3002

3002 is the ND-100 CPU board. It contains the CPU, bus arbitration logic, memory control and other subsystems. It also has the Real time clock and the I/O for the serial console.

There are schematics of the CPU in the.

Switches and indicators
As seen from the top, when the card is in the card crate (components on the right hand side). console speed thumbwheel switch ALD thumbwheel switch

Console speed setting Setting 14 and 15 is not defined (not used?).
 * 0 - 110 baud
 * 1 - 150 baud
 * 2 - 300 baud
 * 3 - 2400 baud
 * 4 - 1200 baud
 * 5 - 1800 baud
 * 6 - 4800 baud
 * 7 - 9600 baud
 * 8 - 2400 baud
 * 9 - 600 baud
 * 10 - 200 baud
 * 11 - 134.5 baud
 * 12 -  75 baud
 * 13 -  50 baud

Description of MOPC
MOPC is the name of the Microprogrammed OPerators Communication, a program stored in the micro code of the CPU. It can be used for low level testing of the hardware. Whenever the MOPC is active it is communicating via the console connected to the current loop connection on the CPU card. MOPC contains functions for examination of the memory, dumping registers, changing content in registers or memory, controlling breakpoints, bootstrap loading and other things.

I/O devices on the CPU board
The CPU board is equipped with two I/O devices, the real time clock and the system console.

RTC
RTC is the Real-Time Clock. It is a system that could generate interrupts on a 20 ms basis.

RTC IOX register map

 * IOX 10
 * Returns 0 in A register, no other effect.


 * IOX 11
 * Clears real time counter. This instruction will cause the next clock pulse to occur exactly 20 ms later.
 * If executed often enough it will stop the real-time counter from incrementing. This could affect operators communicating via the console.


 * IOX 12
 * Read real-time clock status.
 * Bit 0=1 : An interrupt will be generated at the next clock pulse.
 * Bit 3=1 : A clock pulse has occurred.
 * Bit 1-2 and 4-15 is always zero.


 * IOX 13
 * Set real-time clock status.
 * Bit 0=1 : Enable interrupt on next clock pulse.
 * Bit 13=1 : Set bit 3 to zero in the real-time clock status word.

Console
The console could be disabled by removing a strap.

Console IOX register map

 * IOX 300
 * Read input data (according to input control word setting). The last character is transferred to the A register. The data available signal is reset if MOPC is not active.


 * IOX 301
 * No operation.


 * IOX 302
 * Read input status
 * Bit 0=1 : Interrupt on "Data available" enabled.
 * Bit 3=1 : Data available. (Never set when MOPC is active.)
 * Bit 4=1 :
 * Bit 5=1 :
 * Bit 6=1 :
 * Bit 7=1 :


 * IOX 303
 * Set input control
 * Bit 0=1 : Enable interrupt on "Data available".
 * Bit 11=0, bit 12=0 : 8 bit data.
 * Bit 11=1, bit 12=0 : 7 bit data.
 * Bit 11=0, bit 12=1 : 6 bit data.
 * Bit 11=1, bit 12=1 : 5 bit data.
 * Bit 13=0 : 2 stop bits (1.5 stop bits for 5 bit data).
 * Bit 13=1 : 1 stop bit.
 * Bit 14=0 : No parity.
 * Bit 14=1 : Parity bit added to data.


 * IOX 304
 * Returns 0 in A register, no other effect.


 * IOX 305
 * Write output data (according to input control word setting).


 * IOX 306
 * Read output status.
 * Bit 0=1 : Interrupt on "Ready for transfer" is enabled.
 * Bit 3=1 : Ready for transfer.
 * Bit 1-2 and 4-5 are always zero (should probable be 1-2 and 4-15, an error in the documentation).


 * IOX 307
 * Set output control.
 * Bit 0=1 : Enable interrupt on "Ready to transfer"