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# ECB Color Video Display Unit

## Introduction

The ECB Color Video Display Unit board provides a color video terminal to RBC ECB bus systems using the MOS8563 chip found in the Commodore 128. Features include:

• MOS8563 display chip
• PS/2 Keyboard & Mouse inputs (note: only the keyboard input appears to have been tested based on past documentation)
• CGA (digital) output on pin header
• Resistor network DAC with EGA signal output on a VGA-style connector

## Hardware Documentation

Current Revision: Rev 2.00-007

Board: colorvdu2_board.pdf

Schematic: colorvdu2_schematic.pdf

Manufacturing Files: (not present on old wiki)

KiCAD Files: (not present on old wiki)

Archived files related to prototypes & Rev 1.00 boards can be found on the Color VDU Rev 1.00/Prototype Files page.

## Build Information

### Construction Notes

Construction Notes for the Color VDU 1.0 / 2.0

1.  CAUTION:  capacitor C15 on the PC layout looks like
any other decoupling cap; it is not!!!  It is 10pf.

2.  The DRAM chips are decoupled on the schematic using
0.22uf caps, about twice the value for the other de-
coupling caps.  Instead of C11 & C12, which decouple
the DRAM chips, the board layout requires that three
caps decouple the DRAM chips:  C6, C12, & C14.  Use the
higher value caps in these three locations.

3.  The resistor network used to convert the output of
the 8563 to VGA levels is highly experimental; THE VALUES
OF THESE RESISTORS MAY CHANGE.  I suggest putting a 14-pin
socket in the location for R21,R22,R23;R31,R32,R33,R34.
(See Note 9, below.  These values test okay.)

4.  The schematic from which this board was derived did
not specify a value for the inductor on the power supply
of the 16Mhz oscillator.  Choose one with low series
resistance.  1uh to 100uh would be my guess as to the
proper inductance.  One wants a high frequency choke to
isolate the board power supply from oscillator feedback.
(I hope the 8Mhz oscillator does not show up on the
video chip output.)

5.  For version 1.0 ONLY, there is a clearance issue between the
16Mhz oscillator and the nearby 74LS06 if a full-can oscillator
is used.  Either switch to a half-can oscillator or bend the pins
on the full-can oscillator slightly to avoid shorting pins 14,
13, and 12 of the 74LS06.  It would be good to insert an insulator
between the full-can and those pins.  This clearance problem was
corrected in version 2.0.

6.  For version 1.0 ONLY, circuit mods are requited to operate with
both the SBC v2 (Z80) and the SBC-188.  8563 pin 9 is changed from
/WR to RD. RD is generated through an LS04 from /RD output from the
LS244. [Pin 9 will have to be disconnected from the board by bending it
up and connecting directly to it.  The board surgery needed is
too extensive.  20-Feb] 8563 pin 4 is changed from A1 to the output from
an added LS00 gate, the inputs to which are /RD and /WR.  Hence, the 8563
will select only during /RD or /WR.  [Pin 4 may be disconnected from
the board by bending like pin 9, or by cutting the single trace
on the bottom of the board which connects to it.  20-Feb]
NO circuit mods are required for version 2.0.

7.  Test programs are posted for the SBC-188 as of this date.

8.  For version 1.0 ONLY, including Dan's comment:  U33 pins
2 & 3 must be changed from Vcc to GND.  It is practically impossible
to do the surgery on the board, so bend the 2 LS138 pins up and add a
jumper to GND (pin 7).  This change is NOT required on version 2.0.

9.  The resistor net which converts 8563 output to VGA levels
uses 820 ohm and 390 ohm resistors.  For input to a true
75 ohm VGA connector, these appear to be the correct values.
(Update to Note 3, above.)

10.  Notes 3 & 6 updated.

11.  For version 1.0 ONLY, the interrupt signal from the keyboard/mouse
is a positive signal, not an inverted signal (/INT).  Hence 74LS04 inverter
U21B should be omitted.  Bend pin 4 up to disconnect, and solder
a jumper from pin 3 to pin 4.  This change is NOT required for version 2.0.

--John Coffman
14-Jan-2012
23-Jan-2012
06-Feb-2012
20-Feb-2012
14-Dec-2012

--Wayne Warthen
07-Apr-2014

### Test Programs

Color VDU Test Programs for use with Z80 CPU boards such as the SBC V2 and Mark IV.

Color VDU-188 Test Programs for use with the SBC-188.

Please use this space to add any notes/comments on this board that don't fit into the above sections. (Periodically, these comments may be re-arranged to be better incorporated into a new revision of the wiki page.) Please sign your comments using the wiki “Insert Signature” feature! — Andrew Bingham 2016/02/27 13:01

Note: Some photos show prototype/Rev 1.00 cards.