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boards:ecb:cvdu:start [2016/07/06 13:53]
admin [Construction Notes]
boards:ecb:cvdu:start [2016/07/06 19:36] (current)
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 ====== ECB Color Video Display Unit ====== ====== ECB Color Video Display Unit ======
 +{{:​boards:​ecb:​cvdu:​photos:​cvdu2_assembled.jpg?​nolink&​640|}} 
 +{{:​boards:​ecb:​cvdu:​photos:​img_1595-ega_no_dram_refresh.jpg?​nolink&​640|}}
 ===== Introduction ===== ===== 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: 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:
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 {{:​boards:​ecb:​cvdu:​colorvdu2.lst|KiCAD eeschema Parts List}} {{:​boards:​ecb:​cvdu:​colorvdu2.lst|KiCAD eeschema Parts List}}
  
-==== Construction Notes ==== +==== Construction Notes for the Color VDU Rev 1.00 / 2.00 ==== 
-<​file>​ +**Rev 2.00 board builders ​Notes 1, 2, 3/9, 4, 7 apply to your boards**
-Construction Notes for the Color VDU 1./ 2.+
- +
- +
-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.) +
- +
-Added 23-Jan-2012:​ +
- +
-5.  For version ​1.0 ONLYthere 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. +
- +
-Added 06-Feb-2012 +
- +
-6.  For version 1.0 ONLYcircuit 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 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 gatethe inputs to which are /RD and /WR.  Hence, the 8563 +
-will select only during /RD or /WR.  [Pin may be disconnected from +
-the board by bending like pin 9or 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. +
- +
-Added 20-Feb-2012 +
- +
-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. +
- +
-Added 14-Dec-2012 +
- +
-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 +''​1. ​ CAUTION: ​ capacitor C15 on the PC layout looks like any other decoupling cap; it is not!!! ​ It is 10pf.\\ 
-14-Jan-2012 +\\ 
-23-Jan-2012 +2.  The DRAM chips are decoupled on the schematic using0.22uf caps, about twice the value for the other decoupling 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.\\ 
-06-Feb-2012 +\\ 
-20-Feb-2012 +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.)\\ 
-14-Dec-2012+\\ 
 +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.)\\ 
 +\\ 
 +Added 23-Jan-2012:​\\ 
 +\\ 
 +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.\\ 
 +\\ 
 +Added 06-Feb-2012\\ 
 +\\ 
 +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.\\ 
 +\\ 
 +Added 20-Feb-2012\\ 
 +\\ 
 +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.\\ 
 +\\ 
 +Added 14-Dec-2012\\ 
 +\\ 
 +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''​
  
---Wayne Warthen 
-07-Apr-2014 
-</​file>​ 
  
  
boards/ecb/cvdu/start.1467827605.txt.gz · Last modified: 2016/07/06 13:53 by admin
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