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MiniSport Laptop Hacker 19
MiniSport Laptop Hacker - Vol 19. Jan 1994
To discourage pecuniary interests, Copyright (c) 1993 Brian Mork
>>> ADMIN
Remember, you can get copies on disk of any software or text file I re-
fer to (including the MLHacker series) by sending me a disk and SASE.
I'll put a variety of other MLHacker related goodies on there, too.
Alternately, you may make a direct call to the data number listed below.
In this case, use the FILES command, and L)og into the \public\computer
directory.
MLHacker is starting to show up on some Internet servers. Ask around or
you can offer to upload it for me to your nearest host.
>>> PARALLEL PORT POTENTIAL
The August 1993 (Issue #37) issue of Circuit Cellar INK has a six page
article describing how to turn the PC parallel port into a powerful TTL
input/output port, even if it's inherently only an output port (prior to
the proliferation of PS/2 compatible bidirectional parallel ports). The
circuit uses only five chips: 2x 74LS374, 2x 74LS244, and 1x 74LS138. I
will eventually build one and report on some fun things to do with it,
but in the meantime, I thought I'd give a pointer to the article to oth-
ers in the crowd who could use this capability now.
>>> 2ND MEGABYTE ADDITIONS
Thanks to Griff, Troy, and Jeff. Each has experimented around with the
empty sockets in ZL-1s that hold a second megabyte of memory in ZL-2s.
Bottom line is that you can add a standard IBM PC SIPP (1Mx9) or a Mac-
Intosh type (1Mx8) memory package. If you have SIMMs, you'll have to
add some pins, and in some cases, trim the circuit board card to fit in
side the Minisport case. In all cases, you'll have to bend the package
of memory over sideways after soldering it in. Yea! Anybody have some
spare memory they'd like to sell me? The "old fashioned" slow memory
would work fine in this computer.
>>> PACKET CONVENIENCE UTILITY
I bet most of us use our Minisports for packet at one time or another.
Here's a utility I recently wrote to fix an annoying problem. The com-
puter and the TNC are doing what they're suppose to, but that's not what
I wanted! The limited storage of the Minisport's RAM disk prompted me
to do this one in assembly language. You may have seen it on the nets
as a stand-alone message. As a special addition to MLHacker readers,
the source code is included prior to the text of the other message.
; PK232DMP, initiated Jan 94, BjM (Opus-OVH)
;
XOR AH,AH
MOV AL,1 ; COMx -- put 1,2,3, or 4 here
PUSH AX
ADD AL,030 ; Convert COM number into ASCII
MOV [FILL],AL ; Create output message
POP AX
SUB AL,1
SHL AL,1
MOV BX,AX ; COM address offset into BX
MOV AL,040
MOV ES,AX ; BIOS Data Area Segment
MOV AX,ES:[BX]; Snag COM base from DOS table of addresses
ADD AL,4 ; Generate BASE+ModemControlRegister
MOV DX,AX ; put it into DX
IN AL,DX ; Get existing Modem Control Register
OR AL,3 ; Set DTR and RTS true, and..
OUT DX,AL ; rewrite to hardware
MOV AH,09 ; Select DOS "String->Std Output" function
MOV DX,STRING ; DS set by MSDOS prior to entry
INT 021
MOV AH,04C ; MSDOS Program Termination
INT 021
STRING: DB 'DTR and RTS on COM'
FILL: DB ' set true.$'
Whenever I exited my TNC communication program and did other things with
the computer, my PK232 continued to monitor the airwaves and eventually
the text buffer filled up. At this point, it would accept no new con-
nects to its built-in mailbox, would stop monitoring traffic, and would
log no new callsigns. I wrote this short program to set DTR and RTS
true on the PC compatible COM port connected to my PK232. Now, I exe-
cute the communication program (I use TPK) from within a batch file and
execute this file from the same batch file after the main program ends.
The PK232 thinks the comm program is still monitoring and it continues
to send stuff the computer, keeping its internal buffer empty.
----- cut here -----
e 0100
32 E4 B0 01 50 04 30 A2 3D 01 58 2C 01 D0 E0 8B
e 0110
D8 B0 40 8E C0 26 8B 07 04 04 8B D0 EC 0C 03 EE
e 0120
B4 09 BA 2B 01 CD 21 B4 4C CD 21 44 54 52 20 61
e 0130
6E 64 20 52 54 53 20 6F 6E 20 43 4F 4D 20 20 73
e 0140
65 74 20 74 72 75 65 2E 24
r cx
0049
n pk232dmp.com
w
q
----- cut here -----
Cut out the 15 lines between the "cut here" lines and put them all by
themselves into a file called INPUT.DBG. Use the MSDOS DEBUG program to
generate an executable .COM file using the command:
C:> DEBUG <INPUT.DBG
A bunch of stuff will scroll across the screen. When it finishes, there
will be a 73 byte file called pk232dmp.com in the default directory.
Type "pk232dmp" on the command line to execute this program.
Another COM port may be selected by changing the fourth byte (currently
01) to another COM number, up to 04. For example, if you want to access
COM3, you would change ...E4 B0 01... to ...E4 B0 03... and then run
debug to generate another copy of pk232dmp.com. No provision is made to
accept a command line input of COM port number in order to keep the pro-
gram very small. Perhaps you could make several copies called
dump1.com, dump2.com, etc.
>>> CROSSFLOW
Troy says he has an EPROM burner that he can make copies of ROMs with.
Rather than blithely throwing out his e-mail address, let me know if he
could help you. I'll pass your name on and let him get hold of you. At
least one person has experienced sector errors on disk C: as a result of
the built-in ROM going bad. It's a standard chip, so copying someone
else's and replacing yours should offer no technical trouble. Is any-
body out there brave enough to hack out the format of the ROM disk and
tell me how to replace some of the MSDOS 3.0 distribution files with my
personal files? Now that would be sweet! Power up the Minisport and
have my own programs in ROM. Leaves extra room on the ROM disk, too.
Maybe my next project... after the laser radar. See 'ya next month!
Please provide feedback! * Direct data 1-509-244-9260
* AX.25 KA9SNF@wb7nnf.#spokn.wa.usa
* Internet bmork@opus-ovh.spk.wa.us
73, Brian * 6006-B Eaker, Fairchild, WA 99011
