Siemens EF 88H Series Manual de usuario descargar pdf (Pagina 83)

Device Specification

Semiconductor Group 7-21

Control of XRAM in the SAB 80C517A

There are two control bits in register SYSCON which control the use and the bus operation

during accesses to the additional On-Chip RAM (XRAM).

Special Function Register SYSCON

Reset value of SYSCON is xxxx xx01B.

The control bit XMAP0 is a global enable/disable bit for the additional On-Chip RAM (XRAM).

If this bit is set, the XRAM is disabled, all MOVX accesses use external memory via the external

bus. In this case the SAB 80C517A does not use the additional On-Chip RAM and is compatible

with the types without XRAM.

Addr. 0B1

——————XMAP1 XMAP0 SYSCON

Bit Function

XMAP0 Global enable/disable bit for XRAM memory.

XMAP0 = 0: The access to XRAM (= On-Chip XDATA memory) is en-

abled.

XMAP0 = 1: The access to XRAM is disabled. All MOVX accesses are per-

formed by the external bus (reset state).

XMAP1 Control bit for RD/WR signals during accesses to XRAM; this bit has no

effect if XRAM is disabled (XMAP0 = 1) or if addresses exceeding the

XRAM address range are used for MOVX accesses.

XMAP1 = 0: The signals RD and WR are not activated during accesses

to XRAM.

XMAP1 = 1: The signals RD and WR are activated during accesses to

XRAM.

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Siemens EF 88H Series Manual de usuario Pagina 83