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DT003 SimmStick Motherboard
Features
- SimmStick Bus Power Supply
- Communications Port using a Max-232 and DB9
- Four slot SimmStick Bus and bus extender
- Double sided, plated through, solder masked, silk screened 1.2mm PCB
DT003 is a motherboard, not a programmer. It's an ideal end-user platform for chips that have already been programmed such as FED, Parallax, or any other Basic Interpreter chips, or any SimmStick that requires just a power supply or a comms port and a small SimmStick bus structure.
The DT003 is like a short DT001 (2.675" long, same width) with a power supply, D-9 connector, MAX232, reset and boot buttons, 4 SIMM sockets, and expansion connector on the right hand end, same as DT001. Because it's a simpler board - it's much cheaper.
Assembly
Component Overlay
DT003 Parts List
1 by DT003 PCB 1 x 7805 +5 Voltage regulator in TO-220 case. 1 x Suitable heat sink for above Regulator. 1 x Diode Bridge D1 WO2 (or WO4 type) 1 x 2.1mm (or 2.5mm) DC Input plug. PCB mount. You can use screw terminals with .2" centers.
1 x Capacitor C1 1000uf Electrolytic @25 Volts. (PCB type mount.)
You can also use larger caps. These can have 0.3", .4", or .5" centers, or 1000uf, 2200uf or 4700uf, but you may have difficulties with the larger diameter capacitor (4,700uf) if you require the comms components. In most cases, the 1000uF cap is fine.
1 x Capacitor C2 .01uf (or .1uf) Ceramic 1 x Capacitor C3 .01uf (or .1uf) Ceramic 1 x Capacitor C4 10uf Electro/Tant 16 V-PCB mount 1 x Resistor R1 330 .25 watt Green LED 1 (+5V) 1 x 5mm Red LED. LED 1 +5V monitor 4 x stick-on rubber feet add a nice finish.
Parts for Serial Communications
Caps (C5-C8) are Electrolytic/Tant @16V PCB mount. 1 x Capacitor C5 1uf 1 x Capacitor C6 1uf 1 x Capacitor C7 1uf 1 x Capacitor C8 1uf 1 x MAX-232 E2 (or equivalent) 1 x D-9 right angle PCB mount connector.
It may also pay to install a 16 pin socket for the Max-232, as you may have to remove it for some configurations.
The unused pins of the Max-232 have been brought out to pads. The RS-232 signal level pads can be found near the D-9 connector pins on the solder side of the board. The TTL levels are found at header J1. Pin 1 is input, and pin 2 output.
RESET and BOOT Switches
The Reset switch can be added for CPU control, as can the BOOT switch on the SDA line. If a pull-up resistor is fitted on a SimmStick module, this line can be used as a switch input. It can also be used for FED Basic COMMS control.
1 x Resistor R2 330 .25 watt Boot Button. 1 x Resistor R3 330 .25 watt Reset Button. 2 x Suitable switches.
These can be the pretty plastic color ones that have .2" centers, or the mini 4 pin TACT switches that have a .2" by 0.3" pattern.
SimmStick Bus Extender
J2 is shown as a 30 pin female right angle header.
This can be used to extend the SimmStick bus to other boards.