公开(公告)号：BR9405259A

公开(公告)日：1995-10-03

申请号：BR9405259

申请日：1994-12-27

Applicant: IBM

Inventor： PADGETT RUSSEL S ,  AMADO NASSIFF ,  RAUENZAHN SPENCER G II

IPC: G06F13/14 ,  G06F9/445 ,  G06F12/06 ,  G06F13/40 ,  G06F15/177

Abstract: Method and apparatus for enabling configuration of a PCI daughter card residing on an MCA adapter card using MCA setup cycles and signals and for ensuring the allocation of memory space to the daughter card. In a preferred embodiment, the invention comprises an MCA adapter card connected to an MCA system bus of a conventional PC. A PCI-compliant daughter card, the purpose of which is to provide additional functionality to circuitry of the adapter card, resides on a PCI bus of the adapter card. A PCI/MCA bridge is provided for interfacing the MCA system bus with the PCI bus of the adapter card for enabling configuration of the daughter card during the setup sequence of the MCA bus and to respond with an appropriate ROM signature during DOS boot-up to ensure that memory space will be allocated to the daughter card, if needed. A first set of XPOS registers of the adapter card are used selectively to enable the bridge and to allow the PCI configuration space, or registers, of the daughter card and other PCI-compliant devices on the daughter card to be selectively accessed and initialized. Certain registers of a second set of XPOS registers are used to set the data flow mode of the bridge and to respond with the correct ROM signature at DOS boot-up of the PC. The remaining ones of the second set of XPOS registers are used selectively to enable and to store the size and location of any necessary RAM and/or ROM apertures of the daughter card, thereby enabling the bridge to initiate a PCI operation to the daughter card if it decodes an address within either of the apertures.

公开(公告)号：BR9005633A

公开(公告)日：1991-09-17

申请号：BR9005633

申请日：1990-11-07

Applicant: IBM

Inventor： PADGETT RUSSEL S ,  CHISHOLM DOUGLAS R ,  GARCIA SERAFIN JOSE E JR ,  ALVAREZ RAFAEL ,  KALMAN DEAL A ,  YODER ROBERT D

IPC: G06F12/06 ,  G06F12/02 ,  G06F13/16 ,  G06F13/14

Abstract: A selected address within one of two segments of a memory space (124) of a second address/data bus (116), can be accessed from a first bus (102) through one of two data registers (136 and 138). In addition, the location of the two segments within the memory space of the second bus is selectable through two segment registers (148 and 150), which are accessed from the first bus through the first data register (136). A two byte wide "mode" register (126 and 128), which can be directly accessed from the first bus, stores data within three ranges. When the mode register data is within the first range, a selected segment register can be accessed through the first data register. A first value within this range selects the first segment register (148), while a second value selects the second segment register (150). Data loaded into the first and second segment registers points to first and second segments of the second memory space, respectively. When the mode register data is within the second range, this data functions as a pointer to select an address within a selected segment. The selected address is accessed through the data registers; the first data register (136) accessing the selected address in the first segment, while the second data register (138) accesses the selected address in the second segment. After a selected address has been accessed, an auto-increment circuit increments the mode register so that the next sequential address in the selected segment can be accessed without having to reload the mode register. When the mode register data is within the third range, the two data registers can be directly accessed from the first bus.