HDSP-2301 HP [Agilent(Hewlett-Packard)], HDSP-2301 Datasheet - Page 20

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

MCM6674 must be replaced by a
faster Bipolar PROM. If this
PROM is programmed with the
code listed in Figure 17, it will de-
code a character font identical to
the MCM6674. This same propaga-
tion delay problem is present with
the MCM6810 RAM. Following
worst case design procedures, the
MCM68A10 1.5 MHz RAM should
be used. To accommodate the ad-
ditional address line made
necessary by the display length
expansion, the two 74LS367
tri-state buffers have been re-
placed with the 74LS244 octal
version. Strobing of the display is
accomplished using the 74197,
74393, and 7490 counter string.
The 74197 is connected as a di-
vide by 8 counter that sequentially
selects the seven rows within the
82S2708. The 74393 is a divide by
256 counter connected so that the
seven lowest outputs select each
of the 128 ASCII characters within
the RAM. The previously unused
input A/output Q
been used as an additional divide
by 2 counter. Thus, when the
highest output of the 74393, 2Q
and the Q
NANDed through 7437, the basic
relationship between load time
and column on time is estab-
lished. However, the external
gating that has been added does
affect the duty factor slightly. Al-
though these additional gates
increase the total package count
by one, they perform the neces-
sary function of ensuring that the
column drivers are turned off be-
fore the clock is gated to the
display. This prevents noise from
being generated on the clock of
the display and eliminates errone-
ous display data. The resultant
duty factor is (23/32) (1/5) or
14.4%. Since the HDSP-2000 is
rated at I
col(max)
A
output of the 7490 are
A
= 410 mA and
of the 7490 has
D
,
Figure 7. 8080A Microprocessor Program Utilizing a 160 Byte RAM Buffer that
Interfaces to the REFRESH CONTROLLER
0004
0005
E500
E000
E002
E003
E005
E0A5
E0A7
E400
E401
E402
E403
E406
E408
E40A
F40C
E40D
E40F
E410
E411
E414
E417
E419
E41B
E41E
E421
E422
E425
E428
E42B
E42E
E430
E433
E436
E437
E43A
E43B
E43C
E43D
E43E
E441
E443
E446
E447
E448
E44B
E44D
E44E
E450
E451
E452
E453
E455
E456
E459
E45A
E45B
E45D
E45E
E45F
E462
E463
E465
E466
E467
E46A
LOC
05
FE
FF
00
A7
00
F5
C5
E5
2A
06
3E
D3
7E
D3
23
05
C2
3A
D3
FE
CA
22
07
32
C3
21
22
3E
32
2A
2B
22
El
Cl
F1
C9
11
0E
2A
7E
23
22
26
6F
06
7E
12
7D
C6
6F
D2
24
7B
C6
5F
05
C2
7B
C6
5F
0D
C2
C9
OBJECT
CODE
E0
FF
E0
00
20
FF
05
04
0C
02
05
EF
28
00
02
3A
05
00
FE
02
03
03
24
20
A5
A5
E5
05
80
5A
20
50
5F
43
E0
E4
E0
E4
E0
E0
E4
E0
E0
E0
E0
E0
E0
E0
E0
E4
E4
E4
SOURCE STATEMENTS
RDVR
CDVR
DECDR
POINT
COLMN
COUNT
BUFFR
ASCII
DATA
RFRSH
LOOP
FIRST
END
LOAD
LOOP1
LOOP2
LOOP3
12
EQU
EQU
EQU
ORG
DW
DB
DW
DS
ORG
DW
DS
ORG
PUSH
PUSH
PUSH
LHLD
MVI
MVI
OUT
MOV
OUT
INX
DCR
JNZ
LDA
OUT
CPI
JZ
SHLD
RLC
STA
JMP
LXI
SHLD
MVI
STA
LHLD
DCX
SHLD
POP
POP
POP
RET
LXI
MVI
LHLD
MOV
INX
SHLD
MVI
MOV
MVI
MOV
STAX
MOV
ADI
MOV
JNC
INR
MOV
ADI
MOV
DCR
JNZ
MOV
ADI
MOV
DCR
JNZ
RET
0004H
0005H
0E500H
0E000H
BUFFR
0FEH
0FFFFH
160
0E0A5H
DATA
32
0E400H
PSW
B
H
POINT
B, 32
A, 0FFH
CDVR
A, M
RDVR
H
B
LOOP
COLMN
CDVR
0EFH
FIRST
POINT
COLMN
END
H, BUFFR
POINT
A, 0FEH
COLMN
COUNT
H
COUNT
H
B
PSW
D, BUFFR+31
C, 32
ASCII
A, M
H
ASCII
H, DECDR/256
L, A
B, 5
A, M
D
A, L
80H
L, A
LOOP3
H
A, E
32
E, A
B
LOOP2
A, E
5FH
E, A
C
LOOP1