PEP Modular Computers 15311, User Manual

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VMEM-F1 Chapter 2 Functional Description
July 30, 1997 Page 2- 5 © PEP Modular Computers
2.3 Addressing Memory
The VMEM-F1 occupies 4 MByte of the VMEbus A24/D16 address space. The base address is pro-
grammable in 4 MByte blocks via the board base address register (see ...)
In order to reach the whole of the 192 MByte, the area is paged in blocks of 4 MByte.
On the VMEM-F1, one page represents one FLASH bank, which is physically built up of a pair of
FLASH chips. Within one page, the whole memory can be linearly addressed. The FLASH page is se-
lected via the FLASH page register (see...).
Before addressing memory, the following configuration registers must be initialized:
• Memory base address register , which defines the FLASH memory address.
• Memory address mask register , which defines the FLASH page size.
• Memory address modifier code register , which defines the board address modifier codes.
• Memory page register , which defines the currently used FLASH page.
2.3.1 Memory Base Address Register
Address: Jumper selected A16 base a HEX 7
Format: Byte
Access: Read and write
Value after Reset: HEX 00
Register Description:
A23 A22
Memory Base
Address (HEX)
0 0 00 00 00
0 1 40 00 00
1 0 80 00 00
1 1 C0 00 00
Reserved
Reserved
Reserved
Reserved
0 1 2 3 4 5 6 7
A23
Reserved
Reserved A22