How do you use a computer that's 30 years old, has no monitor, and no keyboard?

http://www.reenigne.org/blog/i-bought-an-xt/

by sbierwagen • 15 years ago

71 21 15 years ago

shabble• 15 years ago

Sounds like the beginning of a beautiful hack. The keyboard-interface as I/O reminds me a lot of the similarly awesome ipod firmware dump via piezo speaker: http://web.archive.org/web/20070613032334/http://ipodlinux.o...

ajenner6• 15 years ago

A little update - I've now replaced the power supply's circuit board with one from a modern (and working) ATX PSU, the graphics card with a CGA card (which works with the TV with the BIOS timings) and booted into ROM BASIC using a little Windows program to turn keystrokes into scancodes sent over the serial port.

The hard drive doesn't appear to be bootable and I don't have any floppy disks for it yet so I need to write some more code to see if the hard disk is broken or just doesn't have a boot sector, and to determine which RAM chip is faulty (it's only detecting 192Kb of the 256Kb onboard RAM).

amorphid• 15 years ago

In case you don't know, a 9 pin serial port looks like a CGA port. I distinctly remember learning that the hard way as white smoke poured out of the power supply :)

smoyer3• 15 years ago

It doesn't look like a CGA port ... the serial port is male and the CGA port is female (as are early VGA ports as well as the Hercules Monochrome port). Some of the XT's had DB-25 serial ports (the DB-9 serial ports were introducted with the AT) DB-25 parallel ports (so you could drive your Centronics printer).

ars• 15 years ago

I'm pretty sure I have somewhere a floppy for changing the bios settings of those machines.

Perhaps a different machine, I'll have to check.

I have no way to read the floppy, but it has to exist somewhere on the internet.

ajenner6• 15 years ago

These machines are so old they don't even have a real time clock, let alone any CMOS RAM on the motherboard. You change the BIOS settings by flipping physical switches, and DOS would prompt you to set the time and date on every boot!

This particular machine does have a clock on a "Tecmar Captain 200044" expansion board - if you have a manual or software for that I'd be very interested. I've found no information about it on the internet (other than people selling them, so it must have been fairly popular at one point).

smoyer3• 15 years ago

Would you like an XT keyboard ... I found a box of them in my basement recently.

ajenner6• 15 years ago

That would be great! My email address is andrew@reenigne.org.

steve8918• 15 years ago

Ahhhh, memories!

The first computer I had was an 8088 XT clone with a turbo setting that went from 4.77 MHz to 8 MHz! It was blazing fast!

I remember the very first thing I did when we brought the computer home from the computer store was I went through the hard drive and saw this file that I couldn't possibly use, and deleted it. Why? Who knows, I was a dumb kid.

Yes, you guessed it. COMMAND.COM.

When I rebooted my computer, I got the "COULD NOT LOAD COMMAND.COM" error and I freaked out because I f'ed up my computer on the very first day I had it and my parents would kill me. I knew I could boot from my DOS 3.2.1 diskettes, but not from my hard drive, so after straining, I somehow managed to figure out how to copy the command.com from my diskette onto my hard drive and it worked.

And thus started my illustrious career in debugging computer problems and IT support, which continues to this day.

Luyt• 15 years ago

On a slow day, you could TYPE C:/COMMAND.COM and watch all the gibberish fly by, with the occasional beep due to the BELL character.

ajenner6• 15 years ago

Heh, I used to do that with all the binaries I could find in an attempt to learn their secrets (before I discovered I could do it with DEBUG.COM). I found that doing "copy command.com /b con" would show me more since it would stop on EOF characters.

jamesbkel• 15 years ago

Have some similar memories myself. Definitely learned a lot from being a little too enthusiastic about modifying files/settings on the family computer.

What stands out for me is the period when I was still just a kid, albeit the "neighborhood computer kid". I'd inevitably get a call every few weeks from someone who lived nearby or was a friend of my parents. I'd go over, almost always figure out the problem and then they would ask "How did you know to do that?". I'd explain what happened best I could, but I'd be thinking to myself, "How did I know to do that? Well, I didn't until now."

Also, it was pretty cool at 11 years old to discover that I could make money just by working on my own to help other people folks fix problems and didn't necessarily need a "real" job.

ck2• 15 years ago

You can still get the large 5pin din connecting keyboards on ebay. Search for "G83-6414" for example.

But I think the 5pin to ps/2 connector may just be a straight wire through to the smaller connector, so you can reverse that?

Threw out turbo-xt motherboards well over a decade ago.

Still have a couple 16mhz 386sx motherboards somewhere that I cannot seem to make myself throw out because they worked fine, just (very, very) outdated. They are so tiny (1/3 board size) that they don't take any space to keep around.

Also have some isa vga cards somewhere - could send you one if you really needed. But the original XT also had an optional color card with composite out that could still be easily used today.

ajross• 15 years ago

My memory is that the AT (and PS/2) keyboards shared the same signaling, but had different scan codes. So it wouldn't work to plug a PS/2 keyboard in via a DIY adapter.

ajenner6• 15 years ago

Different scancodes and different protocol - there's plans for a microcontroller-based adapter at http://www.vintage-computer.com/vcforum/showthread.php?15907... .

DanBC• 15 years ago

I love to see this level of investigation. It's a great shame that there's not really any programme of funding or support to encourage hacking like this. Hopefully people will dig around in cupboards / attics / basements to find more hardware.

hackermom• 15 years ago

By serial terminal, was my first thought.

jff• 15 years ago

That's how I access my 30-year-old PDP-11 with no monitor and no keyboard...

ajenner6• 15 years ago

That was my first thought too, and I made up serial and parallel cables. But without a keyboard or disk drives, there's no way to bootstrap it into running some software that will talk to the serial or parallel port.

Roboprog• 15 years ago

Ah, but there is. As one of the commenters on the site noted, you make a floppy with the redirection command in "autoexec.bat". Of course, I only have a 3.5 inch USB floppy drive, but not a way to work on 5.25 inch floppies (no sure if spare drive in garage still plugs into anything in newer mobos)

How do you use a computer that's 30 years old, has no monitor, and no keyboard?

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