PSB7238 SIEMENS [Siemens Semiconductor Group], PSB7238 Datasheet - Page 89

• Manufacturer Part Number: PSB7238
• Description: Joint Audio Decoder-Encoder - Multimode
• Manufacturer: SIEMENS [Siemens Semiconductor Group]

CAEN
DACC
NRW(3-0)
External Memory Interface Register
Value after reset: 00
LDMEM
Semiconductor Group
Load Memory. If LDMEM = 0, the external memory interface is
connected with the program bus. It is used for connecting an external
software RAM or EPROM.
If LDMEM = 1, the external memory interface address and data buses
are connected to the outputs of registers address low/high (at host
address 44/45
respectively. This mode is used to download a program into an external
RAM.
If EA = 1 and LDMEM = 0: Enable address lines (CA bus) to external
SRAM for program/data fetch; no meaning in other cases.
0: CA bus switched off, no program/data fetch possible (reset value).
1: CA bus active, external program/data fetch possible.
Data Access, selects program or data memory connected to
SRAM-interface.
0: program memory connected (reset value).
1: data memory connected, can be written by using “MOV” instruction,
must be read by using “MOVP”.
Number of wait states for external interface. The number of wait states
is NRW (1111
0000
capable of zero wait states.
H
B
after reset. SRAM connected for development purpose should be
B
H
) and data low/high (at host address 46/47
= 0 wait states, 0000
89
Read/Write
B
= 15 wait states), takes the value
Register Description
Data Sheet 1998-07-01
Address 2001
H
),
PSB 7238
H