Description of Selected Instructions

The following information is provided to assist the user in

understanding the operation of several unique instructions

and to provide notes useful to programmers in writing

COP413C programs

XAS INSTRUCTION

XAS (Exchange A with SIO) exchanges the 4-bit contents of

the accumulator with the 4-bit contents of the SIO register

The contents of SIO will contain serial-inserial-out shift reg-

ister or binary counter data depending on the value of the

EN register An XAS instruction will also affect the SK out-

put (See Functional Description EN Register) If SIO is se-

lected as a shift register an XAS instruction must be per-

formed once every four instruction cycle times to effect a

continuous data stream

JID INSTRUCTION

JID (Jump Indirect) is an indirect addressing instruction

transferring program control to a new ROM location pointed

to indirectly by A and M It loads the lower eight bits of the

ROM address register PC with the contents of ROM ad-

this instruction

Note

JID uses two instruction cycles if executed one if skipped

LQID INSTRUCTION

LQID (Load Q Indirect) loads the 8-bit Q register with the

LQID can be used for table look-up or code conversion such

as BCD to 7-segment The LQID instruction ‘‘pushes’’ the

significant eight bits of the PC as follows A

RAM(B)

pointed to by the new address is fetched and loaded into

the Q latches Next the stack is ‘‘popped’’ (SB

PC) restoring the saved value of the PC to continue se-

quential program execution Since LQID pushes SA

x

SB the previous contents of SB are lost

Note

LQID uses two instruction cycles if executed one if skipped

INSTRUCTION SET NOTES

a The first word of a COP413C program (ROM address 0)

must be a CLRA (Clear A) instruction

b Although skipped instructions are not executed one in-

struction cycle time is devoted to skipping each byte of

the skipped instruction Thus all program paths take the

same number of cycle times whether instructions are

skipped or executed (except JID and LQID)

c The ROM is organized into eight pages of 64 words each

The program counter is a 9-bit binary counter and will

count through page boundaries If a JP JSRP JID or

LQID instruction is located in the last word of a page the

instruction operates as if it were in the next page For

example A JP located in the last word of a page will jump

to a location in the next page Also a LQID or JID located

in the last word in page 3 or 7 will access data in the next

group of four pages

COPS Programming Manual

For detailed information on writing COPS programs the

COPS Programming Manual 424410284-001 provides an in-

depth discussion of the COPS architecture instruction set

and general techniques of COPS programming This manual

is written with the programmer in mind

OPTION LISTOSCILLATOR SELECTION

The oscillator option selected must be sent in with the

EPROM of ROM Code for masking into the COP413C Se-

lect the appropriate option make a photocopy of the table

and send it with the EPROM

COP413CCOP313C

Option 1 Oscillator selection

e

0 Ceramic Resonator input frequency divided by 8

CKO is oscillator output

e

1 Single pin RC controlled oscillator divided by 4 CKO

is no connection

Note

The following option information is to be sent to Na-

tional along with the EPROM

is Oscillator Selected

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