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9) divisor latch (ls, ms), 8 parallel port, Parallel port -7 – Acrosser AR-B1320 User Manual

Page 15

background image

A

A

R

R

-

-

B

B

1

1

3

3

2

2

0

0

U

U

s

s

e

e

r

r

s

s

G

G

u

u

i

i

d

d

e

e

(9)

Divisor Latch (LS, MS)

Byte Data

LS

MS

Bit 0:

Bit 0

Bit 8

Bit 1:

Bit 1

Bit 9

Bit 2:

Bit 2

Bit 10

Bit 3:

Bit 3

Bit 11

Bit 4:

Bit 4

Bit 12

Bit 5:

Bit 5

Bit 13

Bit 6:

Bit 6

Bit 14

Bit 7:

Bit 7

Bit 15

Desired

Baud Rate

Divisor Used to

Generate 16x Clock

Present Error Difference

Between Desired and Actual

50 2304

---

75 1536

---

110 1047

0.026

134.5 857

0.058

150 768

---

300 384

---

600 192

---

1200 96

---

1800 64

---

2000 58

0.69

2400 48

---

3600 32

---

4800 24

---

7200 16

---

9600 12

---

14400 8

---

19200 6

---

28800 4

---

38400 3

---

57600 2

---

115200 1

---

Table 2-4 Serial Port Divisor Latch

2.8 PARALLEL

PORT

(1) Register Address

Port Address

Read/Write

Register

base+0 Write

Output

data

base+0 Read

Input

data

base+1

Read

Printer status buffer

base+2

Write

Printer control latch

(2) Printer Interface Logic

The parallel portion of the SMC37C669 makes the attachment of various devices that accept
eight bits of parallel data at standard TTL level.

2-7