the uVAX II has a Q22/Q22 backplane so the positioning of the TQK50 is important, as is the RQDX(2/3) disk controller which should be last on the bus. The first 3 slots are CD types and are reserved for CPU/Memory, the rest (I can't remember which size cab you've got) are serpentine so if you've only got the CPU, 2 mem boards and the disk/tape controllers then the TQK50 should be on top of the RQDX3. I notice 8 TX lines which means there's a quad-height DHV11 there, probably next to the memory. If you've got a DEQNA ethernet half-height board as well then that'll mean you have TQK50/DEQNA occupying a quad-height slot and the RQDX3 on its own in the AB side of the slot next to that. Google for 'vax q22/q22 backplane' and you'll find an excellent explanation of how the uvax backplane works. cheers a/w

Yes, using the DS3662. Unfortunately it has been discontinued, as was the DS8641. Surplus DS8641 chips seem to be not that hard to find, I'd probably use those. CD4000 CMOS drivers and receivers have nowhere near the required specs. FPGA port pins have nowhere near the required specs either. No. Series termination on a multidrop bus is NOT viable. You have to use Thevenin or Thevenin-equivalent termination on the ends of the bus only. Still nowhere near the required specs. AFAIK, if you get drivers and receivers that meet the required specs, they will work fine for Qbus, Unibus, and Omnibus. The required specs are: Driver: Vol: 0.7V max at 70 mA - rules out 4000 CMOS and all FPGA pins leakage: 25 uA max, with Vcc from 0V to 5.25V capacitive load: 10 pF max rise and fall times (10%-90% voltage) must be no faster than 5 ns Receiver: Vil: 1.3V max Vih: 1.7V min capacitive load: 10 pF max leakage: 80 uA max at 3.8Vdc, with Vcc from 0V to 5.25V I don't know of any current production parts that meet the Qbus specs. Most drivers don't meet the Vol spec at full current. The receiver Vil and Vih specs are hard to meet, as they aren't typical of logic parts. The leakage specs are also a problem for many parts. DEC used specially selected DS8641 chips. The closest current production chips I've found do not fully meet the specs, but at least come close in many regards: TI SN75138 TI AM26S10 Eric

Adrian Graham writes: I did know about the serpentine weirdness. It caused me a great deal of grief in getting the system to pass its self tests in the beginning, before I stumbled (quite accidentally) across hamster's digital$resources page on Qbus. However, I think you may have hit on something. The RQDX3 is not at the end of the bus. If memory serves (I'll verify this after I get home from work today), the backplane arrangement is something like this: A B C D +-------------------------------------+ | CPU | +-------------------------------------+ | Memory | +-------------------------------------+ | TQK50* | | +-------------------------------------+ | M9047 | | +-------------------------------------+ | RQDX3* | | +-------------------------------------+ | DHV11 | +-------------------------------------+ | ???? ** | +-------------------------------------+ | | | +-------------------------------------+ | | | +-------------------------------------+ * I may have these swapped, OR I may have the M9047 swapped with the TQK50 ** This is another board. I believe a general-purpose DMA interface. I'll check when I get home today. Another note, here's some more strange behavior from VMS, which I now believe may also be linked to a QBus misconfiguration: $ SET TERMINAL TXA0:/PERMANENT/INTERACTIVE/DEVICE_TYPE=vt100 %SET-W-NOTSET, error modifying TXA0: -SYSTEM-F-TIMEOUT, device timeout Here's the info on TXA0: $ SHOW TERMINAL TXA0: Terminal: _TXA0: Device_Type: VT100 Owner: No Owner Input: 9600 LFfill: 0 Width: 80 Parity: None Output: 9600 CRfill: 0 Page: 24 Terminal Characteristics: Interactive Echo Type_ahead No Escape No Hostsync TTsync Lowercase Tab Wrap Scope No Remote Eightbit Broadcast No Readsync No Form Fulldup No Modem No Local_echo Autobaud No Hangup No Brdcstmbx DMA No Altypeahd Set_speed Line Editing Overstrike editing No Fallback No Dialup No Secure server No Disconnect No Pasthru No Syspassword No SIXEL Graphics No Soft Characters No Printer Port Numeric Keypad ANSI_CRT No Regis No Block_mode Advanced_video No Edit_mode DEC_CRT No DEC_CRT2 No DEC_CRT3 Thanks John Willis

Seems to have worked! SHO DEV now has the following output: Device Device Error Volume Free Trans Mnt Name Status Count Label Blocks Count Cnt DUA0: Mounted 0 VMSRL5 184419 94 1 Device Device Error Volume Free Trans Mnt Name Status Count Label Blocks Count Cnt MUA0: Online 0 Device Device Error Name Status Count OPA0: Online 0 TXA0: Online 0 TXA1: Online 0 TXA2: Online 0 TXA3: Online 0 TXA4: Online 0 TXA5: Online 0 TXA6: Online 0 TXA7: Online 0 Device Device Error Name Status Count HXA0: Online 0 HXA1: Online 0 PTA0: Online 1 PUA0: Online 1 on 3/10/05 2:44 PM, Adrian Graham at witchy at binarydinosaurs.co.uk wrote:

On Thu, 10 Mar 2005 21:44:15 -0000, Adrian Graham <witchy at binarydinosaurs.co.uk> wrote: There are *3* CD slots in a BA23. Since I saw your reply that "this works", let me give you one thing to look for... make sure that there are no grant jumpers on the CD side of the DHV11 if you want to retain this arrangement. It's legal to tap power/ground when not using the CD socket for what it's for, but it's important not to short any CD data lines together. You would *need* those grant jumpers in place when putting the DHV11 in any lower slot (a Q22/Q22 slot), but you want them out in slot 3 (Q22/CD). Alternately, you could arrange the bus this way (and I _would_) A--B--C--D [ -- CPU --] [ -- MEM --] [TQK50][empty] [-- DHV11 --] [-- mystery card --] [RQDX3][empty] The grant chain goes down through the TQ50, across the DHV11, across the mystery DMA card, then down to the RQDX3. You could also put the M9047 grant card in the AB side of slot 6 and the RQDX3 in the CD side of slot 6, in case you wanted to leave room for a dual-height option later. -ethan

On Fri, 11 Mar 2005 01:15:44 -0700, John Willis <willisjo at zianet.com> wrote: Glad to hear it... but I didn't catch what kind of box this is in... my suggestion is valid for a BA23, but not a BA123. Given that you drew 9 slots, I figured you had a BA23, but feel free to correct me. Hmm... if you weren't getting interrupt and DMA grant passed, the machine wouldn't boot because the RQDX3 wouldn't be able to interrupt/make DMA requests (a side benefit of putting it last, I suppose - no boot is an obvious sign problems, whereas a machine that boots, but has problems with a device behind the RQDX3 might be harder for a novice customer to grasp the situation of). It's more likely there's a configuration problem than broken hardware, but that doesn't mean that it's impossible that you have an actual DHV11 problem. I just don't remember seeing device timeouts on serial adapters since most problems will make them not show up at all. I no longer have a copy of your "show device TX" output, but I take it you _have_ tried putting a terminal on TXA0 and pressing return a couple of times? Have you put a terminal on there and tried outputting any text to it (a DCL command procedure or a C program should do the trick)? One can attach serial printers to random ports, if you didn't know that. They aren't just for logins (when they are working, that is). I do not recognize either the HX designator or the DRQ3, but it sounds like some kind of DMA-based parallel interface. Perhaps you could try running the system with that out? I doubt there's an interrupt conflict, but testing with the simplest machine possible is a good technique to use to keep the number of variables down. Right... that _is_ parallel I/O... not typically used for printers, but can be used to interface to odd external logic, or some such. -ethan

On Fri, 11 Mar 2005 09:38:51 -0700 willisjo at zianet.com wrote: [...] Yes, this sounds like a BA23. But a BA23 is 3U. (AFAIK 1U == 1.75") You should also check the backplane type number. There may be different ones. But I saw only the variant with the three top slots being QQ/CD and the rest QQ/QQ serpentine. -- tsch??, Jochen Homepage: http://www.unixag-kl.fh-kl.de/~jkunz/

Ethan scribbleth: It does! Thanks :) -- adrian/witchy Binary Dinosaurs creator/curator www.binarydinosaurs.co.uk - the UKs biggest home computer collection?