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MiniSport Laptop Hacker 07
MiniSport Laptop Hacker - Vol 7 20 Feb 93
Thanks to W4NTG, N7SXD, KD7HP, and others who have given me feedback the
last few weeks. I've been hot and heavy into getting TPK1.80 (automated
mail drop on my local computer) up and running.
>>> ADMINISTRATIVE
My packet address remains the same, but notice that my Internet address has
changed (it's now jupiter rather than visual). Does anybody have a recent
callbook? Is my address correct in the 1993 Callbook? 6006-B Eaker, Fair-
child, WA 99011 is the correct address. Send me packets, e-mail, or US
Mail. I need ideas, questions, and answers!
The local sysops have frowned on sending back issues through the packet
network. If you need some back issues, please send me a disk, postage &
mailer to get it to you. In addition, I've got word back that a 7k
packet message is too much. I will try to keep them to one page (but
there's so much good stuff!). What format would you like them in? 80 col-
umns is ok? 75 columns? Do you print at 6 lpi or 8 lpi?
>>> COMMUNICATION
I just came across an easy circuit that lets you wire up bidirectional
transfers with a parallel port. I need to look at that one a little bit &
talk about it in an upcoming issue. Has anybody else seen this done?
But for now, let me pass on some serial port information. Buried inside
your ML is a more advanced chip that appears like an 8250 programmable
UART. Eight consecutive addresses are taken by the chip for each communi-
cation channel. For those of you who are unfamiliar with this concept, let
me repeat: Each "port" on your IBM/PC compatible really takes up eight
consecutive addresses. All addresses are used by comm software. On the ML
there are two blocks of eight addresses: COM1 and COM2. Following is a
chart introducing the organization of these powerful I/O chips. For exam-
ple, if you want to check on the CTS, DSR, and RI of COM1, you could read
in the Modem Status Register at address 0x03FE (hexadecimal). Bits 4,5 and
6 would give you the condition of the desired lines.
DLAB A2 A1 A0 8-bit Register Name
--------------------------------------------------------------
0 0 0 0 Rcvr buffer (RBR), or Txmtr buffer (THR)
0 0 0 1 Interrupt Enable (IER)
x 0 1 0 Interrupt Identification (read only) (IIR)
x 0 1 1 Line Control (LCR)
x 1 0 0 Modem Control (MCR)
x 1 0 1 Line Status (LSR)
x 1 1 0 Modem Status (MSR)
x 1 1 1 --- nothing ---
1 0 0 0 Baud Rate Divisor latch LSB (DLLS)
1 0 0 1 Baud Rate Divisor latch MSB (DLMS)
--------------------------------------------------------------
Note: A2-A0 are the three LSB of a IBM/PC "COM" port address,
e.g., the MCR (offset of 4) for COM2 (02f8) is available on
a IBM/PC platform at address 02fc). DLAB is the MSB of the LCR.
On any PC compatible, the following addresses are in effect:
Register COM1 COM2
-------------------------
RBR & THR | 03F8 02F8
IER | 03F9 02F9
IIR | 03FA 02FA
LCR | 03FB 02FB
MCR | 03FC 02FC
LSR | 03FD 02FD
MSR | 03FE 02FE
- |
DLLS | 03F8 02F8
DLMS | 03F9 02F9
End of my page. Continued next time...
>>> UPCOMING
MORE 8250 DOCS, SERIAL & PARALLEL BUFFER CHIP PINOUTS, COM2 PINOUT, Poor
Man's Packet INSIDE YOUR MINISPORT, SHRINKING YOUR FAVORITE SOFTWARE, MINI-
MUM BOOT FILES, BOARD REVISIONS, and more DISASSEMBLY.
73, Brian, ka9snf@wb7nnf.#spokn.wa or Internet ka9snf@jupiter.spk.wa
