1350A vs 1351A

Bob Shannon bshannon at tiac.net
Sun Apr 23 21:47:29 CDT 2006

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

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