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IBM 5080 Base Addressing Capability

IP.com Disclosure Number: IPCOM000122139D
Original Publication Date: 1991-Nov-01
Included in the Prior Art Database: 2005-Apr-04
Document File: 3 page(s) / 74K

Publishing Venue

IBM

Related People

Fiore, AM: AUTHOR [+3]

Abstract

A base address register is provided to support the following graphics orders: BASE ADDRESSING ORDER SET: GADD GSUB GCOMP GTM GMVA GMVW

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This is the abbreviated version, containing approximately 52% of the total text.

IBM 5080 Base Addressing Capability

      A base address register is provided to support the
following graphics orders: BASE ADDRESSING ORDER SET:
      GADD
      GSUB
      GCOMP
      GTM
      GMVA
      GMVW

      When activated, the base addressing register provides the page
number to be applied with the offset provided in the address word of
the above orders.

      Base addressing is only applicable with the absolute addressing
mode (SM '28' and '2A').  The relative addressing modes (SM '2C' and
'28') remain applicable to the current page.  The base addressing
mode is controlled by a new order:
      GSBAR - Set Base Address Register Mode
                2AEO
           0010      1010      xxxx      xxxx  =   SM/MC
           MU00      0000      BBBB      BBBB  =   Immediate Data
List
                28EO
           0010      1000      xxxx      xxxx  =   SM/MC
           AAAA      AAAA      AAAA      AAA     =   Indirect Data
Point er
           MU00      0000      BBBB      BBBB  =   Indirect Data List
M MODE BIT:
     0 = Normal 5085 Addressing Mode.  The base register is not
applied to the base addressing order set.
     1 = Base Addressing Mode.  Use the contents of the base address
register when creating the complete address (page + offset) for
operand 1 for the orders in the base addressing order set.

      Persistence:  Once the base addressing mode is entered, it
applies to all orders in the base addressing order set until:
      -    mode is reset to normal 5085 addressing mode
      -    GBGOP (for 3250 GSRT)
      -    Start Display Program SF (or 3250 SBA and Start CC)

      The contents of the base address register may be set with this
same instruction or may have been previously established (by this
same instruction) at an earlier point in time and will apply from
this point.
U...