The GDC-11 board is a highly integrated peripheral component designed for both
black-and-white and color graphics. The systematical architecture of
GDC-11 allows configuration of one, two, four or eight bit per pixel.
It can be enhanced by adding an analog board. The basic configuration is
very compact: it consists of a dual-slot Q-bus module directly connected 
to a monochrome or color monitor. 
The optional analog board is needed only if you would like to display
gray values or more than eight colors.

     High performance and great functionality of GDC-11 satisfy the 
application challenges even in the laboratory areas: data acquisition,
processing and displaying is now easily done by your PDP(r)-11 computer. The
GDC-11 board is fully DEC(r) Q-bus compatible. Containing 256K bytes of
graphics memory on board, GDC-11 requires only one slot in your backplane
and is connected via coax cable to a standard monitor. GDC-11 is
used especially in those application areas, where high standards of resolution
and performance are required, e.g. CAD/CAM and digital signal processing. 

The heart of GDC-11 is the NEC μPD7220A processor. It generates the
required video signals and modifies the graphics memory when executing
drawing operations. After receiving some drawing parameters
from the CPU, it performs the required calculations for the drawing process,
thus acting as an intelligent coprocessor and freeing
the CPU from number crunching. GDC-11 defines four registers
in the I/O-page of the PDP(r)-11 to communicate with the
CPU: control/status, parameter/data, zoom/color and DMA-data.

The following example demonstrates the high performance of GDC-11: to
connect any two points by a line, the CPU has to send the
coordinates of the starting point and four other parameters to GDC-11,
which are computed from the differences of the coordinates of the
two points. Provided a PDP(r)-11/23, a line length of 300 pixels results in a
drawing time of 1.7 milli seconds, flicker free and parallel
to the CPU activities. This test was programmed entirely using the high-level
language Modula-2. The Modula-2 statements you would use
to set the cursor to (x1,y1) and draw a line to (x2,y2) are:
Px := x1; Py := y1; draw(x2,y2). 
With a black-and-white GDC-11 module you can address
x-coordinates between 0 and 2047 and y-coordinates
between 0 and 1023. With a color GDC-11 version, the bit-map size is
0..1023 for x and 0..512 for y. To draw a line in color c, where c ranges
from 0..15 (4 bit/pixel) or 0..255 (8 bit/pixel)
you specify the drawing color using the statement
WriteColor(c). With the optional analog board GDC-11/L you can
define and change the color representation by modifying the color lookup-table.

Besides the GDC-11 versions for standard monitors: GDC-11/1,
GDC-11/4 and GDC-11/8,
there are three configurations for high resolution monitors:
GDC-11/1HR, GDC-11/4HR and GDC-11/8XC for 1, 4 and 8 bit per
pixel. HR means  h igh  r esolution, XC means e x tended  c olor.
For every system is excellent software available: a modular
graphics library GDC-11/S ( s oftware) for the programmer and
a graphics editor called SILcad. SILcad is a computer aided drafting
program well suited for
physicians and engineers. Constructional and electronical
plans can easily be drawn by using a mouse.

The monochrome GDC-11/1HR is ideal for displaying text, data and
technical drawings on a 17 Inch monitor using portrait format.
An optimal picture is gained from using black patterns on white
background combined with a special illuminant. The hcm44 monitor
series from AEG-Telefunken provides A-4 display format
with short persistance, bright, flicker
and glare free. Of course, you can use monitors from other
manufacturers. The graphics memory is organized as
2048 x 1024 pixels with a display resolution of 832 x 1024 pixels, video signal
bandwidth (= pixel rate) 70 MHz, horizontal frequency 64 KHz, vertical frequency
55 Hz, non interlaced. When using a small character set with a 8 x 12
matrix, you can display 85 lines, each containing 104 characters.

The eight-color version GDC-11/4HR suits CAD applications,
data display and business graphics. Graphics memory organization
is 1024 x 512, display resolution is 640 x 512 pixels in
1/50 second using an 14 Inch monitor with 32 KHz horizontal
frequency and 24 MHz pixel rate. Only three out of the four bits are
used for the RGB output. The fourth bit can be used
to set its corresponding pixel to white, independant of the other bits.

Maximum power is gained from the GDC-11/8XC color system. Eight bit
per pixel, 512K bytes graphics memory and two graphics processors
μPD7220A lead to the ultimate in computer graphics - you can fulfill
highest standards in material testing and medical image processing.
As with the GDC-11/4HR you get a 640 x 512 pixel display resolution, but now
having 256 colors or gray values
available for display. The GDC-11/8XC configuration
consists of two GDC-11/4HR and one analog board, together three
dual Q-bus boards. The boards are connected via a 24 wire ribbon
cable, the so-called  GDC-bus . The two GDC-11/4HR operate in master-slave
mode. Having 256 values per channel (three channels: RGB), you can
choose 256 colors out of a range of 2**24 possibilities.

The analog board GDC-11/L for the GDC-11/8 is a Q-bus module which 
has a GDC-bus interface. It communicates via a control/status register and
three data registers. GDC-11/L serves two functional requirements:

(1) transformation of the digital pixel information into an analog
output signal. This transformation is accomplished by means of a
(via I/O page) loadable color map (= color lookup table). The digital
information stored for each pixel is 8 bit, this gives 
256 different colors for each pixel. Since a color monitor has only
three different analog inputs, the color map transforms the value of
a pixel to one intensity value for each of the three signal outputs, again
with 8 bit resolution. The analog output is generated by three fast 
monolithic ECL- digital/analog converters. 
This process runs at the speed of the
pixel rate, i.e. 24 MHz. The colors are defined by loading the
color map with 256 out of 2**24 possible colors.
 Special feature:  you can use two vertical separated display areas
with a variable number of lines, each having 256 colors, i.e. you
can display 512 different colors at any one time in two separated areas.
This might be useful in displaying the same picture twice: one
picture using gray values, the other using pseudo colors. The
full capacity of the color map is 3*1024 bytes, providing 4 different
tables with 256 elements per display area and channel. Two tables define
the color or gray level set currently displayed for each area. Changing
a bit of the control/status register switches to the second color

(2) The second function is to split up the 8 bit value of
one pixel information into two 4 bit pixel values for the internal
format of the master/slave GDC-11 configuration. 
This transformation is done using two 16 bit data merge  registers 
with the purpose of speeding up the picture loading process.


  o Raster-scan graphics system for the DEC(r) Q-bus

  o Color graphics, gray levels  or black-and-white

  o Basic system built upon a dual slot card

  o Graphics memory: 256K bytes (32 * 64K bit dynamic RAM)

  o  GDC-11/type, graphics memory configurations and monitor type :

 GDC-11/1 : 1 bit/pixel * 2048 * 1024 pixels (dual-slot board) 
for standard 15 KHz b/w monitor

 GDC-11/1HR : 1 bit/pixel * 2048 * 1024 pixels (dual-slot board)
for 64 KHz b/w monitor

 GDC-11/4 : 4 bit/pixel * 1024 * 512 pixels (dual-slot board)
for 15 KHz RGB color monitor

 GDC-11/4HR : 4 bit/pixel * 1024 * 512 pixels (dual-slot board)
for 32 KHz RGB color monitor

 GDC-11/8 : 8 bit/pixel * 512 * 512 pixels (2 dual-slot boards incl. 
GDC-11/L, image processing only) for 15 KHz b/w monitor 
(256 gray values) or 15 KHz RGB color monitor

 GDC-11/8XC : 8 bit/pixel * 1024 * 512 pixels (3 dual-slot boards incl.
GDC-11/L) for 32 KHz RGB color monitor

  o Easy system integration and programming:
there is no Q-bus DMA and no interrupts, due to the powerful
graphics processor with its local buffer- and graphics memory. This 
means: (1) no problem for GDC-11 to run with every Q-bus (16, 18 or 22 bit) and
(2) simple device drivers for the operating systems

  o No color layer splitting, i.e. no
bit plane architecture. The graphics memory is not mapped into
the Q-Bus's address space, i.e. no dual port memory.

 Special feature :
the mask register architecture allowes quick drawing using all
colors together, i.e. (1) no speed slow down when using color instead of
black-and-white graphics and (2) high software portability;
application programs designed to run on a black-and-white graphic system
also run on a color system without modification.

  o Two independant display areas, vertical length freely
programmable: 0 <= v1 <= height; v2 := height - v1; height = 1024-1(b/w) or 

  o Host CPU is unburdened; parallel processing of CPU and GDC-11

  o Parallel processing of two GDC-11/4 in master/slave mode with

  o Bidirectional FIFO for commands, parameters, and data. 
FIFO capacity 16 bytes

  o Flicker free writing and reading of the graphics
memory using WDAT, DMAW and RDAT, DMAR commands

  o GDC-DMA-speed, for example loading of the display memory of
GDC-11/8XC using a 15 MHz LSI-11/73 with the 7220A-WDAT-command in
 non-flash  mode programmed entirely
in Modula-2 (without MACRO (assembly) tuning) lasts
5 seconds

  o Font software defineable (no on-board ROM), i.e. no restrictions
on font selection. Variable character height and width for proportional 
and/or fixed spacing fonts. Enlargement of fonts by writing zoom factor
(1 to 16).

  o On-board graphics processor NEC μPD7220A,  
up to 70 MHz pixel frequency 

o Video monitor parameter software loadable (front-porch, back-porch und 

o Generates vectors (up to 1.5 mega pixel/sec), rectangles and arcs

o Drawing process' operating modes: set, replace, complement or erase pixel
(Paint Mode)

o Hardware display zoom: factor 1 to 16

o 8 directions and writing zoom factor 1 to 16 for
graphic patterns

o Drawing with 45 Grad  increment, with or without slanting

o Area filling with any 8*8 pattern

o Panning: displaying one or two windows. Variable
starting line and horizontal offset within the whole graphics memory

o Non-interlaced/interlaced-mode: switched by software


  o Video output: BAS-signal, RGB and/or TTL-signals, H/V-sync-signals
separately (Lemo- connectors)

  o Video norm: programmable video raster parameters and monitor format 
(number of lines: active lines, pixels per line: active words) 

  o Optional external synchronisation

  o Q-Bus: load 2 A typ. at +5V (+/- 5%)

  o GDC-11/S*: GDC-11 SOFTWARE  

o Sophisticated utilities: mouse controlled
graphics editor SILcad and multi- file/multi- window text
editor EDIT86, as well as
modular graphics libraries for Modula-2 and other languages.

o SILcad graphics editor for the interactive design and manipulation
of line drawings using a 3-buttons mouse (Souris P-4).

 Features :
Drawing, moving, copying, (color dependant) selection, reducing,
enlarging, mirroring, changing of color, character set and grid,
rubber band moving, saving and retrieving of graphical objects.
Graphical objects are horizontal and vertical lines of various
width, as well as vectors, circles, macros,
texts consisting of different fonts and
heights. The drawing plane
consists of 2048 lines, each having 1664 pixels on GDC-11/1HR.
You can hardcopy to matrix-, ink-jet-, laser- printer or plotter.
See SILcad V5.6 product description.

SILcad is the PDP-11/GDC-11 portation of Lilith's graphics
editor SIL V5 with several extensions. The author of the original version
is Niklaus Wirth from Institut für Informatik at ETH-Zürich.

o EDIT86 text editor.

 Features :
multiple documents: eight text files can be edited at the same time,
multiple windows (views) per document at the same time,
open/close window or document, change the size of a window,
(currently) up to 127 blocks per file,
mouse/pull-down menu controlled cursor/caret position and command selection,
full  replay  after recovering from power-, hardware-, disk-,
software- failure, interactive replay control stop- continue- terminate,
text selection, deleting, copying and moving with mouse,
unlimited save/cut/paste buffer,
moving/copying text from one window/document to another,
relative and absolute positioning: flipping and scrolling,
ASCII character set 8*12 fixed-width font & extended character set (umlaute),
auto- indentation, programmable user profile and guidance,
learn mode/execute macro, supports 8-bit control characters.
Besides a title line and two lines for the dialog window there are
60 lines à 100 characters (GDC-11/1HR portrait A-4 format) or
30 lines à 80 characters (GDC-11/4HR landscape format).

EDIT86 is the PDP-11/GDC-11 portation of Lilith's Editor VC1.2 developed
at ETH-Zürich. The authors of the original version are 
Jürg Gutknecht, Christian Vetterli, Werner Winiger and Niklaus Wirth from
Institut für Informatik at ETH-Zürich.

o For Modula-2 programmers: the modular graphics library includes
the modules Cursor Mouse, Menu, Windows,
Text Windows, Graphic Windows as defined in the appendix of N. Wirth's book, 
"Programming in Modula-2", Springer- Verlag, Heidelberg - New York,
1985 (3rd Edition).

o  Extensions :
proportional spacing, colors (8 or 256), WritingZoom- and Panning-feature.
You also get the following procedures:
DefineArea, Zoom, Pattern, Mask, WriteColor, DisplayColor,
LoadColor Map, MergeData, ReadData, WriteData,
as well as MapChar for the extended ASCII character set.

o  Fonts : 
any pattern within a 16*16 matrix. Currently seven different fonts
are available.

o Writing of single characters to various positions, for
example in Modula-2: Px:=x; Py:=y; Write(ch), 
prints character ch at position (x,y). Every character of a font
has its individual character width. Fonts are loaded dynamically.
You can freely combine different fonts and sizes at any one time. Change the
actual font? No problem in Modula-2: Load Font ('DK small GDC', ok).
Each font file, e.g. DK:SMALL.GDC, consists of 9 blocks and defines
an extended ASCII character set (ECS) containing 128 characters.

o GM.SYS graphics memory
device handler (read/write, file structured, 512 blocks, bootable) for RT-11 

o For PASCAL/FORTRAN/MACRO programmers: the subroutine package
GDCLIB.MAC (commented sources provided) contains the following
functions: MOVE (X,Y), DRAW (X,Y), 
LINE TYPE (pattern), PAINT COLOR (color), DISPCOLOR (color),
(dx,dy,dir), CIRCLE DRAW (radius), AREA FILL (dx, dy, dir),
PRAM (gchr), WRZOOM (factor), PITCH (xlength), PAN (x,Y), ZOOM (factor).
Pattern is a 16 bit pattern for the drawing of vectors, circles and so
on; mode is one out of the paint modes (add, erase, replace, invert).
Also included: video parameter initialisation program GDCINI.FOR to be executed
at system startup and
application example GDCTST.FOR for the GDCLIB.

o Software is distributed
on 8" floppy disk RX01/RX02 format,  RT-11 file structured. RX50 on request.

   GDC-11 HIGH LIGHTS (All GDC products made in West Germany):


Exclusively manufactured using high quality components, DEC(r) LSI-bus 
specification with interface chip-kit from DEC(r),
gilded bus contacts, fast Schottky building parts, 32 bit shift register
output, up to 70 MHz pixelrate with high resolution version,
high integration using 3 PALs (programmable array logic), fast data
transfer with GDC-DMA mode. GDC-11 can act as a (bootable) RAM disk with GM.SYS
under RT-11. You have 512 blocks (256K bytes) of virtual graphics 
memory per GDC-11 available, also when using processors without MMU, for 
example LSI-11/2. The reason is the graphics memory being not accessed
directly via Q-bus, but via I/O page and manipulated by the graphics processor
μPD7220A. We guarantee second source for all building parts. The
cards have burn-in, the circuit scheme is available on confidential base.


State of the art software technology, modular design, programming
language Modula-2, FORTRAN or MACRO, less than 4K bytes for XY graphics
library, efficient and easy to program, storing drawing command
sequences or drawings on any mass storage device, Window Handler for text and
graphics, cursor positioning and pull-down menu selection by mouse.
The system and application software runs on all
types of the GDC-11 series without modification.


The illustration on "GDC-11 Configurations" on next page was drawn
on a PDP-11 under RT-11
using a three-buttons mouse, a GDC-11/1HR and SILcad software.
The drawing requires 12 blocks (6K bytes) of mass storage. It
consists of 560 line- and text- elements (including a scaled copy of itself
in the 17 Inch monitor). 
To rebuild (repaint) the whole drawing an LSI-11/23 CPU needs 5.5
seconds. The hardcopy raster is 640 * 864
on an A-4 sheet (8"*12") using a low-cost matrix printer Speedy 100-80.

(R) DEC, PDP, VAX are registered trademarks of Digital Equipment Corporation

(C) (1983) by Günter Dotzel. 

Specification, update, layout, printing: 12/1985, ModulaWare, Erlangen.