Memory Configuration and Bank Switching
Index R/W Mode Description
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-80h R/W bit 7 unused
bits 6-4 = 111b 3-bit NRCE 1st half wait state value (default)
bit 3 unused
bits 2-0 = 111b 3-bit NRCE 2nd half wait state value (default)
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-81h R/W bit 7 = 0b 512 cycles/8mS DRAM refresh rate (default)
bits 6-2 unused
bits 1-0 = 11b 2-bit NRAS[3:0] wait state value (default)
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-82h R/W bits 7-4 = 1111b 4-bit NCS[1] wait state value (default)
bits 3-0 = 1111b 4-bit NCS[0] wait state value (default)
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-83h R/W bits 7-4 unused
bits 3-0 = 1111b 4-bit ISA wait state value (default)
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-84h R/W bits 7-3 unused
bits 2-0 = 001b size of NRAS[0] RAM mapped into CPU address space
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-85h R/W bits 7-3 unused
bits 2-0 = 001b size of NRAS[1:0] RAM mapped into CPU address space
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-86h R/W bit 7 unused
bit 6 = 0 NCS[1] write disabled (default)
bit 5 = 0 NCS[0] write disabled (default)
bit 4 = 1 NRAS[3] write enabled (default)
bit 3 = 1 NRAS[2] write enabled (default)
bit 2 = 1 NRAS[1] write enabled (default)
bit 1 = 1 NRAS[0] write enabled (default)
bit 0 = 0 NRCE write disabled (default)
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-87h R/W bits 7-0 = A0h Write protect register (CPU address bits [19:12])
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-88h R/W bits 7-0 Bank D0 frame select (device address bits [25:18])
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-89h R/W bits 7-4 Bank D0 frame select (device address bits [17:14])
bit 3 = 0 Bank D0 not enabled (default)
bits 2-0 = 000 NRCE Bank D0 device select code
= 001 NRAS[0]
= 010 NRAS[1]
= 011 NRAS[2]
= 100 NRAS[3]
= 101 NCS[0]
= 110 NCS[1]
= 111 unused
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-8Ah R/W bits 7-0 Bank D1 frame select (device address bits [25:18])
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-8Bh R/W bits 7-4 Bank D1 frame select (device address bits [17:14])
bit 3 = 0 Bank D1 not enabled (default)
bits 2-0 Bank D1 device select code (see -89h)
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-8Ch R/W bits 7-0 Bank D2 frame select (device address bits [25:18])
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-8Dh R/W bits 7-4 Bank D2 frame select (device address bits [17:14])
bit 3 = 0 Bank D2 not enabled (default)
bits 2-0 Bank D2 device select code (see -89h)
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-8Eh R/W bits 7-0 Bank D3 frame select (device address bits [25:18])
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-8Fh bits 7-4 Bank D3 frame select (device address bits [17:14])
bit 3 = 0 Bank D3 not enabled (default)
bits 2-0 Bank D3 device select code (see -89h)
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-90h R/W bits 7-0 Bank E0 frame select (device address bits [25:18])
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-91h R/W bits 7-4 Bank E0 frame select (device address bits [17:14])
bit 3 = 0 Bank E0 not enabled (default)
bits 2-0 Bank E0 device select code (see -89h)
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-92h R/W bits 7-0 Bank E1 frame select (device address bits [25:18])
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-93h R/W bits 7-4 Bank E1 frame select (device address bits [17:14])
bit 3 = 0 Bank E1 not enabled (default)
bits 2-0 Bank E1 device select code (see -89h)
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-94h R/W bits 7-0 Bank E2 frame select (device address bits [25:18])
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-95h R/W bits 7-4 Bank E2 frame select (device address bits [17:14])
bit 3 = 0 Bank E2 not enabled (default)
bits 2-0 Bank E2 device select code (see -89h)
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-96h R/W bits 7-0 Bank E3 frame select (device address bits [25:18])
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-97h R/W bits 7-4 Bank E3 frame select (device address bits [17:14])
bit 3 = 0 Bank E3 not enabled (default)
bits 2-0 Bank E3 Device Select code (see -89h)
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-98h R/W bits 7-0 Bank C Frame Select (device address bits [25:18])
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-99h R/W bits 7-6 Bank C Frame Select (device address bits [17:16])
bit 5 unused
bit 4 = 0 Bank C Attribute Memory Select
bit 3 = 0 Bank C not enabled (default)
bits 2-0 Bank C Device Select code (see -89h)
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-9Ah R/W bits 7-0 Disp Memory Frame Select (device address bits [25:18])
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-9Bh R/W bits 7-4 Disp Memory Frame Select (device address bits [17:14])
bit 3 unused
bits 2-0 Disp Memory Device Select code (NRAS[3:0] only)
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-9Ch R/W bits 7-0 Font Table Frame Select (device address bits [25:18])
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-9Dh R/W bits 7-4 Font Table Frame Select (device address bits [17:14])
bit 3 unused
bits 2-0 Font Table Device Select code (see -89h)
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-9Eh R/W bit 7 = 0 Bank E3 Attribute Memory Select
bit 6 = 0 Bank E2 Attribute Memory Select
bit 5 = 0 Bank E1 Attribute Memory Select
bit 4 = 0 Bank E0 Attribute Memory Select
bit 3 = 0 Bank D3 Attribute Memory Select
bit 2 = 0 Bank D2 Attribute Memory Select
bit 1 = 0 Bank D1 Attribute Memory Select
bit 0 = 0 Bank D0 Attribute Memory Select
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-9Fh R/W bits 7-0 unused
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-A0h R/W bits 7-0 I/O Window 0 start address upper byte (I/O address bits
[15:8])
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-A1h R/W bits 7-0 I/O Window 0 start address lower byte (I/O address bits
[7:0])
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-A2h R/W bits 7-0 I/O Window 0 size register (must be power of 2)
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-A3h R/W bits 7-5 unused
bit 4 = 0 Overlapping I/O-Address Window 0 not enabled (default)
bit 3 = 0 I/O Window 0 not enabled (default)
bits 2-0 = 101 NCS[0] I/O Window 0 Device Select code
= 110 NCS[1]
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-A4h R/W bits 7-0 I/O Window 1 start address upper byte (I/O address bits
[15:8])
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-A5h R/W bits 7-0 I/O Window 1 start address lower byte (I/O address bits
[7:0])
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-A6h R/W bits 7-0 I/O Window 1 size register (must be power of 2)
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-A7h R/W bits 7-5 unused
bit 4 = 0 Overlapping I/O-Address Window 1 not enabled (default)
bit 3 = 0 I/O Window 1 not enabled (default)
bits 2-0 = 101 NCS[0] I/O Window 1 Device Select code
= 110 NCS[1]
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