IBM RT with 5085 graphics processor

joe lang jclang at
Sat Apr 7 06:14:34 CDT 2007

Jules Richardson wrote:

> I picked up a very nice RT system the other day from a list member 
> which includes the 5085 graphics processor and 5081 colour display. 
> We've just been setting it up today (or trying to), and an obvious 
> question arises...
> The 5085 has some sort of comms input ability on a BNC connector (and 
> output on another BNC, but that's terminated).  The RT has a little 
> "breakout box" which hooks up to the 5085 link card on one side and 
> has four BNC outputs on the other.
> My *assumption* is that one of these outputs (and the breakout box 
> came with a coax cable already hooked up to BNC #1) links to the BNC 
> input on the back of the 5085, forming the comms channel between the 
> 8085 and the RT.
> However, it would be nice if someone can verify this! The RT 
> documentation doesn't cover the 5085 link option (so far as I've found 
> yet, anyway). The 5085 documentation doesn't cover it either (as it 
> only details how to hook the 5085 up to the peripherals and then boot 
> the hardware).
> Obviously I'm a little reluctant to go randomly plugging cables in, 
> particularly as the breakout box has four BNCs on board - although it 
> could well be that the RT 5085 link board was capable of driving up to 
> four 5085 processors independently.
> Google seems to know almost nothing about the 5085 option :-(
> cheers
> Jules
this takes me back (way back)....

I used 5085's on 43xx series systems.
The 5085 connected to a channel adapter
IRRc it was a 5088
The 5088 had 4 bnc connections and each connection could
support more than 1 5085
5085's  could be  daisy-chained  by connecting the out from
one to the in of the next and terminating the last out.

I know nothing about a RT.. it may have the 5088 function built in.
If that is the case then (I would assume)

rt link board-->breakout box-->5085-->terminator
it would support more than 1 string of 5085s

joe lang

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