Browse Prior Art Database

Extended Level Status Block for Computer Systems With Extended Memory Addressing

IP.com Disclosure Number: IPCOM000061644D
Original Publication Date: 1986-Sep-01
Included in the Prior Art Database: 2005-Mar-09
Document File: 2 page(s) / 43K

Publishing Venue

IBM

Related People

Cook, RL: AUTHOR [+5]

Abstract

A technique is described whereby an extended level status block (ELSB) is used in a computer system to increase the address spaces and the size of each address space, thereby increasing the size of the context of a running program. The ELSB uses two segment identifiers to improve programming flexibility and efficiency. The ELSB is located in a high-speed local storage unit which, in effect, constitutes a set of address registers. Normally, an LSB consists of an 11-word block (22 bytes). Addressing capability is extended by making the LSB an 11 double word (44 bytes) block, as shown in the drawing. This 11 double word block is always allocated to a program, loaded and stored when bit 09 of the processor status word is a one. All registers then become 32 bits in length, including the instruction address register.

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 95% of the total text.

Page 1 of 2

Extended Level Status Block for Computer Systems With Extended Memory Addressing

A technique is described whereby an extended level status block (ELSB) is used in a computer system to increase the address spaces and the size of each address space, thereby increasing the size of the context of a running program. The ELSB uses two segment identifiers to improve programming flexibility and efficiency. The ELSB is located in a high-speed local storage unit which, in effect, constitutes a set of address registers. Normally, an LSB consists of an 11-word block (22 bytes). Addressing capability is extended by making the LSB an 11 double word (44 bytes) block, as shown in the drawing. This 11 double word block is always allocated to a program, loaded and stored when bit 09 of the processor status word is a one. All registers then become 32 bits in length, including the instruction address register. If the processor status word bit is 09 and the level status register bit 06 are both zero, the entire system will be in compatibility mode. If the bit is a one, then the system is in extended address mode. The ELSB is unique in that it uses two segment identifiers, a system segment identifier (SSID) and a user segment identifier (USID). The SSID is used for operating system programs and tasks. The USID is used for user application programs and tasks, thereby executing programs mapped by the ELSB. Bit 0 of each register directs which of the two segment identifiers is to be used...