[[boards:ecb:scg:start]]
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boards:ecb:scg:start [2018/08/13 09:02]
b1ackmai1er [Board Configuration] 		boards:ecb:scg:start [2019/01/09 09:05]
b1ackmai1er [Board Construction]
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 For information on prior board versions, see the [[https://retrobrewcomputers.org/n8vem-pbwiki-archive/0/35845334/48860720/33053543/index.htm|Legacy Wiki SCG Folder]]. For information on prior board versions, see the [[https://retrobrewcomputers.org/n8vem-pbwiki-archive/0/35845334/48860720/33053543/index.htm|Legacy Wiki SCG Folder]].
 +
 +===== Acknowledgments =====
 +
 +The ECB-SCG was developed by <font 10.0pt/Arial;;inherit;;inherit>Tom LeMense and Dan Werner.</font>
  
  
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 {{:boards:ecb:scg:scg-002-bom.xlsx|Parts List - XLS}} {{:boards:ecb:scg:scg-002-bom.xlsx|Parts List - XLS}}
  
-The TMS9918 is an NTSC format chip. A PAL version of this chip is available (TMS9928A) but it is not known if it is compatible.+The TMS9918 is an NTSC format chip. A PAL version of this chip is available (TMS9928A) but it is not totally compatible per the following from the datasheet. 
 + 
 +"The TMS9928A/9929A VDP's are functionally identical to the TMS9918A except that the NTSC color encoding circuitry has been removed and replaced with luminance and color difference signals. The TMS9918A is pin-for pin compatible with the TMS9928A/9929A, except for three pins, the composite video output, the external video input and the CPU clock output. These pins are replaced with the Black,White luminance and composite sync (Y) output and two color difference pins, Blue (B-Y), and Red (R-Y) outputs, respectively. The color difference outputs allow the user to generate Red-Green-Blue (R-G-B) drive for direct color gun control, or composite video for use with NTSC or PAL video color monitor. However, to connect these three outputs to R-G-B or monitor requires additional R-G-B or encoder circuity" 
 + 
 +So maybe that is something for the next iteration…
  
 A 2Mhz crystal is specified for the sound chip clock but on board dividers can be configured to use a higher frequency crystal. Also common serial and colour burst frequency crystals can be used depending on your need for frequency accuracy and compatibility. A 2Mhz crystal is specified for the sound chip clock but on board dividers can be configured to use a higher frequency crystal. Also common serial and colour burst frequency crystals can be used depending on your need for frequency accuracy and compatibility.
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   * Earlier runs of this board required a patch for sound to work. This patch is documented in the [[https://retrobrewcomputers.org/n8vem-pbwiki-archive/0/35845334/48860720/33053543/index.htm|Legacy Wiki SCG Folder]].   * Earlier runs of this board required a patch for sound to work. This patch is documented in the [[https://retrobrewcomputers.org/n8vem-pbwiki-archive/0/35845334/48860720/33053543/index.htm|Legacy Wiki SCG Folder]].
   * Install **either**  Q3 **or**  P2, but not both. These are mutually exclusive options for the video amplifier circuit.   * Install **either**  Q3 **or**  P2, but not both. These are mutually exclusive options for the video amplifier circuit.
-  * Crystal X2 **must**  be parallel resonant. +  * Crystal X2 **must**  be parallel resonant. Installation of a series resonant crystal will result in the video controller chip running at the wrong frequency and colours may not be displayed correctly. 
-  * The TMS9918 video controller is sensitive to CPU clock speeds. In general, I have found all software posted here to function well at 4MHz. Higher CPU speeds may or may not work.+  * The TMS9918 video controller is sensitive to CPU clock speeds. In general, I have found all software posted here to function well at 4MHz. Higher CPU speeds may or may not work. It is normal for the TMS9918 chip to run quite hot.
   * Joystick interface is digital. The up, down, left, right, and button switches should be normally open and shorted to ground to activate. An Atari 2600 joystick can be readily adapted. PC-style game controllers use potentiometers for up/down and left/right and are therefore **not**  appropriate.   * Joystick interface is digital. The up, down, left, right, and button switches should be normally open and shorted to ground to activate. An Atari 2600 joystick can be readily adapted. PC-style game controllers use potentiometers for up/down and left/right and are therefore **not**  appropriate.
 +
  
 ==== Errata ==== ==== Errata ====
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 **JP1: TEST2 Enable** **JP1: TEST2 Enable**
  
-Shorting 1-2 will ground the TEST2 pin of the sound controller, otherwise the pin will be disconnected. You would normally leave this jumper open. Refer to AY-3-8910 datasheet.+Shorting 1-2 will ground the TEST2 pin of the sound controller, otherwise the pin will be disconnected. You would normally leave this jumper open. The AY-3-8910 datasheet does not document the functionality of the test configuration.
  
 **J21: Interrupt Enable** **J21: Interrupt Enable**
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 **RV9: Right Channel Audio Output Volume** **RV9: Right Channel Audio Output Volume**
  
-<note>The Left channel and Right channel trimpot are wired in reverse direction and will be required to be set at different positions for balanced sound levels.</note>+<note>The left channel and right channel trimpot's are wired in reverse direction and will need to be set at different positions for equal sound levels on each channel.</note>
  
  
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 The SCG board is not intended to be a general purpose terminal controller like the VDU, CVDU, and VGA3 boards. It does not have a keyboard interface and text output is limited to 40 characters per row. So, the typical way to use the board would be to add it to an existing system already running CP/M (RomWBW, UNA, etc.) and then run programs that utilize the graphics and sounds capabilities of the board. The MSX games and programs described below do exactly this. You start your system in normal CP/M, then run the MSX game/program desired. The SCG board is not intended to be a general purpose terminal controller like the VDU, CVDU, and VGA3 boards. It does not have a keyboard interface and text output is limited to 40 characters per row. So, the typical way to use the board would be to add it to an existing system already running CP/M (RomWBW, UNA, etc.) and then run programs that utilize the graphics and sounds capabilities of the board. The MSX games and programs described below do exactly this. You start your system in normal CP/M, then run the MSX game/program desired.
  
-Note that RomWBW (v2.8.5 and above) does provide support for text output to this board (assuming you have enabled TMS support). The board is accessed as the CRT device, so sending output to CRT: will work. However, it is not possible to read from the CRT: device because the board has no text input capability. It is **not**  necessary to have the TMS driver enabled in RomWBW to launch the MSX software – the MSX emulator below includes it's own driver for the board.+RomWBW (v2.8.5+) provides support for text output to this board when TMS support is enabled. The board is accessed as the CRT device, so sending output to CRT: will work. 
 + 
 +<code> 
 +B>PIP CRT:=A:TEXTFILE.TXT 
 +</code> 
 + 
 +It is not possible to read from the CRT: device because the board has no text input capability. It is **not** necessary to have the TMS driver enabled in RomWBW to launch the MSX software – the MSX emulator below includes it's own driver for the board. 
 + 
 + 
 +==== Test Software ==== 
 + 
 +Two programs are available to test basic video operation of the card in the {{:boards:ecb:scg:tms9918-test.zip|tms9918-test}}  package. Refer to images below. 
 + 
 +HW9918.COM will display the "HELLO WORLD" text on the screen. 
 + 
 +TSTSPR.COM will display sprites and allow background colour changes. 
 + 
 +Sound functionality can be tested with the {{:boards:ecb:scg:ay-test.zip|ay-test}}  package. 
 + 
 +AY-TEST.COM will output a descending tone to each sound channel. 
  
 ==== MSX Programs ==== ==== MSX Programs ====
boards/ecb/scg/start.txt · Last modified: 2021/11/29 08:45 by b1ackmai1er
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