Subject: Re: MicroVAX I: in need of modern OS.
To: Anders Magnusson <>
From: Brian D Chase <>
List: port-vax
Date: 02/05/1999 11:12:39
On Fri, 5 Feb 1999, Anders Magnusson wrote:

> The kernel does not rely on any floating-point, so that's no problem.
> Does it use MTPR for console in/out? If it does, it will be simple to
> get the kernel to say at least "hello". 

I'm going to have to guess no on that one.  I'm not sure how console I/O
works on it, maybe like MicroVAX II? 

> Is there some sort of VMB in prom? How does the machine boot?

No VMB in prom.  It tries to look for it on the RD52 or RX50.  

> Part 2 of this is to make the uba routines to stop careing about map
> registers, but that will also be rather simple I suppose.

Based on what Matt Thomas said about the effects on DMA due to the lack of
these registers, will it really be easy to implement?  

Matt, I'm brushing up on my DMA I/O concepts with an old computer
architecture textbook, but I may require a more detailed explanation of
what you mean by doing DMA bounced or handling the scatter/gather

Without any mapping registers, how do the CPU and DMA I/O devices agree
upon locations for transferring blocks of data?

Brian "JARAI" Chase | | VAXZilla LIVES!!!