The Signetics 2650 - The MESSUI Place

2708 EPROM programmer
0440 OS OF 08 l3 03 00 08 10 08 013 08 OD 08 08 08 0A
0 45 0 17 3C 00 3D BC 7C 00 3D BC 7D BC 08 7C 09 7111 D9
0 460 02 D8 00 08 74 C9 73 08 6E 09 6D D9 02 DB 00 CS
0 47 0 66 C9 65 ES 5E 16 E9 50 17 3F 00 BA C9 83 CA 8A
0 480 00 84 25 14 3F 02 134 09 FS OE 04 26 DA 6E D9 6C
0 490 18 6A 76 40 77 02 75 18 3F 02 DB CD 04 51 CE 04
04140 52 33 F6 DA 02 D9 00 CD 04 53 CE 04 54 32 EA CD
0 4130 04 55 CE 04 56 07 00 05 05 06 2A 32 96 3F 02 86
0 400 05 05 06 74 38 95 FF 05 1B 05 05 06 50 3B SC 06
0 4D0 3A 3F 04 BC 39 ES 05 05 06 SF 3F 04 79 3F 04 40
04E0 07 06 3F 00 BA 2 0 06 32 00 84 59 EC 84 57 18 19
04F0 09 F7 3F 02 69 0D 04 5A 3B F9 04 20 3F 02 24 FB
0500 04 07 06 32 DE 04 80 C8 II 3F 04 52 1 A 5A 013 OA
0510 IA 06 05 05 06 70 32 C3 92 22 8 0 32 C 1 00 84 57
0 520 CC 84 59 32 ES 1 A 76 IF 04 C6 53 57 49 54 43 48
0 530 20 54 4F 2 0 50 52 4F 47 52 41 4D OD OA 54 46 45
0 540 46 20 50 52 45 53 53 20 41 46 59 20 4B 45 59 00
0 550 53 57 49 54 43 48 20 54 4F 20 52 45 41 44 00 45
0 560 52 52 4F 52 20 40 4F 43 41 54 49 4F 46 53 3A 00
057 0 4E 49 4C 00 50 52 4F 47 52 41 4D 4D 49 46 47 OD
0 53 0 OA 00 FIG. 5
This hex listing is a 2650 version of the
program required to control the
EPROM programming operation.
1000
25VW
is required is to switch to the program
mode, and then to program the
processor to write the appropriate data
to each location in turn, repeating this
writing sequence until the required
number of programming pulses have
been applied to each location.
All of the timing requirements are
provided by the four monostables, all
that the program has to do is provide a
repeated "block move" function. A
block diagram of a simplified routine to
do this is shown in Fig. 2.
Power supply requirements for the
2708 are quite complicated. —5V, +5V
and +12V supplies are required for
normal operation, while +26V is required
during programming. Fig. 3
shows how these voltages can be derived
from a standard transformer, using
zener diode regulators. The +5V supply
can be obtained from the existing circuitry.
86
ELECTRONICS Australia, February, 1979
Shown below is the power supply
circuit. The components marked with
an asterisk (') are already present in the
2650 Minicomputer.
aan VA
(N) = PCB CONNECTION PIN
• IN 2150 MINICOMPUTER
26V
+12V
We have designed a suitable printed
circuit board for mounting the EPROM,
address decoder, monostables and
power supply components. It is coded
79upl, and measures 218 x 81mm.
Provision has been made so that this
board can be used with any suitable
processor. Positive and negative going
hold signals are available, and the write
monostable can be triggered from
either positive or negative going
signals. Any starting address for the
EPROM can be decoded, up to H7C00.
Construction of the board should be
well within the capabilities of most
enthusiasts. We recommend that a
good quality socket, preferably a zeroinsertion
force type, be used for the
2708. The remaining ICs can be
soldered directly in place.
The programming switch can be
mounted directly on the board, using
tinned copper wire, or it can be ex-
PROM PROG
INITIALISE
LOOP COUNTER
SE UP
ADOR SEES
PROGRAM
LOC TION
MGR MENT
AODR SSES
DECREMENT
LOOP COUNTER
SET UP
ADDRESSES
NCR MENT
ADDRESSES
TOP
FIG. 2
This is the flowchart for the controlling
program. Use it to write the routines
required by your processor.
tended with a cable if desired. It should
be placed in a position where accidental
operation is unlikely, to ensure that
no accidental programming occurs.
As the board has to be wired directly
to the address and data busses, we
recommend that it be mounted in the
main computer case. Make sure,
however, that access can be gained
relatively easily to the EPROM socket
and the read/program switch.
NO
PRINT
ADDRESS