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The digital signals for ports 19H through 1CH in and out are two's complement representations of the bipolar analog signals associated with each port. The analog voltages are -2.5 to +2.5 volt range for the inputs (DC coupled) and -2 to +2 volts for the outputs (AC coupled). The negative limit is 80H, midrange (0V) is 00H, and the positive limit is 7FH.
The maximum analog input voltage which should be applied to the ADC inputs is +/- 5 volts. The ADC inputs are high impedance, and the DAC analog outputs are from a 1K ohm source with filtering to restrict the bandwidth to the 100Hz to 4 KHz range with a 10K ohm load. A PWM DAC operating at 40 KHz is used for the analog outputs.Joystick pinout on J11 and J16: Pin Signal 1 SW1 (top) Low if pressed, JS1 = port 18H in bit 0, JS2 = port 18H in bit 4, H is +5V from 10K source 2 SW2 Low if pressed, JS1 = port 18H in bit 1, JS2 = port 18H in bit 5, H is +5V from 10K source 3 SW3 Low if pressed, JS1 = port 18H in bit 2, JS2 = port 18H in bit 6, H is +5V from 10K source 4 SW4 (bottom) Low if pressed, JS1 = port 18H in bit 3, JS2 = port 18H in bit 7, H is +5V from 10K source 5 +5V from TV Dazzler regulator, used by speaker drive amplifier and JS power converters if present 6, 8, 10 Analog ground for joystick X and Y outputs and audio input 7 Joystick X output +/-4V maximum with Parallax 27800 control and standard resistors 9 Joystick Y output +/-4V maximum with Parallax 27800 control and standard resistors 11 Audio signal +/-2V to speaker amplifier input, joystick box load on signal source is 20K ohms 12 Ground return for +5V power used by speaker amplifier 13 +16V from main bus for regulator in joystick box 14, 16 No connection on TV Dazzler 15 -16V from main bus for regulator in joystick box
The Parallax 27800 joysticks have a mechanical limit which restricts the movement to a circular pattern. For this reason they are scaled to give a +/-4V maximum output so it is possible to reach the corners such as +2.5,+2.5. Other joystick units may not have this restriction, in which case it may be desirable to change the resistors R8 and R14 in the joystick circuit from 100K to 15K ohm, giving a +/-2.7 volt maximum output. This will produce better resolution for the controls.In addition to the above original control ports there are several functions controlled by jumpers located on the PC board.
Video output connection J2: This connector is pinned out to work correctly with a standard VGA display.pin signal 1 Red, Pr, or composite video from a 75 ohm source. 0.7V P-P into 75 ohm load with 0.3V negative sync when used. 2 Green, Y, or composite video from a 75 ohm source. 0.7V P-P into 75 ohm load with 0.3V negative sync when used. 3 Blue, Pb, or composite video from a 75 ohm source. 0.7V P-P into 75 ohm load with 0.3V negative sync when used. 6 Ground return for pin 1 for coax. 7 Ground return for pin 2 for coax. 8 Ground return for pin 3 for coax. 5, 10 Ground returns for pins 13 & 14. 13 H sync from a 75 ohm source. +4V baseline open circuit, 0V negative going sync pulses normally. 14 V sync from a 75 ohm source. +4V baseline open circuit, 0V negative going sync pulses normally. H and V sync pulses may be made positive going by putting a jumper on P18 pin 29-30.
When the TV Dazzler is outputting B/W video (mode 0 0), pins 1, 2, and 3 are independent copies of the same video signal, and composite sync may be put on all three outputs by installing jumper P18 pins 27-28. If this jumper is not present, then only the output on J2 pin 2 will have composite sync.
When the TV Dazzler is outputting RGB video (mode 0 0), the sync waveforms are at standard TV rate and are present only on the G output unless a jumper is placed on P18 pins 27-28. The H and V sync outputs may optionally be used by the display if desired.
When the TV Dazzler is outputting RGB video for a VGA display (mode 1 0), the RGB outputs are 0.7 V P-P and do not have any sync. The display uses negative going sync from the H and V outputs.
When the TV Dazzler is outputting YPbPr video (mode 0 1), the Y signal will have composite negative going sync on it. The Pb and Pr signals, being bipolar, will have a 0.65 volt DC baseline offset into a 75 ohm load. This works satisfactorily on most component displays.
When the TV Dazzler is outputting composite video (mode 1 1), then composite sync, burst, and chroma are present on pins 1, 2, & 3. All 3 signals are independent copies of the same video and 1.0V P-P into 75 ohms.All modes use 59.94 Hz rate for vertical sync. VGA uses 31.469 KHz rate for horizontal sync, and all other modes use 15.734 KHz rate for horizontal sync. The color subcarrier is 3.579545 KHz, giving NTSC operation.
When the joystick board is build as shown above, it fits in the small Hammond 1590BB die cast box from DigiKey. This design has the virtue that there is no wiring inside the box. All connections are done by the PC board. However, there are several problems with this design: 1) The pushbuttons shown are easily damaged by side forces, and alternatives have a small button which causes finger soreness with extended use. 2) The joystick, although inexpensive, small and easy to obtain, has some undesirable features in its mechanical 'feel' and electrical zero dead zone. 3) The miniature speaker is inefficient even when given 0.2 watt of audio power.
The above problems can all be alleviated by using the circuit board as an interface tool and mounting it in a larger box, wired to better buttons and joystick, and a standard type 3 or 4 inch speaker. The disadvantage is the additional cost of the improved components is substantial.Adjustment of Joystick Pot
|P18 Jumpers:-||pin 35-36||pin 33-34|
|RGB Comp Video||no jumper||no jumper|
|Standard VGA||no jumper||jumper|
|Component Video||jumper||no jumper|
|Program Name||Runs under COM||Comments||Documentation|
|KSCOPE CPM.ZIP||Yes, with BDOS Print Signon||Displays continuous color patterns on screen|
|KSCOPE_100H.zip||Yes.||Runs immediately at 100H in RAM, no signon etc.|
|ADCTEST.ZIP||Runs under CPM||Used to test Joystick circuit.||Instructions are shown on CPM screen|
|SKETCH.ZIP||Yes, with BDOS Signon||Displays test pattern of lines on screen with joystick||See source code|
|SOUND.ZIP||Yes||Joystick buttons emit different sounds||Instructions on CPM screen|
|ADDRESS.ZIP||Yes with BDOS signon||Internal test of CPLD code. Draws "X" lines on screen||Info is shown on CPM screen|
|X-Life.zip||Yes.||Runs immediately at 100H in RAM. Works best if screen is first cleared. No signon etc.||Dazzler Games Manual|
|DOGFIGHT.ZIP||Yes.||Runs immediately at 100H in RAM. Works best if screen is first cleared. No signon etc. Requires Joystick Inputs.||Dazzler Games Manual|
|DAZCHESS.ZIP||Yes.||Runs immediately at 100H in RAM. Keyboard Input||Microchess Manual|
|COLOR.ZIP||Yes||Shows range of colors available on Dazzler II||Instructions are shown on CPM screen|
|SPACEWAR.ZIP||Yes.||Requires Joystick Inputs. No Source code, runs too fast with 10MHz Z80.||Dazzler Games Manual|
|Dazzler Graphics Instruction Manual|
|Dazzler Games Manual|
|Dazzler Spacewar Manual|
|Cromemco Software Database|
This page was last modified on 02/03/2017