1.General The Nukeman is a portable, battery powered computer with inherent SCSI-2, Ethernet, 2xRS232 interfaces and 6 Nukebus slots. It is notebook sized (260 x 240 x 78 mm, almost half of this space occupied by the slots), has a 75 Wh NiMh battery inside and weighs (including battery) 3.4 kg. The computer is 68340 processor based and is running DPS, our multi-task operating system. The Ethernet interface employs a DP83932 (SONIC) chip; the SCSI interface uses an NCR53CF96 which supports SCSI-2, and the 2 RS-232 ports use the internal UART modules of the 68340. The keyboard is external only; the input expects a standard serial keyboard. The battery and the DC-DC convertors are controlled by a 68HC11 MCU which communicates with the main processor via the SPI interface (with ID no.7; slots are 0 to 5). The MCU monitors the +5,+15,-15,+24 and -24 volt outputs and detects short circuit, overload and overvoltage at each of them individually;the convertor associated with the event is shut down. Status information is available to the main processor, as well as other unit unique data (like serial number, system clock frequency etc.). Battery charge/discharge is done under MCU control; there are various battery associated parameters available for modification. The MCU is never switched off, during power-off it is only 32 kHz clocked, and continues to operate as real-time clock and power-on key monitor. Once the power is on, the MCU is clocked at full speed, powers the computer with the 68340 and continues in a more sophisticated board monitor/interface mode. The 68340 computer boots DPS either from the default device (the internal HDD) or, if the proper key was held down during power on, enters the ROM monitor program from where it can be commanded to boot from any SCSI and/or IDE device.
2. Nukebus general description. Nukebus was designed in order to define one more layer between the user operated computer and the acquisition/control hardware. Standard PC interfaces in most cases lack some of the power supply voltages necessary, impose compatibility problems, and become less and less the suitable choice for hardware control as processors become bigger and more pipelined. Nukebus is not meant to be a memory expansion bus. The basic type of device, which would be connected to it, is a module (usually with its own single-chip microcontroller) used for measurement and/or control functions, which needs either slow or fast or both data transfers to/from the host computer. The fast data transfers are done through the 16 data lines; every slot is addressed by a pre-decoded address strobe signal, and has 8 address lines available for internal addressing. Several interrupt request/acknowledge lines are also available. The slow data exchange is done via the 4 SPI lines. The Nukebus host computer selects one of the slots and clocks the data to/from the slot; this is the way the object type "nukebus_module" does get status data or sends commands to the module MCUs of the modules available from us. The power supply voltages at a Nukebus connector are +15, -15, +24, -24, +5 and Vbatt. Vbatt is the unregulated battery voltage (not specified as a value). There are 3 different ground signals : AGND (analog ground), DGND (digital ground) and PGND (power ground, the corresponding return of Vbatt only). The Nukebus connector is a 68-pin, 1.27 mm pitch connector.
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