🚀 go-pugleaf

In article <23OCT199210410721@reg.triumf.ca>, noel@reg.triumf.ca (NOEL) writes:
> In article <1992Oct23.113552.16472@news.th-darmstadt.de>, sysgaertner@cygnus.frm.maschinenbau.th-darmstadt.de writes...
>>what interface is the DUV11 ? I know it must be some sort of
>>sync. seriell interface and did cost 2347.- DM (in Germany).
>>But I'd like to know what speed it has, if it has DMA and most vital,
>>if I can plug it into my uVAXII and have it running.
> 
> 	from the DEC communications handbook 81-82
> 
> 	The DUV11 is a 9600 baud single line, program controlled,
> double-buffered device designed to interface LSI-11's to a serial synchronous
> line. typical use was a synchronous line concentrator or a front-end
> synch. controller to larger system.  This is not a DMA device.
> 
> 	This is all pre-microvax so I would hesitate to try and configure
> it.  It is q-bus so it may be possible, but I'm not sure it was full 22-bit
> addressing at that time. I would leave it out.

Q-bus cards do not decode references to CSR space by looking at the high 
bits of the address lines on the bus, but rather by looking at the "BBS7_L"
(bank seven select) line.  

The difference between 18-bit and 22-bit Q-bus interfaces only applies to DMA
devices.  

Even among DMA devices, you are perfectly free to use 18-bit DMA devices on a
MicroVAX, even if the MicroVAX is one that supports 22-bit Q-bus addressing.
The reason is that 22-bit addresses will only be used for DMA if the device
driver acquires map registers from the extended map register set.  The driver
must ask specifically for registers in this set, by calling one of the
IOC$ALOALTMAP... routines.  Drivers which call the regular REQMPR macro will
always use the standard map register set, reg. number 0 through 495, which
correspond to addresses which can be handled by an 18-bit DMA card.  Older 
cards that only support 18-bit DMA addressing will work fine in a system with 
22-bit addressing, because their drivers simply don't call the newer routines.

	--- Jamie Hanrahan, Kernel Mode Consulting, San Diego CA
Internals, drivers, networks, applications, and training for VMS and Windows NT
Internet:  jeh@cmkrnl.com, hanrahan@eisner.decus.org, or jeh@crash.cts.com
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