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IA2910A

Microprogram Controller

Copyright

© 1999, InnovASIC Inc.

Customer Specific IC Solutions

Instruction Set Description

Table 2

I(3:0)

Mnemonic

Name

Reg/cntr

contents

Fail

Y

Fail

Stack

Pass

Y

Pass

Stack

Reg/cntr

Enable

0

JZ

Jump Zero

X

0

CLEAR

0

CLEAR

HOLD

PL

1

CJS

Cond JSB PL

X

PC

HOLD

D

PUSH

HOLD

PL

2

JMAP

Jump Map

X

D

HOLD

D

HOLD

HOLD

MAP

3

CJP

Cond Jump PL

X

PC

HOLD

D

HOLD

HOLD

PL

4

PUSH

Push/cond LD

cntr

X

PC

PUSH

PC

PUSH

NOTE 1

PL

5

JSRP

Cond JSB R/PL

X

R

PUSH

D

PUSH

HOLD

PL

6

CJV

Cond Jump

Vector

X

PC

HOLD

D

HOLD

HOLD

VECT

7

JRP

Cond Jump

R/PL

X

R

HOLD

D

HOLD

HOLD

PL

8

RFCT

Repeat Loop,

Cntr .NE. 0

.NE. 0

= 0

F

PC

HOLD

POP

F

PC

HOLD

POP

DEC

HOLD

PL

PL

9

RPCT

Repeat PL, cntr

.NE. 0

.NE. 0

= 0

D

PC

HOLD

HOLD

D

PC

HOLD

HOLD

DEC

HOLD

PL

PL

10

CRTN

Cond RTN

X

PC

HOLD

F

POP

HOLD

PL

11

CJPP

Cond Jump PL

& POP

X

PC

HOLD

D

POP

HOLD

PL

12

LDCT

LD Cntr &

Continue

X

PC

HOLD

PC

HOLD

LOAD

PL

13

LOOP

Test End Loop

X

F

HOLD

PC

POP

HOLD

PL

14

CONT

Continue

X

PC

HOLD

PC

HOLD

HOLD

PL

15

TWB

Three-Way

Branch

.NE. 0

= 0

F

D

HOLD

POP

PC

PC

POP

POP

DEC

HOLD

PL

PL

NOTE 1: If CCENn is LOW and CCn is HIGH, HOLD; ELSE LOAD.

X = Don’tCare

.NE. = Not equal

IA2910A Instruction Set

The IA2910A provides sixteen instructions which select the address of the next microinstruction to

be executed. Four of the instructions are unconditional –their effect depends only on the

instruction. Ten of the instructions have an effect which is partially controlled by an external, data-

dependent condition. Three of the instructions have an effect which is partially controlled by the

contents of the internal register/counter. The instruction set is shown in Table 2. Examples of the

Instruction Execution are illustrated in Figure 2. In this discussion it is assumed that CIN is tied

HIGH.

In the ten conditional instructions, the result of the data-dependent test is applied to CCn. If the

CCn input is LOW, the test is considered to have been passed, and the action specified in the name

occurs; otherwise, the test has failed and an alternate (often simply the execution of the next

sequential microinstruction) occurs. Testing of CCn may be disabled for a specific microinstruction

by setting CCENn HIGH, which unconditionally forces the action specified in the name; that is, it

forces a pass. Other ways of using CCENn include (1) tying it HIGH, which is useful if no

microinstruction is data-dependent; (2) tying it LOW if data-dependent instructions are never