23 Apr
2006
23 Apr
'06
7:47 p.m.
This is a little strange!
A HP1350 will plot vectors from 0 to 1022.
A HP1351 will not. It will plot vectors from 0 to 1020.
I need to retest this up to 1021 to see exactly where the
limit is.
The program I'm using for this testing draws a box around
the limits of the display, and then two diagonal lines from corner
to corner. The result is a large box with an X through it.
When the 1351 'fails' to plot the box, only the left hand Y axis
vector is drawn. No letters appear.
When a 1350 tries to draw off the edge of the screen one
of two things happen.
Either a vector is drawn that wraps around, or a letter or
symbol is drawn in place of the out of bounds vector.
----- Original Message -----
From: "Tony Duell" <ard at p850ug1.demon.co.uk>
To: <cctalk at classiccmp.org>
Sent: Saturday, April 22, 2006 6:02 PM
Subject: Re: 1350A vs 1351A
I have both boxes attached to systems, I can try to test this.
I've looked at the HP1351 manual on hpmuseum.net, alas I didn't have my
1350 manual with me at the time...
The mechanical layont is identical, but as far as I can see the only PCB
that's the same is the backplane. But the general blocks of electronics
are much the same in the 2 devices. The RAMs, are of course differnt (the
1351 seems to use normal 4116-like 16K bit DRAMs, the 1350 uses those
TMS4096-like 22pin 4K bit DRAMs).
I have a few test patterns that were written for
the 1350 that do not
display correctly on the 1351 however (odd!). So am I sure that
there is a real difference in how they react when you plot past
the limits, whatever they are.
It's quite likely there's extra logic in the 1351 to prevent plotting to
a corodinate that would be interpretted as a text character.
-tony