AMD Am79C930 manual ISA Address Size Physical Memory, Description Of Reserved Use

P R E L I M I N A R Y AMD

address needs to be aligned to a 32K boundary in mem- ory space. This alignment requirement should be in- cluded in the Resource Data that is programmed into the Flash device and read by the Plug and Play configura- tion utility. These conditions must be satisfied, since the Am79C930 device's Bus Interface Unit will only use the upper 9 bits of the ISA memory address to determine when an address match has been achieved.

Some of the Am79C930 device's ISA Memory locations have predefined uses and, therefore, are not freely available to the device driver. The following table indi- cates restricted space within ISA Memory map of the Am79C930 device:

Am79C930 Device ISA Plug And Play Mode Memory Restricted Space

ISA Address		Size of	Physical Memory And
in Memory	SIR1[5:3]	Restricted Space	Description Of Reserved Use
MBA+0000h –	000	1 Kbytes	SRAM Memory 0 0000h–0 03FFh
MBA+03FFh			This space is reserved for the interrupt vector
			table of the embedded 80188 core.
MBA+0400h –	000	32 bytes	SRAM Memory 0 0400h–0 041Fh
MBA+041Fh			This SRAM space is inaccessible to the
			80188 embedded core, since the 80188
			core maps the 32 TIR registers of the TAI
			into this portion of 80188 memory space.
MBA+0420h –	000	32 bytes	SRAM Memory 0 0420h–0 042Fh
MBA+043Fh			This SRAM space is inaccessible to the
			80188 embedded core, since the 80188
			core maps the MIR registers of the BIU
			(PIR, PDLC and PUCT) and XCE space into
			this portion of 80188 memory space.
MBA+0440h –	000	64 bytes	SRAM Memory 0 0440h–0 047Fh
MBA+047Fh			This SRAM space is reserved for future use
			and may be decoded for non-SRAM purposes
			in the future.
MBA+7C00h –	111	1K–16 bytes	Flash Memory 1 FC00h–1 FFEFh
MBA+7FEFh			These bytes of the Flash memory also map into
			the ISA Plug and Play Resource Data space.
			Therefore, this space can not be used for
			non-Resource Data purposes.
MBA+7FF0h –	111	16 bytes	Flash Memory 1 FFF0h–1 FFFFh
MBA+7FFFh			These 16 bytes of Flash memory space are
			reserved because they are the location of
			the embedded 80188 core's instruction
			pointer following a Am79C930 device reset
			operation. These 16 bytes must contain the
			first 80188 instructions.
*MBA = ISA Plug and Play Memory Base Address

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