bin@rhesus.primate.wisc.edu (Brain in Neutral) (07/26/88)
[Note: I'm posting this for someone else. I'll forward replies, but it would be better to send responses the the address below - Paul] ------ 18-bit Device on a Microvax II keywords: DMA device driver Q-bus We have built a Parellel DMA Interface in house. We have been unable to read anything from the device although I have successful accessed the different registers on the card.(I have verified this with a scope) I get an interupt and the word count goes to 0. I am trying to determine if the Microvax II can handle an 18 bit device. Is it necessary to have 22 bit addresses? The board does not have any more room on it to add the wires that would be needed for 22 bit addressing. Another thing I don't understand if your card accepts 22 bit address how do you get one. From what I understand you can't get one from ubasetup. The bits above 18 tell you the number of registers you need and the number of BDP's what ever they are. Thanks in advance for any ideas on this. Cathy Accettura Space Astronomy Lab University of Wisconsin cathy@larry.sal.wisc.edu
aida@porthos.csl.sri.com (Hitoshi Aida) (07/27/88)
In article <349@rhesus.primate.wisc.edu> bin@rhesus.primate.wisc.edu (Brain in Neutral) writes: >We have built a Parellel DMA Interface in house. We >have been unable to read anything from the device although >I have successful accessed the different registers on the >card.(I have verified this with a scope) I get an interupt >and the word count goes to 0. I also have made a Parallel DMA Interface for MicroVAX II using DCK-11 chipkit from DEC. Functionally, it is just like DWV11-B (not DWV11-W) and it has only 18 bit address. I wrote driver for 4.2BSD(ported to MicroVAX II by us) and transfered it to 4.3BSD with no ploblem. I advise you to test the DMA function of your interface under console. We used our LSI-11/73 to test our board. I think we can only use lower 256KB out of total 4MB of Q22-bus address space under Berkeley-distributed unix. Maximum byte count for one DMA transfer is usualy limited to 32767, thus there would be only a little performance benefit if we modify ubasetup to handle 22 bit address space. -------- Hitoshi AIDA (aida@csl.sri.com) Computer Science Lab, SRI International
dan@rna.UUCP (Dan Ts'o) (07/27/88)
In article <349@rhesus.primate.wisc.edu> bin@rhesus.primate.wisc.edu (Brain in Neutral) writes: >We have built a Parellel DMA Interface in house. We >have been unable to read anything from the device although >I have successful accessed the different registers on the >card.(I have verified this with a scope) I get an interupt >and the word count goes to 0. > >I am trying to determine if the Microvax II can handle an >18 bit device. Is it necessary to have 22 bit addresses? >The board does not have any more room on it to add the >wires that would be needed for 22 bit addressing. The Ultrix-32 / 4.3BSD IO code treats the Qbus as an 18-bit Unibus and thus 18-bit Qbus peripherals work fine. That is, as far as Qbus DMA devices are concerned, they never need to worry that they will ever be handed a 22-bit Qbus memory address to which they need to transfer data to or from. The IO subsystem maps the physical memory only into the first 256kbytes of Qbus memory. I believe VMS on the Microvax works the same way. I believe that the Microvax I does have problems in this area as I think it does not implement scatter/gather IO mapping. It is possible to put Qbus devices on the Microvax II that appear as part of the 4Mbyte of 22-bit Qbus space. See the QVSS driver for an example. I have implemented a driver for a Data Translation frame buffer/ grabber which allows the user program to directly access the frame memory which appears as 1Mbyte of Qbus memory. I hope, however, that the device you built uses BBS7 to access the device registers rather than a Qbus 18-bit (or 22-bit) address. Let me know if you have any more questions... Cheers, Dan Ts'o 212-570-7671 Dept. Neurobiology dan@rna.rockefeller.edu Rockefeller Univ. ...cmcl2!rna!dan 1230 York Ave. rna!dan@nyu.edu NY, NY 10021 tso@rockefeller.edu