7 Aug
2005
7 Aug
'05
9:17 p.m.
The VT-11 has lots of line drawing modes that the 1350 does not
offer.
Also the 1350 (and 1351, I have both) does not do such a good job
of equalizing the brightness of vectors of different lengths.
I think I have to reluctantly give the nod to the DEC 1350 in terms
of capability. But I think the HP's analog vector generator outperforms
DEC's digital vector generator.
----- Original Message -----
From: "Tony Duell" <ard at p850ug1.demon.co.uk>
To: <cctalk at classiccmp.org>
Sent: Sunday, August 07, 2005 3:27 PM
Subject: Re: HP2648A terminal
HP made the (excellent) HP1350 and HP1351 vector graphics boxes, but
these have no keyboard input capability.
I have a pair of the 1350s, and as I've mentioned here before, the design
is strange. They take in a subset of HPGL (that is, commands in ASCII,
numbers as ASCII-coded decimal digits) and turn them into vectors which
are then output as analogue X,Y,Z signals. The weird part is that there
is no processor or processor-like circuit in there, it's all hardwired
logic. 3 large PCBs of it. I have the service manual.
The 2 10-bit DACs on the 1350 mainboard have preset pots to tweak the top
6 bits (there are setting up instructions in the manual). For reasons of
the physical appearance (2 rows of pots) and function, I quickly named
this the 'graphic equaliser' :-)
Does anyone have the service manual for the companion HP1311 monitor? I
don't, and I've never seriously looked inside.
Vector quality is very very good, better than a DEC VT-11 IMO, but
the VT-11 is a bit more advanced (more capable).
The VT11 has a resolution of 1024*768, the HP is 1024*1023. Both are very
good devices for their time.
-tony