Memory in the CDC 1604 consisted of 32K 48-bit words of magnetic core memory with a cycle time of 6.4 microseconds.
It was organized as two banks of 16K words each, with odd addresses in one bank and even addresses in the other.
The two banks were phased 3.2 microseconds apart, so average effective memory access time was 4.8 microseconds.
 The computer executed about 100,000 operations per second.

Each 48-bit word contained two 24-bit instructions.
The instruction format was 6-3-15: six bits for the operation code, three bits for a "designator" (index register for memory access instructions, condition for jump (branch) instructions) and fifteen bits for a memory address (or shift count, for shift instructions).

The CPU contained a 48-bit accumulator (A), a 48-bit mask register (Q), a 15-bit program counter (P), and six 15-bit index registers (1-6).
Internal integer representation used ones' complement arithmetic.
 Internal floating point format was 1-11-36: one bit of sign, eleven bits of offset (biased) binary exponent, and thirty-six bits of binary significand.

The most-significant three bits of the accumulator were converted from digital to analog and connected to a tube audio amplifier contained in the console.
 This facility could be used to program audio alerts for the computer operator, or to generate music.
 Those familiar with the inner workings of the software could often hear what parts of a task were being performed by the CDC 1604; as a debugging aid, for example, a never-ending repetitive musical phrase indicated the program was stuck in a loop.
Memory in the CDC 1604 consisted of 32K 48-bit words of magnetic core memory with a cycle time of 6.4 microseconds. It was organized as two banks of 16K words each, with odd addresses in one bank and even addresses in the other. The two banks were phased 3.2 microseconds apart, so average effective memory access time was 4.8 microseconds.  The computer executed about 100,000 operations per second.
Each 48-bit word contained two 24-bit instructions. The instruction format was 6-3-15: six bits for the operation code, three bits for a "designator" (index register for memory access instructions, condition for jump (branch) instructions) and fifteen bits for a memory address (or shift count, for shift instructions).
The CPU contained a 48-bit accumulator (A), a 48-bit mask register (Q), a 15-bit program counter (P), and six 15-bit index registers (1-6). Internal integer representation used ones' complement arithmetic.  Internal floating point format was 1-11-36: one bit of sign, eleven bits of offset (biased) binary exponent, and thirty-six bits of binary significand.
The most-significant three bits of the accumulator were converted from digital to analog and connected to a tube audio amplifier contained in the console.  This facility could be used to program audio alerts for the computer operator, or to generate music.  Those familiar with the inner workings of the software could often hear what parts of a task were being performed by the CDC 1604; as a debugging aid, for example, a never-ending repetitive musical phrase indicated the program was stuck in a loop.
CDC 1604