Oops, yes of course, 100 ns (the 6000 series "minor cycle time", the master clock period). Thanks. If anyone is interested, the bits are open for inspection at svn://akdesign.dyndns.org/dtcyber/trunk -- the VHDL is in the "vhdl" subdirectory and the attempt at a SPICE model in the "spice" subdirectory. The console emulation is dd60.cpp. paul

UHF, yes, but not those. The final state uses 3CX100A5 UHF transmitter tubes. The 2C43 would not appreciate the 2000 volt plate voltage used in that stage. The driver stages are fairly ordinary looking receiver style dual-triode tubes. Really? It is shown as a K2263-P31, manufacturer Fairchild Camera and Instrument Corporation, Defense Products Div., Clifton NJ. I sure would like to get my hands on specs for that tube. In any case, they were sometimes referred to as "radar tubes" which sounds somewhat reasonable. Certainly very different from TV CRTs, and bigger than what's used in oscilloscopes, so they were most likely low volume which would explain a high price. paul

The crazy thing about the 6000 series display controller is that it doesn't use tables at all. The selection of what stroke step to produce for a given character and point in time is defined by a very large collection of gates. The 170 controller does use table lookup (a ROM with the equivalent information). I wonder why a ROM wasn't used in the 6000. Perhaps they couldn't find a cost-effective technology that's fast enough? Core rope would work just fine for this, but not at 100 ns cycle time. paul

Yes. "Same length wire" is how I first heard it. When I started reading the 6600 wire lists I discovered that the reality is far messier. The PPUs aren't too bad, that is a 4 phase clock, where consecutive stages are clocked usually at 50 or 75 ns apart. For example, the consecutive stages of the barrel are clocked (mostly) at 75 ns difference. The CPU is much worse. It sometimes has 4 clock phases, but some parts look more like 6 or 7. If you study the block diagrams you'll see clock signals annotated by their offset from the zero reference, in increments of 5 ns. Not quite all of the 20 possible offsets are used, but more than half are. And it matters, as I found out the hard way while trying to get a VHDL model to work. The model includes the nominal gate delay (5 ns) and the rounded wire delay in 5 ns multiples for "long enough" wires. That mostly works. Replacing the clock tree by explicitly coded 5 ns multiple clock signals makes it better. Sometimes the documented value isn't quite right and you need to move things by 5 ns. Sometimes the same document gives two different timings for the same clock signal on different pages. Oh yes, then there are amazingly nutso things like flip-flops (which in the 6600 are R/S flops) where the R and S inputs are asserted at the same time, with pulses that both rise and fall roughly at the same time. I can fudge that. But it makes me wonder why the 6600 ever worked in the wild. For example, in the instruction issue and instruction stack logic I can get an "eq *-2" to work the first time and the second time but not the third: "not in stack" works, "in stack" works the first time because the "inch" is still underway, but by the second time the inch has stopped and my timing is off by 5 ns and things go utterly haywire. By tweaking nanoseconds I can move the problem but I have not yet made it go away. One place that does offer a fair amount of sanity is cross-cabinet connections; the coax cables are all the same and the nominal delay including driver and receiver is 25 ns, which nicely matches the semi-standard 4 phase clock. So tracing signals around a pile of cabinets works pretty well. Some of the data paths are quite amazing, because the memory fan-in and fan-out is routed through several other cabinets and the control signals are routed separately yet again. Tracking the signals for an exchange operation, for example, is quite an impressive dance of actions being launched fairly long in advance so they get to the memory latches at just the right time. paul

Speaking of CDC 6x00/Cyber 70-series consoles... I had a bit of a scary but memorable experience of sitting at the console of a Cyber 73, many years ago. My job as a systems operator basically involved watching the console for magtape mount/dismount requests, printer service requests (e.g., out of paper), as well as in general monitoring the loading of the system, and assuring that all was running smoothly. The machine was running the KRONOS timesharing OS, with MODCOMP front-end communications processors providing serial terminal services. There were two MODCOMP machines (not sure of the model, but would recognize them) that provided literally 100's of serial ports for terminal access through, in the earlier days, various port-selector equipment, and later, through a Sytek LAN-based terminal server networked together with thin coax strung around the buildings. Anyway, I was sitting at the console one morning, and noted that very suddenly, the left tube's image coalesced into a single vertical line centered in the tube. At the same time, I heard a quiet cracking noise coming out of the area of the console where the CRTs and final drive circuity was located. The cracking noise very quickly increased in intensity, and then the vertical line of the left display (the right display stayed normal), suddenly collapsed into very bright dot in the center of the screen, then all at once, there was a loud BANG, the dot on the screen faded away quickly, the right screen went blank, and I was greeted by a shower of sparks and molten metal that spit out the slot underneath the tubes where the deadstart switch was located, and smoke coming out of the cooling slots in the cabinet. Then, there was a clunk (someone throwing the power switch for the console), and everything settled down fairly quickly, other than there was a lot of stinky smoke in the air. This whole sequence of events occurred in about 2 seconds. I had just enough time to push my feet against the electronics bay underneath the console, and shove myself away from the shower of sparks. I ended up with a small chunk of molten metal that landed on my left leg and burnt through the fabric of my slacks and burned my skin pretty good. There was a lot of acrid smoke that also came out of the console for a little while after the power was off. We were concerned that there was a fire in there, but as it turned out, fortunately, there wasn't. Other than the burn on my leg and a little hole in my slacks, I was unscathed. But, I was a bit stunned by what happened, and it took me a few moments to realize what had happened. The other people in the data center reacted quickly. One that was dismounting a tape on one of the drives that were situated behind the console by about 10 feet, ran to the master power switch on the console and shut it off. Another ran to me, and was checking me out to make sure I was OK. One of the other folks started up a magic program on the Cyber from a Tektronix 4023 terminal in the data center that effectively provided the same displays as the Cyber console, except only one of the displays could be viewed at a time. The display was updated using the addressable cursor of the 4023 terminal, though it wasn't nearly as "real-time" as the actual console displays. Commands could also be given in the same form as they could be keyed on the console keyboard. This served as the alternate console while the main console was dead. The smoke detection system in the data center triggered the fire suppression system (Halon in those days), and the klaxons went off indicating we had 30 (maybe it was 45, can't remember for sure) seconds to get out of the room before the Halon dumped and all the oxygen was flushed from the space. There was an abort switch on the back wall of the data center, and one of the other folks ran and hit the abort to keep the Halon from dumping (which was rather expensive to recharge). The fire department showed up almost immediately, because they were A) located at one corner of our business campus, and B) their station was tied into the fire systems in the data center, and were notified when the smoke sensors triggered. They came and checked everything out to make sure no lingering hot spots could spark fire. After the ruckus settled down, I resumed monitoring the system with the 4023 terminal, and operations proceeded normally. The outage of the console had no effect on the operation of the Cyber -- everything ran along just fine during the chaos. End users generally didn't even know it happened. We had onsite CDC service engineers, and they responded immediately. It turned out that one of the big driver tubes had failed in such a way it shorted, and that caused a cascade failure that eventually took out the other tube, and caused some pretty severe stress in other components in the high voltage power supply that ended up drastically overheating, resulting in the shower of sparks and some hot metal. One of the CRTs (the left one) had to be replaced. When the beam went to dead center, it burnt the phosphor out at that point. Both of the big final-stage driver tubes had to be replaced (even though only one had failed, they apparently had to be replaced in pairs). Some smaller vacuum tubes, wiring harnesses, circuit boards and IIRC, a transformer that were cooked also had to be replaced. Also, a few of the circuit modules in the base cabinet of the display were replaced. They had the console back up and running smoothly in a little over 4 hours. Amazingly, their local parts depot had everything they needed to repair the console in stock. One engineer ran into town to pick up the parts while the other tore into the console, and by the time the guy arrived with the parts, everything was stripped down, cleaned up, and ready for the new parts to go it. The little "fireworks" display I was front and center to witness will be something that I'll never forget. -Rick -- Rick Bensene The Old Calculator Museum http://oldcalculatormuseum.com

Paul wrote, concerning my "fireworks" show on the DD60 console of Tektronix' Cyber 73 system: X/Y drive chains. It's all differential, so there are four of everything, ?>ending up at the pair of X and pair of Y plates of the CRTs. The X/Y amplifiers connect to both tubes. The reason you see two separate >displays is that the tubes have separate unblank circuits. So the same character waveforms go to both, but at any given time only one controls are separate for the two. See the schematics. things like that, but it sure is hard to figure how that would cause This happened probably somewhere between 35 and 40 years ago. I'm going it's possible that I some bits were dropped or flipped over the ages. Believe me, the console did spit out a lot of sparks and little blobs of molten metal, along with quite a bit of smoke. I still have a small scar on my left leg where one of the little blobs of metal burned me after burning through the material of my slacks. I remember keenly one of the CDC field guys saying that one of the big driver tubes had shorted. There were quite a slew of other parts (including some smaller vacuum tubes) that ended up being replaced, as well as the left CRT tube which had a phosphor burn right in the center. What I observed, I remember quite clearly, although a lot happened in a short time, and it's entirely possible that the right tube may have also had something weird going on while I was watching what was going on with the left tube. I happened to be looking at the display up on the left tube when the failure occurred, so my attention wasn't directly on the right tube. I remember glimpsing quickly at the right tube noting that its display had disappeared as I was pushing the wheeled chair away from the console with my feet. Whatever the cause of the failure, it was something that surprised the CDC guys. Maybe the shorted tube was an artifact of the failure, and not the cause...hard to remember exactly. But, I do know that two of those big ceramic and metal tubes were replaced, as well as the left CRT, and a whole slew of other parts. And I do clearly remember them saying that the driver tubes had to be replaced in pairs. Anyway, all told, it was an interesting adventure. I loved those days...I have a photo of myself sitting at the console of that machine back in the day...probably some of the happiest times in my work career were those days at Tektronix. -Rick

This reminds me of every TV show and movie I've seen where consoles begin exploding on a space ship during a battle. All of this time, I thought that was entirely a Hollywood fabrication! -- Mark J. Blair, NF6X <nf6x at nf6x.net> http://www.nf6x.net/

Paul Koning wrote: I wish more terminal emulators had this attention to detail! There's one called cool-retro-term which looks nice, but it's only mimicing superficial appearance.