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MiniSport Laptop Hacker 01
MiniSport Laptop Hacker - Vol 1
As some of you may know, Zenith has gotten out of the business of selling
personal computers. I had the good fortune to purchase some of their ex-
tremely small MiniSport laptop computers. They are absolutely perfect for
packet use and in any RACES or ARES setup, they could provide other func-
tions as backups due to their universal hardware platform. I thought oth-
ers might be interested in information I've collected in case you're using
one or interested in buying one.
If *you* have information, please pass it on to me. I'll bundle it up and
send out a MiniSport Laptop Hacker Part 2!
These computers are basically an IBM/PC platform with 1 or 2 Mbytes of RAM,
MSDOS 3.3 in ROM, a 2" floppy, and a 25x80 column LCD screen. RAM above
640k can be used for EMS or battery backed RamDrive. They have connections
for an external CGA monitor, an external floppy, serial port(s), and a par-
allel port. Primary connection to other computers is via a 3-wire or 7-
wire (faster baud rates) null-modem cable. FastWireLink program is includ-
ed in ROM with MSDOS, logically on drive C:
The 2" disks are hard to locate, but I finally found a source for them,
albeit an expensive and un-friendly one: Rex Television Service Co., phone
708-448-5558.
I had a power supply problem with one. I unscrewed the case and innards of
the offending unit and learned a lot. The interior is modular and easy to
work on: Power supply, Main CPU board, Keyboard, Disk Drive, and LCD dis-
play. Multiconductor ribbons connect the parts. If you open yours up and
slide the main PC board out, be carefull of the POWER SWITCH and the disk
drive EJECT BUTTON. Both get caught easy on the case and might snap some-
thing. The only tricky part is that one of the drive mounting screws needs
to be unscrewed before you can release a thin piece of copper ("Mu metal")
colored grounding strap wrapped up and around the main PC board from below.
Like I said, I had a power supply problem with one. To the best of my
knowledge, it's an intermittent cable contact. Each time it fails, uncon-
necting & reconnecting the one PS cable fixes the problem. It's a 15 min
operation and is not complicated. I'm thinking of swapping power supplies
around. I have the pinout of the PS connection to the main board, if you-
're interested. You could test the PS by only taking off the bottom com-
puter panel and measuring voltages from the "underside" of the circuit
board.
The unit is powered by a removable battery that reminds me of a cam-corder
battery. It's advertised to be 6v. I suspect it's five NiCd cells (5x1.2
=> 6.0). The computers power supply/ charging receptacle is on the battery
pack and feeds connections further into the computer. I've tapped into the
wierd shaped connector with paper clips. Alternately one could bypassed
the battery entirely by clipping alligator clips onto the sliding contacts
on the computer. The batteries will charge with a 6volt supply, but the
computer runs from 9volts DC if it's not using batteries.
As I hinted above, a second serial port is available. It's logically
there, but terminates mechanically in a Scotch-Flex type socket. It's
meant to accept a modem module. I'm currently trying to determine a pinout
for this connector. If you have the information already, perhaps you could
pass it on to me.
The external floppy drive connector has been as difficult to find as the 2"
floppy disks. It is a square outer connector, with a female D-shaped re-
ceptacle. The D-shaped receptacle has 20 pins. It's just under 3/16" tall
and just under 5/8" wide (at the wider side of the D). If you have any
PINOUT OR ACQUISITION INFORMATION for this type of connector, please send
me a message and I'll include the information in round 2 of the MiniSport
Laptop Hacker.
73, Brian, ka9snf @wb7nnf.#spokn.wa.usa
