Chapter 26 Rom Correction; Rom Correction Functions; Rom Correction Configuration; Block Diagram Of Rom Correction - NEC PD78076 User Manual

26.1 ROM Correction Functions

The 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.
Item
Register
Control register
Figure 26-1 shows a block diagram of the ROM correction.
Program counter (PC)
Comparator
Correction address
register (CORADn)
Remark n = 0, 1

CHAPTER 26 ROM CORRECTION

Table 26-1. ROM Correction Configuration
Correction address registers 0 and 1 (CORAD0, CORAD1)
Correction control register (CORCN)
Figure 26-1. Block Diagram of ROM Correction
Match
CORENn CORSTn
Internal bus
Configuration
Correction branch request
signal (BR !7FDH)
Correction control register
559