*** The DECserver Frequently Asked Questions file *** *** Last updated 10-MAY-2025 04:46:56 by TMK *** Q1: Why isn't this on Bitsavers? A1: That's a REALLY good question. As the creator of much of the material, I contacted Al Kossow regarding the nascent DNAS area, both making suggestions for a better presentation as well as mentioning files that should be there but weren't, or which shouldn't be there but were. I also supplied (at his direct request) photographs of equipment, which as of this writing haven't made it onto Bitsavers. I've had no reply from Al to any of my email, so I don't know what's been going on. Rather than continuing to tilt at windmills, I've gathered it here. Plus, I can have manuals and soft- ware for each model in a single directory, while Bitsavers usually splits those into separate documentation and soft- eare trees. Q2: Why you? A2: I've been using DECservers since the DECserver 200 was in- troduced in 1986, had my suggestions incorporated into fu- ture server models, was contracted by Digital of Canada to write a DECserver load/dump package for RSTS/E in 1990, and purchased the DNAS 2.4 CD and shared it with the community, so up to recently most people have been using stuff I was involved with, even if they don't realize it. I've also been an active participant in discussions about DECservers on the Vintage Computer Federation Forums since 2018, having joined the year previously. I've been active in DECserver support ever since, most recently in inspiring the project to design a replacement power supply for the DECserver 700s, as well as obtaining a copy of the last ever software release (DNAS V3.6) for the DECserver 700, 900, and some Cabletron models. Q3 : Blah, blah, blah... What's a DECserver and why would I want one? A3: Lets start with the easy part - a DECserver is a device to connect multiple serial terminals (and occasionally other devices) to DEC (and subsequently Compaq and HP) minicom- puters - PDP-11, VAX, Alpha and later Integrity (better known as Itanic) systems, using a responsive protocol with minimal overhead (remember, "high speed" links in those days were 10Mbit/sec "Classic" Ethernet links). Initially the DECservers spoke this proprietary protocol (LAT - Local Area Transport) exclusively, although later models and new- er software added TCP/IP support to some configurations. The second part depends. Maybe you're at a company that is still using them (such environments really do exist). May- be you're a hobbyist interested in retrocomputing and want to see how terminals connected to DEC systems many years ago. Maybe you found a funny old box labeled "DECserver" and just what to know what it is and if it's worth anything. The third part is if you just want to connect a 40-year-old device to your newest computer / operating system, just for the fun of it. The Linux-DECnet package includes LAT support, and LAT support is available as a separate package in case you don't want to run a full DECnet protocol stack or you're using one of the systems that the DECnet part doesn't compile on. A good overview for Linux can be found at: https://retrocmp.com/how-tos/connecting-a-decserver-to-linux For FreeBSD: net/latd port/package For NetBSD: net/latd port/package For Windows: While there used to be quite a few vendors sell- ing LAT implementations for Windows, most of them stopped working after Windows XP (or earlier, depending on the par- ticular package). Q4: Why the fascination with the DECserver 700-08 and -16? A4: These were the last standalone units build by DEC. Sub- sequent units went into DEChub chassis or required a stand- alone power adapter. The 700-08 and -16 can run the very last DNAS software (V3.6). Q5: Are there any bad things about the DS700-08 and -16? A5: Unfortunately, the plastic of the DECserver 700-08 and -16 is extremely fragile, due to a combination of the type of plastic used, exposure to sunlight for many years and the metallic coating applied to the inside of the case (to meet FCC requirements) means that finding a visually perfect unit is nearly impossible. Further, opening the chassis is fraught with danger, as it really requires at lest 3 hands (one to depress the left tab, one on the right tab, and one to use the screwdriver slot between the tabs to begin to VERY carefully separate the top and bottom half of the case. You will quite likely split one or both of the cover release tabs vertically along the injection mold line. Don't worry about it as it is "out of sight, out of mind" - just try to avoid causing additional damage. Be careful when separating the bottom and top half of the chassis - it uses a slight lift and pull forward type operation. Note: If you have the snap-on rack-mount rails attached, I'd suggest leaving them attached and not trying to open the chassis. The will likely snap some of the side ribs on the upper part of the case. Since you'll probably only get one shot at opening the case, you'll probably want to install everything you want in that one operation: Flash card (if supported by your model), 8MB of RAM (2 * MS40-WB), and the newest available boot EPROM. On auction and reseller sites you will see many DS700 cir- cuit boards for sale, This is likely because the cases shattered when the user tried to open them. In some cases the power supplies (if working) were sold for exorbitant prices - $600 and up seems to be the going rate, although look on this site for info on a redesigned power supply that is much more reliable. If your DECserver 700 isn't flash-capable and you can find a board with the flash slot (and ideally a flash card; these units are very picky about the cards they will accept), it might be worth doing the upgrade "as you're in there any- way". Test before putting the top back on, though! Q6: What about the DECserver 90 and 900 family? A6: They can generally run the latest DNAS 3.6 software. The issue is that they were generally pulled out of 90- or 900-series equipment shelves (the shelves included the power supplies, and power supplies for stand-alone modules are practically unobtainable at this point, at any price). The pinout of the power connector is known and you can make something up, but you no longer have an original- appearing unit. Q7: And the Cabletron / Digital Networks / Vnetek models? A7: It is very rare to see them come up for sale. If you aren't concerned about maintaining a "Classic DEC" look and you can find one at a good price, go for it - being much newer, these units are likely to be quite a bit more reliable than the older models. Q8: Well, how about the older DEC models? A8: Most of them only do LAT (the DECserver 300 with extra memory is an exception) but these are much older. The chassis construction is a lot more robust than the DEC- server 700-08 or 700-16, with a screw-on top and bottom plastic piece over a metal internal chassis. Note that if you plan on rack mounting one of these, be sure you get one with the brackets - the ones that were used as tabletop units have probably had their rack ears thrown away decades ago. Of all of these, probably the only interesting ones are the DECserver 250 (has 2 parallel ports for LP25/26 or similar lineprinters) or the 300 (TCP/IP support). Although if you just want to get your "feet wet" with DECservers, the older models can often be a bargain. A9: And the DECserver 500/550? A9: Those were large chassis which could take modular line cards - CXY08 for 8 ports with modem control, CXA16 for 16 ports without modem control, or the CXM04 which sup- ported 4 3270 terminals in either pass-through (to an IBM mainframe host) or local (connect to a DEC host) mode. You could have up to 128 terminals (using 8 CXA16 line cards) in a 550. One advantage / disadvantage was that the 500 series used PDP-11/53 CPU boards and DESQA Ethernet cards, while almost all other DECserver models used various Motorola 68K-family parts. This led to many of them being converted to PDP-11/53 computers (it is a simple boot ROM swap). But they can be converted back just as easily. One drawback was that since these were generic 11/53 systems, the configuration had to be done on a host VAX using the TSC (Terminal Server Configurator) utility, as opposed to via console commands as on the other models. This required keeping images synchronized if more than one load host was going to be serving the boot images, and also required a VAX to run the TSC utility. [As far as I know, TSC was never offered for Alpha and definitely never made it to Itanium). [more to be added]