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COMPORT.LZH
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COMPORT.JR
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Text File
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1990-10-06
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9KB
|
201 lines
This message was real grunged when it arrived here. I have reconstructed
it. This uses an internal modem card to make a regular com port. It
doesn't solve the 9600 baud problem. My fix, if it tests out would still
be necessary.
David Lescohier
+------------------------------------------+
|Internal Modem Conversion to Serial Port 1|
+------------------------------------------+
by Roland Fritz
This daughter card is constructed to plug into the PCjr Internal
Modem, converting it to a serial port. Two serial peripherals can then
be used without switching and correct port addresses are still provided
by the internal modem. The mod is reversible, is half the cost, and
takes 1/4 the labor of building a replacement board. Available baud
rates are the same as the other PCjr serial port. Solder skills and use
of a Voltmeter are required. A small notch will be cut out of the rear
of the PCjr cover for this cable. The PCjr internal modem diagnostic
does not expect to see this mod and would report an error. Test it with
an external modem or mouse assigned to port 1.
+---------+
|SCHEMATIC|
+---------+
+------------------------------------------------------------+
|8250A pins not passed thru to the original modem socket are:|
| 10 11 31-34 36-39 |
+------------------------------------------------------------+
+5v
| +---+
| | | signal
+--+ | = GND
+--+--+-----+---+
| 40 39 20 34+--<=R2=>-+--+5v
| 31+--<=R3=>-+--+5v
| | +5v
| | +-----------+ |
| 38+--------------+3 14+--------+
| 37+--------------+6 Z4 7+---+-++-+
| 36+--------------+8 | | C5
| Z1 10+--------------+11 | | J1 (25 pin DB)
| | | 1489 | Gnd +----+
| | nc-+2 1+------------o--+ 8 |-CD
| | nc-+5 4+------------o--+ 6 |-DSR
| | nc-+9 10+------------o--+ 5 |-CTS
| 8250A | nc-+12 13+------------o--+ 3 |-RX DATA
| | +-----------+ +--o--+ 7 |-GROUND
| | | | | +----
-
| | Shield Ground------+ - =--o--| | ++-- -
| | +5v +-----------+ +------o--+ 1 +--+
| | | | 6+------------o--+ 20 |-DTR
| | +----+5 Z3 8+------------o--+ 4 |-RTS
| | +----+10 11+------------o--+ 2 |-TX DATA
| | +----+13 3+-nc +----+
| | | 1488 |
| | nc-+2 |
| 33+--------------+4 14+----------------+- +12v
| 32+--------------+9 1+--------+ |
| 11+--------------+12 7+---+-++-+- -12v |
+---------------+ +-----------+ | |
+-------++---+
| C3
= C4
25 vs 9 pin DB connectors
J1 (25 pin DB) (only for a 9 pin DB)
+----+ +----+
o--+ 8 | CD {Carrier Detect} + 1 |
o--+ 6 | DSR {Data Set Ready} + 6 |
o--+ 5 | CTS {Clear To Send} + 8 |
o--+ 3 | RX DATA {Received Data} + 2 |
o--+ 7 | GROUND {signal ground} + 5 |
| | +----- - | |
(shield ground) | | ++--- - {cable shield cover} | |
+----------o--+ 1 +--+ | |
o--+ 20 | DTR {Data Terminal Ready} + 4 |
1 o--+ 4 | RTS {Request To Send} + 7 |
o--+ 2 | TX DATA {Transmitted Data} + 3 |
+----+ +----+
3 wires are external to the card
(shield may not be needed) The shield can be connected with a mico-clip
on a 5 inch wire to either of the two stake pins at the rear of the
modem.
+--------------------+ +12v (from A15 on modem edge connector)
|internal modem |
|component side |
| ++x | pins B15-B1 on reverse side
+--------------++x---+
A15 A1
2
This 4 inch wire should be soldered in place.
+----------------+
|power supply | -12/-6v (from A10 on PWR supply board edge connector)
|component side |
| ++x ++ no pins on reverse side
+----------++x--+
A10 A1 This should be a 12 inch wire with a micro-clip to
3 connect to a component soldered into the -12/-6v
trace.
Test that +5v +12v GND and -6/-12v are not shorted to anything else! Go
back and verify all wiring with your meter. Then verify the voltages at
the IC sockets before installing the ICs.
The two 40 pin sockets and the modem board socket must be the type that
grip from the side, not front & back. The contacts are plainly visible
on these. This type socket also has legs exactly like an IC to fit the
modem board socket.
Some mice such as the Genius Mouse require -12v and will only work with
the 70 v.a. power brick and full length board. Most JRs have the 50
v.a. power brick and short board which delivers -6 volts.
|\ +----------------------------------------+
| | /=== 1489 1488 +------------------+|
| +-- ---+ === +-----+ +-----+ | 8250A ||
| +--- --+ === +-----+ +-----+ | ||
| | \=== 1 1 1+------------------+|
|/ +----------------------------------------+
+------------------+ -8250A IC
+-----+ +------------------+
====+ +-----+ +------------------+ -40 pin wirewrap socket
soldered in PC board
/\
(pins 10 11 31-34 36-39 are cut flush with the board,
the remaining pins are cut about 1/4" long to insert into a socket)
+------------------+
+------------------+ -40 pin socket
+------------------+
+------------------+ -40 pin socket
/\
(the two side contact sockets prevent damage to the modem board
socket and provide component clearance)
+------------------+ -modem bd. 40 pin socket
+----------+
|Parts List| Radio Shack part#
+----------+
1 PC board 276-192 4.99
(only a small section of board is needed)
(parts can be found discounted; my total was $12.50)
1 1488 IC 276-2520 1.29
1 1489 IC 276-2521 1.29
2 14 pin sockets 276-1999 .89
2 40 pin sockets 276-1996 1.98 (2 @ .99)
1 40 pin wirewrap socket 276-1984 1.99
2 10k resistors 271-1335 .39 3 extra
3 .1mf capacitors 272-109 1.79 2 extra
1 DB25 male connector 276-1547 1.49
1 DB25 hood 276-1520 1.79
1 pair micro clips 270-336 1.19
9 conductor SHLD cable 278-775 .59 per ft.
======
total $ 19.67
(The 276-192 PC board could also be used to replace the modem
if you're up to the extra wiring or cost of an 8250A)
Note: The user assumes all risks and liabilities!
Many thanks to Michael Hackett and Paul Berger for their
Instructions to Build a Serial Port (modem replacement). The
IBM PCjr Technical Reference is also a good source of information.
--- msged 1.999
* Origin: WOC'n our BIONIC DOG in Newton, MA 617/964-8069 (1:101/138)
SEEN-BY: 13/13 104/904 115/212 147/7 46 49 396/1
