LOCK keyboard port SPECCY
When connecting CDOS-MODEM
Write this article I have decided after
how for months to no avail
tried to connect to your computer
"Compact-128" Ming CDOS-modem. Now
Yet this problem is successfully solved by
an unpretentious device which invented our Homel hard'er SSSR,
for which I am immensely grateful to him.
Actually, I am a person very far from
iron, so when I ran into similar glitches, I had to resort to
by an electronics professional.
One problem is that on my "compact", which is widely
distributed in Gomel, as well as on some other computers, due
to not fully thought out circuitry there is a conflict between
the port of the keyboard and an external device such as a
modem. All ports are either busy or they hang the keyboard. In
An external device can not be
select programmatically, for example,
terminalka EMS just hangs instead of giving the port number
"--".
Let us approach this issue from the perspective of
zhelezyachnika. At first glance, nothing here
No complicated: to connect the modem, as well as
and other external device is quite simple: look for free ports,
according to the concept of routing bus company Dunn & Solder
findings according to the signals scheme to the system
connector, or directly on the processor.
Just in case, bring raspayku findings modem developed ARS'om.
The first conclusion is marked on the board, "1".
01 - D7 (Data Bus);
02 - +5 V (power);
03 - D6 (data bus);
04 - D4 (data bus);
05 - D5 (data bus);
06 - GND (housing);
2007 - WR (write);
08 - RD (read);
2009 - IORQ (IO);
1910 - A4 (if the port # EF);
In total there are few standard
ports for connecting CDOS-modem:
# EF (239) - the most widely used.
# F3 (243) - for "byte";
# 77 (119) - for "GRM";
Find a free port is very easy. Enough of any type the following
BASIC combination: PRINT IN N; where the N-port
in the decimal system. If, after
all this pain and you will see on the screen
255 - that seems to be all right -
port is available. However, do not hurry to be happy we must
also check the port on the record. This You can do the feeding
team: OUT N, M, - where N-decimal port number, and M-any
number (0,1,255, etc.). If, in addition to
computer there is nothing strange: the type of discoloration of
the curb, squeak in dynamics, etc., can congratulate yourself -
port is really free and can be safely
hang on him the modem. Otherwise,
This port is addressed as # FE and want to
or to seek other free ports, or,
if none is found - to tighten
decoding ports (two bits):
A 0 <1 '
A1 <2
A2 <3
A3 <4 to 9-foot chip th
A5 <5 80> 555LL1 (DD1.3)
A6 <6 modem.
A7 <* 11
12 555LA2
However, in my "compact" is not a panacea, because then
begins to "puff brains "kempston joystick, and the data bus
clogged, which leads to various bugs and
Trouble.
Of course, this can be cut off kempston
completely, as it did from the KVA
Grodno, in its "CD-128", and put
tumbler. We called the KVA and asked to help with the scheme of
improvements and new driver for EMS. Victor promised to send
shemku by regular mail and by Fido, however, two
months we have not received anything from him, in spite of our
constant calls and requests. So we had to use the old,
well-proven method of educated bet.
And this button is done as follows:
D24 (K555KP11) D25
> KB0 02> KB4 2
> KB1 05> KB5 5
> KB2 November 2004 D0> IN November 2004
> KB3 July 14 D1> KB7 July 14
> DV0 March 2009 D2> DV4 March 2009
> DV1 June 1912 June 1912 D3
> DV2 10 * 10
> DV3 13 13
> X 01> x 1
A0 1915 A0 1915
-IORD0-IORD0
We are looking at the board, "Compact two chips
D24 and D25 (K555KP11). Cutting the Track
leading to the first two legs of the chips from
Contact A0 and throw released the first leg to the body. The
result - Kempston no more, no test program
Now you will not find it. Immediately begin to work normally
"ZX-ELEMENT-1" where before the cursor was constantly activated
and some other programs.
Tumbler set to cut the chain: from A0 to
findings "01" chips. You can do this
use any two-position switch, such as "mikrikah.
But you must agree, this is somewhat
inconvenient - to hang an extra switch,
and then automatically shut off when kempston
work with EMS, MMD, CDOS and the like.
And here, in the head SSSR comes a brilliant idea - to put
an ordinary inverter transistor, a blocking read the keyboard
port (# FE), in order to prevent selection of ports, when
queried by a modem.
Collect elementary shemku:
By __ +5 B
/
____ B | / KT315 (n-p-n)
<_ \ \ _ | <-----------
1K | \ E
to the modem: takes \ _____ to 15 feet
value "1" if it is both chips
selected. D24, D25 on the signal
signal - IRD0.
If an external device, through the transistor keyboard port
is blocked and no longer prevents the poll the same modem.
Feel free to hang up the modem to the port (# EF) and work on
health in the EMS, MMD and CDOS.
Now there is no need to install the switch - blocking is
automatic and completely transparent for the user. No side
effects this transformation in the "Compact" does not call.
On computers with the correct choice
ports, for example, in the company, "Scorpio"
This revision is necessary.
Thank you very much hard'ery SSSR for the great idea and
help in connecting my modem.
