IBM nec pd78082 User Manual

The memory to be manipulated in the fixed space is directly addressed with 8-bit data in an instruction word.

The fixed space to which this address is applied is a 256-byte space of addresses FE20H through FF1FH.  An

internal high-speed RAM and a special-function register (SFR) are mapped at FE20H to FEFFH and FF00H to

FF1FH, respectively.

The SFR area (FF00H through FF1FH) to which short direct addressing is applied is a part of the entire SFR

area.  To this area, ports frequently accessed by the program, and the compare registers and capture registers

of timer/event counters are mapped.  These SFRs can be manipulated with a short byte length and a few clocks.

When 8-bit immediate data is at 20H to FFH, bit 8 of an effective address is set to 0.  When it is at 00H to 1FH,

bit 8 is set to 1.  Refer to [Illustration] on next page.

Identifier

Description

saddr

Label of FE20H to FF1FH immediate data

saddrp

Label of FE20H to FF1FH immediate data (even address only)