Specifications

EPC-5A Hardware & Software Reference Manual

Page 80

Bits 3-0 Use the address modifier (in binary form) to determine the

appropriate values for these bits. 2Dh = 0010110

Bit 3 (Address Modifier bit 5) = 1

Bit 2 (Address Modifier bit 4) = 0

Bit 1 (Address Modifier bit 2) = 1

Bit 0 (Address Modifier bit 1) = 0

Thus, 8151h should be set to 1100 1010 or CAh.

5. Map the address.

Add the A16 address to the memory window address

Addr

←

E0000000h + A16 address

6. Read the data.

Data

←

value pointed to by Addr

Microsoft C code for Example 1 -

#define WORD unsigned short

#define LWORD unsigned long

WORD addr; /* 16-bit A16 address */

WORD data;

WORD far * wptr;

outp(0x8104,(inp(0x8104)|2)); /* set VME access bit */

outp(0x8130,0xFC);

outp(0x8150,0xFF);

outp(0x8151,0xCA); /* Set address modifier to A16 supervisory access */

wptr = (WORD far *) (0xE0000000L + addr);

data = *wptr; /* Read through window */