator drawn around the memory chip socket. If you install a chip in the "wrong direction" it will be destroyed when power is applied. Sometimes it will go out with a bang, but, most of the time they just smoke. Also there is the seemingly odd problem of GPI/NMI messages occurring only during high amounts of activity on the network. This can be attributable to a RAM problem that exists high up in memory. Simply put, this memory is not accessed other than when the cache RAM begins to fill up. And when it is accessed, its arbitrary operation causes the abend to occur. Ways to resolve memory problems include: *Physical verification of proper installation -including: *correct RAM chip speeds *correct installation of chips into their sockets *Application of a power protection system -including: *line conditioner *battery backup *uninterruptible power supply *testing of power received at socket, your local power company probably has this available as a service *Test of RAM with such a tester, Brown Bag software makes a decent RAM testing program *Removal of RAM so that only a sufficient base of RAM exists -the idea is that if the RAM problem still occurs you can try swapping the excess memory with the base memory to see if you can quantify the error Other potential areas for GPI/NMI generation include any board in the file server. As an aside, with v2.0a and some clones, if a 1.2Mb floppy disk were inserted at the time the file server began to initialize itself, an invalid OP code interrupt, which is another abend message, would result. In any case, if you have tried to alleviate the GPI/NMI by checking your memory and it all checks out, you may have a malfunctioning card elsewhere in the system. Though this is not as likely a culprit because the afflicted card would probably result in some other noticeable error situation. With v2.1x of NetWare VAPs (Value Added Processes) and VADDs (Value Added Disk Drivers) were both added as options. Both represent a sort of application. Adding any type of utility to the server are VAPs. VADDs are added to specifically control disk drives and/or disk controllers. If you add one or more of these to your system and you suddenly begin to see GPI/NMI abends, it could be several things. Once again, it could be previously unused areas of memory causing the problem or it could the VAP or VADD itself. Just know that if you start receiving abends upon installing a VAP or VADD that it may be revealing a real memory problem rather than a deficiency in the added application. Moving outside the file server, other items which may masquerade as a memory problem include printers. Printers can invoke GPI/NMIs from two different perspectives. The first is that of spiking or surging the power source. This was covered earlier, just realize that it may be the printer causing the power fluctuations. The other problem stemming from printers is that of ungrounded cables. Most often associated with serially (COM port) attached printers, the lack of a connected grounding wire (pins 1 and 7 on the 25 pin connector or pin 5 on the 9 pin connector) can serve as an unstabling base for a GPI/NMI to occur. If a GPI/NMI error is not repeatable then it is likely the abend can be attributed to a transient power problem. The most prevalent reasons for GPI and NMI abend messages has been revealed above. With a little detective work, you can hopefully remove the source of your GPI/NMI demons. By JTM, Wizard SysOp and Brightwork Developer July 16, 1989 6:00pm