BIG ol tektronix scope 555 - need it gone - make an offer

[Paul Koning]

> On Dec 11, 2018, at 7:59 AM, Toby Thain via cctalk <cctalk at classiccmp.org> wrote:
> 
> On 2018-12-11 1:17 AM, devin davison via cctalk wrote:
>> The line about being used with an early computer as a display caught my
>> eye. How would it be used as a display, what kind of graphics capability
>> would it have? is there an interface for the thing for the pdp 11 or a
>> modcomp? Those are the old systems i have on hand that i might be able to
>> interface to it.
> 
> A scope is at heart an electrostatic CRT with X and Y deflection (and
> perhaps Z axis blanking control). Many older systems did have such
> displays -- the PDP-1 is a well known example (e.g. see Marc and Lyle's
> CHM demo on YT[1]). Imlac PDS-1 is another. And before _digital_
> systems, scopes or X-Y displays were a typical output medium for
> _analog_ computers.
> 
> For digital computers, output is point plotting, vector drawing, and/or
> character generation depending on the sophistication (= cost) of the
> hardware involved. You'd also need to find or write suitable software :)
> 
> Yes, there were interface cards for PDP-11, such as AA11 (dual DACs).

I made such a setup in college: we had an 11/20 with AA11 (and other lab I/O gear).  I hooked those up to the X/Y inputs of a scope, and a digital I/O line to the Z input.  Then loaded coordinate pairs into a buffer on the RC11 disk, which was set up to do DMA directly to the AA11 data CSR.  Worked nicely, and with low overhead on a  machine that certainly could not afford to do refresh in software.

The classic example of a computer display like that is the CDC 6000 mainframe console.  That is essentially a pair of oversized oscilloscopes (with electrostatic deflection), with their X/Y inputs driven by a dedicated display controller that includes a vector character generator.

	paul