Intel 8XC196NT, User Manual

Page: 100 / 597

4-33
MEMORY PARTITIONS
The 32K×16 RAM stores far data at addresses 10000–1FFFFH; code could also execute from this
RAM. The 64K×16 flash memory stores code and additional far data at addresses 20000–
3FFFFH. Because addresses 20000–3FFFFH reside in a single memory component, only one
EPORT line (EPORT.1, which provides address line A17) is necessary. EPORT.1 at a logic zero
selects the 32K×16 RAM, while EPORT.1 at a logic one selects the 64K×16 flash. Any of the four
bus-timing modes can be selected because two address latches are used. (See “Bus Timing
Modes” on page 14-34.) Table 4-14 lists the memory addresses for this example.
Figure 4-11. A 1-Mbyte System with a 16-bit Bus
A3057-03
EA#
BUSWIDTH
EPORT.1
AD15:8
D15:8
A14:7
A6:0
D7:0
OE# UB#
AD7:0
ALE
RD# WRH#
D7:0
D15:8
OE# WE#
74LS373
87C196NT
WRL#
LB#
V
CC
A6:0
A15:7
74LS373
CE#
Page 01H
32K × 16 RAM
(code or far data)
10000–1FFFFH
CE#
Pages 02H and 03H
64K × 16 Flash
(code or far data)
20000–3FFFFH
A17
Page 00H
000000–0005FFH,
001F00–009FFFH
Page FFH
FF0400–FF05FFH,
FF2000–FF9FFFH
A7:1
A7:1