@retrochallenge – Magic Smoke And Serial Ports

January 16, 2012January 17, 2012Retrocosm Leave a comment

I’ve been trying out the expansion units that came with the 5140 and clip on to the back of the main machine. One provides parallel and serial ports and the other is for connecting a monitor. Unfortunately I had a ‘magic smoke’ incident with the later unit after powering up the machine. It was a bit of an ‘oh shit’ moment as initially I didn’t notice it but caught a whiff of the tell tale stench before spotting the smoke rising from the unit and shutting it down. I haven’t opened it up yet to see what the damage is but hopefully it’s repairable.

Expansion Bus Connector

The expansion bus on the 5140 uses 8-bit ISA architecture. At the rear of the unit is a single 72 pin edge connector which is repeated on the back of each expansion unit. Once attached the expansion units give the machine a very odd look, especially if you also attach the printer unit which results in the 5140 almost doubling in length.

Theoretically you could create some kind of hack with an old unit and hook up an HDD but that’s well beyond my level of tinkering.

Serial/Parallel Expansion Unit

The serial port on the interface expansion unit is working. I downloaded the ever dependable Kermit and after stripping it somewhat to fit onto a 720k floppy loaded it up and dialled out to my BBS and sent off a couple of emails. It’s been interesting running a machine with no fixed disk. The second drive by the way has started working, maybe whatever was preventing it from reading disks before has been dislodged. I made a quick video of the 5140 below:-

I also found the following advert for the 5140 on Youtube, in it you can see the machine hooked up to a monitor, I lust after that monitor, I want one, a lot:-

@retrochallenge – IBM 5140 Convertible

January 14, 2012January 14, 2012Retrocosm 3 Comments

I’ve taken a break from playing with the Samsung PenMaster and thought I’d take another crack at getting my IBM 5140 up and running. When I originally plugged it in, the power supply fizzled for a while and then went pop and as I have been unable to source a suitable replacement the machine has languished in storage since.

IBM 5140 Closed

It occurred to me a few days ago as I was wiring the PenMaster up to the new bench top power supply I’d purchased that I could of course use it to power the 5140. The power connector for the IBM has a 5.5mm diameter plug with a 2.5mm centre. I checked online and confirmed that the centre pin is positive so I cut off the cable from the fried power supply, checked which wire was which with a meter and hooked it up to the bench top PS.

The 5140 requires 15v DC at 2.7 amps to both run and charge the battery at the same time. The battery looks as though it’s had a leak in the past so I’d already removed it but wasn’t sure if the 5140 would run with it disconnected. Fortunately it turns out that it does as on power up it POSTed and after querying both drives which were empty dropped into the default BASIC.

IBM Startup Diskettes

The unit came with a wallet containing PC DOS 3.30 on both 3.5 and 5.25″ disks so I restarted with the relevant disk in drive A and the machine booted successfully to DOS. Drive B is not currently working although I suspect it’s just a cleaning job.

Both drives are 720k units and pop up for access as you open the lid. Incidentally this was the first IBM machine to use 3.5″ drives, the first to run on batteries and the first to use surface mount technology. The 80×25 LCD screen on my example is unfortunately not backlit as found on later models and is almost identical to the one found on the Epson PX-16 and similarly lacking in contrast.

IBM 5140 Convertible

The CPU is an Intel 80C88 running at 4.77 MHz, there’s 512 KB of RAM and no HDD nor room for one. There is space inside for an optional modem although mine doesn’t have one and other expansion comes courtesy of units which have to be clipped on at the back.

I have two expansion units, one provides a serial and parallel port and the other is I believe for connecting a CRT. The existing LCD is removed by simply pushing the bottom of the square panel below it which tips forward and allows the screen to be lifted off, the idea being that the unit quickly converts from a portable to desktop.

Serial & Parallel Expansion Unit

Targets are to try to get the second drive working hopefully with a simple head clean and then to try out the expansion units by connecting a modem to the serial port, possibly a printer to the parallel port and then see if I can get a video signal from the other expansion unit.

Screen Removed

@retrochallenge – Changing Direction?

January 8, 2012January 8, 2012Retrocosm Leave a comment

Samsung PenMaster

I’ve managed to free up 7-8 MB of space on the PenMaster’s internal HDD without breaking anything. This has allowed me to successfully install Internet Explorer 3.02. Well I say successfully, although the package has installed, I was under the impression that it contained a TCP/IP stack and dialer software but this doesn’t appear to be the case. I had a look around and found Trumpet Winsock which I remember using with the Amiga 1200 when I first connected to the Internet back in I believe 1991. Funnily enough, the ISP I was using then, Demon Internet, are still hosting the file on their FTP server here.

I shall attempt to install this and see where it leads. If I’m honest I’m not feeling the retro lurve for the Samsung, whether it’s because it’s not quite old enough or possibly because it hasn’t actually provided much of a challenge in terms of getting it working I’m not sure, most likely a combination of both.

I may therefore change direction and look at something else from my growing pile of gear. I have a non-working IBM 5140 convertible which I may try to resurrect, it’s quite a unique machine on a number of levels so it would certainly be interesting to have it working.

Also it’s looking as though I’m going to have less free time this month than I’d hoped so fingers crossed I can get something else done.