Browse Prior Art Database

Storage Accumulator

IP.com Disclosure Number: IPCOM000090065D
Original Publication Date: 1969-Jan-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 2 page(s) / 49K

Publishing Venue

IBM

Related People

Bliss, BE: AUTHOR [+2]

Abstract

Monolithic storage accumulator SAC is used to accumulate values between -0 and +255 by the use of words of seven value bits and one overflow-underflow 0-U bit. SAC has 1024 words of eight bits. Each word is addressed by a ten-bit address held in storage address register SAR.

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Storage Accumulator

Monolithic storage accumulator SAC is used to accumulate values between - 0 and +255 by the use of words of seven value bits and one overflow-underflow 0-U bit. SAC has 1024 words of eight bits. Each word is addressed by a ten-bit address held in storage address register SAR.

The address has an increment field consisting of the three high-order bits that effectively divide SAC into eight areas of 128 words. The seven low-order address bits represent the accumulated value and are used to access a word within a given area.

Initially, SAC is loaded with value bits, as shown, so that the eight areas represent increment values ranging from -4 to +3. SAC is also loaded with the 0- U bits. After the SAC is loaded, it is operated by placing an initial value in SAR. Afterwards, successive increment fields are supplied to SAR, causing the value to be changed until either two overflow bits or two underflow bits are detected. Logic circuit L supplies an overflow or underflow signal to the system terminating operation of SAC. Each time a value is read from SAC, the value bits are fed back to the value field of SAR and represent the accumulated value.

To illustrate the operation, assume that the value field of SAR is initially set to zero. Upon receipt of an increment field, SAC is cycled. For example, assume that it is desired to increment the value by +3. According to the illustrated increment field codes, this requires bits 111. The increment field bits...