HDSP-2301 HP [Agilent(Hewlett-Packard)], HDSP-2301 Datasheet - Page 18

• Manufacturer Part Number: HDSP-2301
• Description: Four Character 5.0 mm (0.20 inch) 5 x 7 Alphanumeric Displays
• Manufacturer: HP [Agilent(Hewlett-Packard)]

74393, waveform
logical 1. The circuit then scans 32
characters from the RAM and seri-
alizes the column data by
counting through each of the
seven rows of the 6674 and gating
the appropriate column of the
display. During the seven counts
when 2Q
74393 are not equal to a logical 1,
the column data is displayed, as
shown in waveform
factor of the display shown in
Figure 13 is 17.5%.
Changing the display length to 64
characters is a simple modifica-
tion. This configuration can be
easily realized by disconnecting
2Q
and connecting it through the re-
maining tri-state buffer on the
74LS367 and using the 6810 RAM
to store 64 ASCII characters.
By leaving only 2Q
attached to the 7410, the column
on time of the display is reduced
from 17.5% to 15%. This reduction
is caused because the relationship
between actual column on time
and theoretical column on time is
3/4 as opposed to 7/8 for the 32
characters. Since the display
length has been doubled, the drive
transistors must be upgraded to
handle the higher column currents.
To implement a 128 character dis-
play, several modifications are
needed. These changes are incor-
porated into the circuit in Figure
16. First, the input clock fre-
quency has been increased to 2
MHz. This has been done to main-
tain a refresh rate of
approximately 100 Hz for each
digit, thus providing a flicker-free
display. This higher speed of op-
eration causes propagation delay
problems within the MCM6674
(NMOS) whose maximum access
time is 350 ns. For this reason, the
B
of the 74393 from the 7410
B
, 2Q
C
, and 2Q
C
goes to a
and 2Q
). The duty
D
of the
D
Figure 6. 6800 Microprocessor Program Utilizing a 160 Byte RAM Buffer that
Interfaces to the REFRESH CONTROLLER
0000
0002
0003
0005
0007
0009
000B
000C
000D
00AD
0400
0400
0402
0405
0407
0409
040C
040E
04A2
04A4
04A7
04A9
04AC
04AE
04B0
04B2
04B4
04B6
04B8
04BB
04BC
04BF
04C0
04C3
04C5
04C7
04C8
04CA
04CC
04CE
04CF
04D0
04D3
04D5
04D7
04D9
04DB
04DD
04DF
04E1
04E3
04E5
04E8
04EA
04EC
04ED
04EF
04F1
04F2
04F4
04F6
04F8
04FA
04FC
04FD
04FF
0502
0504
0506
0508
050B
050E
0510
LOC
BF
Bl
06
00
86
B7
DE
A6
B7
A6
B7
A6
B7
96
B7
81
27
D6
CB
D7
24
7C
OD
79
3B
CE
DF
DE
09
DF
86
97
3B
5F
CE
DF
86
97
86
97
86
97
9B
24
7C
97
DE
09
A6
DF
1B
97
DE
A6
DE
A7
08
DF
7A
26
CB
24
7C
7A
26
39
OBJECT
CODE
05
04
00
AD
FF
BF
00
00
BF
01
BF
1F
BF
02
BF
EF
10
00
20
00
03
00
00
00
00
03
03
FE
02
00
07
06
09
05
OB
20
0C
06
03
00
06
05
00
05
0A
09
00
07
00
07
00
E6
80
03
00
00
CD
05
04
04
04
05
00
02
OD
OD
05
0C
09
0B
SOURCE STATEMENTS
*
*
CDVR
RDVR
DECDR
POINT
COLMN
COUNT
ASCII
DISPNT
DCRPNT
COLCNT
DIGCNT
BUFFR
DATA
RFRSH
LOOPHH
LOOPA
LOOPB
LOAD
LOOP I
LOOP2
LOOP3
LOOP4
10
EQU
EQU
EQU
RMB
RMB
RMB
FDB
RMB
RMB
RMB
RMB
RMB
RMB
ORG
LDA A
STA A
LDX
LDA A
STA A
LDA A
STA A
LDA A
STA A
LDA A
STA A
CMP A
BEQ
LDA B
ADD B
STA B
BCC
INC
SEC
ROL
RTI
LDX
STX
LDX
DEX
STX
LDA A
STA A
RTI
CLR B
LDX
STX
LDA A
STA A
LDA A
STA A
LDA A
STA A
ADD A
BCC
INC
STA A
LDX
DEX
LDA A
STX
ABA
STA A
LDX
LDA A
LDX
STA A
INX
STX
DEC
BNE
ADD B
BCC
INC
DEC
BNE
RTS
•
•
•
$BF05
$BF04
$0600
2
1
2
DATA
2
2
1
1
160
32
$0400
I, $FF
E, CDVR
D, POINT
X, 0
E, RDVR
X, I
E, RDVR
X, 31
E, RDVR
D, COLMN
E, CDVR
I, $EF
LOOPB
D, POINT +1
I, 32
D, POINT +1
LOOPA
E, POINT
E, COLMN
I, BUFFER
D, POINT
D, COUNT
D, COUNT
I, $FE
D, COLMN
I, BUFFR
D, DISPNT
I, <DECDR
D, DCRPNT
I, 5
D, COLCNT
I, 32
D, DIGCNT
D, ASCII+1
LOOP2
E, ASCII
D, ASCII+1
D, ASCII
X, 0
D, ASCII
D, DCRPNT+1
D, DCRPNT
X, 0
D, DISPNT
X, 0
D, DISPNT
E, DIGCNT
LOOP3
I, $80
LOOP4
E, DCRPNT
E, COLCNT
LOOP1