11 Dec
2018
11 Dec
'18
6:15 a.m.
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:
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
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).