The USSC90, the codecard.


                                         Left of the keypad: the code-card.


For programmers a code card was provided,
a reference card containing all important numbers.





The first side 

displays three tables of addresses in the memory,
to or from these patterns the data was 
read or written from/to the buffers.  
These buffers interfaced with the printer, 
the card-reader and the read-punch unit.



The second side displays a table with the codes for the 39 instructions. This table cdisplays six columns; - The numeric-code of the instruction, - the meaning of M, the operand-address, - the meaning of C, the address of the next instruction, - the description of the the action, - the time needed for these instructions and - pointers to the notes.

The third side displays - the notes, - the abbreviations and - the special bit-patterns to address the registers.

The fourth side displays two tables with the bit-patterns of the machine-code and of the RR-code, referring to the results of the two translating-instructions. And one table with the values of odd bit-combinations. These codes were specific for the USSC90, the USSC80 used differend A/N-codes.
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