NEC uPD78P078 - Manual (Page 559)

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CHAPTER 26 ROM CORRECTION
26.1 ROM Correction Functions
The
µ
PD78078, 78078Y Subseries can replace part of a program in the mask ROM with a program in the internal
expansion RAM.
Instruction bugs found in the mask ROM can be avoided, and program flow can be changed by using the ROM
correction.
The ROM correction can correct two places (max.) of the internal ROM (program).
Caution The ROM correction cannot be emulated by the in-circuit emulator (IE-78000-R, IE-78000-R-A
IE-78001-R-A, IE-78K0-NS).
26.2 ROM Correction Configuration
The ROM correction is executed by the following hardware.
Table 26-1. ROM Correction Configuration
Item Configuration
Register Correction address registers 0 and 1 (CORAD0, CORAD1)
Control register Correction control register (CORCN)
Figure 26-1 shows a block diagram of the ROM correction.
Figure 26-1. Block Diagram of ROM Correction
Remark n = 0, 1
Match
CORENn CORSTn
Program counter (PC)
Comparator
Correction address
register (CORADn)
Internal bus
Correction control register
Correction branch request
signal (BR !7FDH)