Re: Any difference between VAX Q-bus and PDP-11 Q-bus cards?
On 12/06/2017 09:55 PM, Jon Elson via cctech wrote: > On 12/03/2017 10:28 AM, Aaron Jackson via cctech wrote: >> I'm looking after a VAX 4000 for a friend, which has a SCSI Q-bus card >> (M5976). If the card did not have the large metal face, would it work in >> a Q-bus PDP-11? We are not going to potentially ruin a card by trying >> this, but I am interested to know if this is the case. >> >> > As long as the PDP supports the 22-bit Q-bus, it should work > perfectly. The metal plate can be removed. > > Jon Aaron, Save the plate though as they are scarce... MicroVAX used Q22. The thing to be wary of is the Q-bus spec allows for slots ABCD (wide) and also ABAB if its ABAB its easy and no big issues unless They can also be ABABAB (hex wide QBUS CORE). Whats that mean... AB is the address, data and control bussed connectors and CD are usually parallel bussed but may have odd voltages or order to the signals for some of the wide cards that (usually RL and Memory) need them. Its not unusual for a bus to be mixed like BA123 (uVAXII) where the first 3 or 4 slots are ABCD and the remaining are ABAB. IF the board requires ABCD such as the two board set RLV11 its important as the two board talk between them selves on the CD portion of the bus. Also many of the uVAX and some later PDP-11 (J11based) the CD bus was wired differently for memory. In most cases the ABCD portion of the uVAX backplanes are only a few slots and then it reverts to ABAB. FYI if your in the ABAB area make sure you keep the bus grants and interrupt grants continuous. I know of this as I have PDP-11 and uVAX systems from LSI-11 though uVAXII/GPX. They are all Q but there are more differences than Q16/Q18/Q22 due to the mechanical variations. Qbus board can be used in any system if they match the bus width (Q22 usually for uVAX) and you pay attention to where you put them. This includes a lot of the PDP-11 Qbus cards. Allison
Re: Any difference between VAX Q-bus and PDP-11 Q-bus cards?
On 12/6/2017 6:55 PM, Jon Elson via cctech wrote: On 12/03/2017 10:28 AM, Aaron Jackson via cctech wrote: I'm looking after a VAX 4000 for a friend, which has a SCSI Q-bus card (M5976). If the card did not have the large metal face, would it work in a Q-bus PDP-11? We are not going to potentially ruin a card by trying this, but I am interested to know if this is the case. As long as the PDP supports the 22-bit Q-bus, it should work perfectly. The metal plate can be removed. Jon The board will probably work in a 22-bit Q-bus, as you say, but only for certain values of "work" -- it won't catch fire or anything, but to the best of my knowledge the M5976 isn't an MSCP device and I don't know that any PDP-11 bootstraps or OSes know how to talk to it. So unless you want to write a driver for it, it's probably not going to be much use. - Josh
Re: Any difference between VAX Q-bus and PDP-11 Q-bus cards?
On 12/03/2017 10:28 AM, Aaron Jackson via cctech wrote: I'm looking after a VAX 4000 for a friend, which has a SCSI Q-bus card (M5976). If the card did not have the large metal face, would it work in a Q-bus PDP-11? We are not going to potentially ruin a card by trying this, but I am interested to know if this is the case. As long as the PDP supports the 22-bit Q-bus, it should work perfectly. The metal plate can be removed. Jon
Re: Any difference between VAX Q-bus and PDP-11 Q-bus cards?
On 2017-12-07 03:55, Jon Elson via cctech wrote: On 12/03/2017 10:28 AM, Aaron Jackson via cctech wrote: I'm looking after a VAX 4000 for a friend, which has a SCSI Q-bus card (M5976). If the card did not have the large metal face, would it work in a Q-bus PDP-11? We are not going to potentially ruin a card by trying this, but I am interested to know if this is the case. As long as the PDP supports the 22-bit Q-bus, it should work perfectly. I don't now that any OS supports the M5976 on a pdp-11 ... Electrically, you should be OK ...