RCA RMB-167 manual Moving RMON167 to Eprom, Eprom CFG1

		Address Range
Jumpers	0-7FFFh		8000h-FFFFh
inserted
none	RAM		RAM
CFG0	EPROM		RAM
CFG1	RAM		EPROM
CFG0 and	EPROM		EPROM
CFG1

The EPROM at low memory may contain start-up code which is executed upon reset. In this case the jumper at P0.4 must be removed so that the microcontroller does not enter the bootstrap loader mode. The microcontroller simply starts executing from address 0.

With the jumpers CFG0 or CFG1 (or both) installed, the RMB-167 may still be bootstrapped. Again, the jumper P0.4 must be installed. This forces the SAB-C167 to enter the bootstrap mode upon reset. The bootstrap sequence terminates with a software reset instruction which starts executing the program starting at address 0. With CFG0 installed, this is the beginning of EPROM. That is, upon bootstrap, the code in EPROM is executed. While possible, first bootstrapping and then executing the code in EPROM is somewhat superfluous since any initialization code of the bootstrap loader may be placed in EPROM.

5.4Moving RMON167 to EPROM

As an example of placing a valid program in EPROM, consider modifying the monitor program RMON167 as given below. It is assumed that the lower 32K of memory is EPROM, and the higher 32K is RAM. The origin of the program is changed to 1000h. Note that the monitor needs buffers to store the commands and the parameters. These buffers are defined to occupy the beginning of RAM at 8000h. Also, the greeting message is changed to indicate that it is the EPROM version of the monitor.

Only the beginning few instructions and the greeting message are changed. Namely,

1.The buffers are moved to 8000h and 8020h, respectively,

2.Jump statements are placed at RESET and NMI vectors,

3.The origin of the monitor program is moved to 1000h

4.The initialization to CPS is now accomplished by an inter-segment jump to 1010h,

5.And finally, the greeting message is changed.

Also note that the address of register SYSCON is different in the SAB80C166 and SAB C167 microcontrollers. The monitor program must be assembled by specifying the C167 register definitions. The program listing follows.

CODE0 section code AT 0000h

;r15 is used for flags:

;bit 0 - error

;1 - dash

;2 - equal

;3 -

;---------------------------------------------------

;--- monitor system variables ---

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