Tag Archive: PC XT


IRC on my (nearly) 30 year old PC XT

Filed Under: retro
Jan.23, 2012

I recently had the urge to fire up my IBM PC XT.  The challenge usually is to do something interesting on the machine.  Playing games slower than my Libretto 50CT or using Microsoft Word 1.0 is not especially interesting to me but hooking it up to my network and chatting on IRC… that’s more like it.

I have had this thought in the back of my head for a while.  I knew it was possible to put it on a network but finding an 8-bit ethernet card is challenging.  Not only are they super rare but on eBay now they are super expensive.  I’m NOT paying $100 for a network card for a computer I only paid $20 for in the first place.  As a rule, I’ve kept my retro computer hobby cheap so I wasn’t about to make an exception here.

In retro computing, patient generally equals cheap.  This case was no exception.  Someone on one of the IRC channels I hang out on randomly asked me if I wanted another Libretto.  Of course I do!  Any Librettos will find a good home here.  This person graciously sent me not only a nice Libretto 70CT but also a bunch of accessories including a Xircom PE3-10BT pocket ethernet adapter.

This is something I had NO idea existed.  It is an ethernet adapter that hooks up to a parallel port.  It also has a short PS/2 keyboard pass through cable that supplies power since parallel ports don’t have power in their specification.

This left me with two problems on my XT.  First off,the XT has no where to plug in a PS/2 keyboard and second, while I have a parallel port on my AST Six Pack Plus expansion card, the pigtail for it is long gone.  The previous owner probably never installed it in the first place even though MSD(Microsoft Diagnostics) showed that the port was activated.

I poked around online a bit and saw that 8-bit ISA parallel port cards are a whopping $30.  No thanks.  I poked around my garage and found a 16-bit ISA controller card.  This one was just like the 100’s that I installed when I was building clones (as a profession) back in the 386/486 days.  Now I know there is no chance that the IDE bus would work in an 8-bit ISA slot but I thought there was a good chance that the parallel port would work so I jammed the 16-bit ISA controller in the 8-bit card slot and let the extended part of the bus hang over the slot.  I disabled EVERYTHING on the controller except the parallel port.  Lucky enough, I fired up the computer and it showed up in MSD as a bidirectional parallel port.  Yay!!

The next challenge was getting power to it.  I ended up building a very convoluted adapter that went from PS/2 to AT to a hacked midi cable and then to a hard drive Y-cable.  It’s ugly but it works flawlessly.  When I get the proper connectors, I will build something proper.

After that, there was nothing left to do but fire it up and snag the software for it.  First off I needed a packet driver for the Xircom card.  Since Intel bought Xircom many moons ago, they still have the drivers available on their website.  (Xircom PE3 Driver).  So after you unpack the driver, you simply run PE3PD.EXE and it will work if all the hardware is in order.

Second, you need a TCP/IP stack and some applications.  This is solved by the mTCP project.  This project has a DHCP client, Telnet, FTP Client/Server, IRC, Ping, Netcat, an NTP client and a WGET clone of sorts.  One of the most surprising things to me was that this project is still extremely current.  As of this blog post, the last update was October 29th, 2011.  Even if there is never another update though, I’m fairly impressed with what I see.  The IRC client, IRC JR, works flawlessly after you set up the config files which is well documented.

I could use this machine as a terminal for one of my more powerful machines as something mundane like a clock but being able to hook it up and use it as a well-equipped IRC client is fairly pleasing and gives me many more excuses to fire up my XT in the future here.

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How to build an 8-bit IDE controller for a PC XT

Filed Under: electronics, retro
Jul.30, 2010

My final assembled XT-IDE 8-bit ISA card

Once I started messing with my IBM PC XT, I realized that there were things I had taken for granted all along since my first PC compatible system was a 386.  I didn’t realize that IDE uses a 16-bit bus and it would take some trickery to use an IDE device in an older 8-bit system like the XT.  I searched around and found that there were in fact 8-bit ISA controllers but they were expensive and rare.  Finding one these days would be a stroke of luck or a dent in the pocket book.  I was about to design my own when I came across the XT-IDE project.  The XT-IDE project is an open source venture where a group of people designed exactly what I needed with fairly common off-the-shelf parts.  I had my friend James to burn the code onto the eeprom for me  because I have no way to put something on a 360K floppy disc but aside from that, the project primarily consists of easy through-hole soldering.

Front side of the unpopulated XT-IDE PCB

I ordered my board the other day from Andrew Lynch who can be found lurking in this huge forum thread.  It was $14 including shipping which I felt was more than fair considering the quality of the board.  It’s a very professional dual-sided PCB with a full solder mask and silkscreen.  It would take me far too much time to attempt to replicate this at home.  It’s also nice that it has all of the settings printed VERY clearly on the board and the url for www.vintage-computer.com so I won’t forget where I found this project.

The bill of materials looks a little daunting at first but it’s really not a huge project.  The list below references Jameco part numbers.  There are a few non-critical items and some others that you can pillage from other ISA cards such as an L-bracket, pan screws and shorting blocks (jumpers).  I’m personally going to skip using most of the sockets since I’m fairly confident with my soldering skills and dual-wipe sockets tend to add another point of failure.

1               XT-IDE PCB (get this from Andrew lynch)
10   25523 	CAP,MONO,.1uF,50V,20%
1    1945428 	CAP,RADIAL,47uF,35V
2    45129 	IC,74HCT688
1    46316 	IC,74LS04
1    46607 	IC,74LS138
1    47466 	IC,74LS32
1    287144 	IC,74F245,DIP-20
3    282642 	IC,74F573,DIP-20
1    74827     	Atmel EEPROM IC, 28C64
2    112214 	SOCKET,IC,14PIN,DUAL WIPE
6    112248 	SOCKET,IC,DUAL WIPE,20PIN
1    112272 	SOCKET,IC,DUAL WIPE,28PIN
1    526205 	SOCKET,IC,16 PIN,390261-4
3    112432 	SOCKET,SHORTNG BLKS,RED,CLSE
1    690662 	RES,CF,150 OHM,1/4 WATT,5%
6    691104 	RES,CF,10K OHM,1/4 WATT,5%
2    857080 	MOLDED SIP,9PIN,BUSSED,10K,2%
1    333949 	LED,GREEN,572NM,T-1 3/4
1    1939562 	SWITCH,DIP,SPST,8-POS,16-PIN
1    53604 	HEADER,RT MALE,2RW,40 CONT
1    109568 	HEADER,.1 ST MALE,2RW,16PIN
1    109576     HEADER,.1 ST MALE,1RW,3PIN
2    2094389 	SCREW,PAN HEAD,PPN4-40X1/4
1    N/A        Keystone 9202 ISA bracket with 2 PCB mounting tabs.

Once I had all of the parts together, it was time to check out the build instructions.  This project is a VERY easy build.  All of the IC’s are labeled on the PCB, all of the caps are identical except one which is labeled and called out and all of the resistors are the same aside from the one that goes with the LED.  There are only two gotchas that I can think of.  First off, before you solder in the 40 pin IDE connector, you should pull the key pin out from the connector.  Grab an IDE cable and line it up with your connector, you will see which one is the key pin fairly quickly.  Secondly, the default dip switch setting is correct on the back side of the PCB but incorrect in the build instructions.  Set it to 01110111 as stated on the back of the card.  If you need to set this to a different setting, you will need to re-flash the firmware on the eeprom for some reason.  The default seems to work fine however so no big deal.

The original NCL MFM controller that came in my PC XT

Overall this project has cost me about $30.  I’ve learned some new stuff and I can now use my IBM PC XT with a modern IDE hard drive.  My next step will be to try to use the system with a compact flash card.  Now I can install MS-DOS 6.22 and hopefully Xenix at some point without disrupting the original MS-DOS 3.2 file system.

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Sierra On-line Black Cauldron on the IBM PC XT

Filed Under: retro
Jul.04, 2010

I was at the thrift store the other day and scored a copy of Disney’s Black Cauldron game made by Sierra On-line in their glory days of text/mouse based adventure games. When I first got an IBM compatible system back in the 90’s, the Sierra games were by far my favorites.  They were always consistent, always fun and sometimes a challenge to get running properly which was also fun.  This particular game was released in 1985 although this particular copy was printed and sold in 1989.  According to the box, the system requirements are very very low.  It requires 256k of ram, vga, ega, cga or hercules graphics and a keyboard.  Mouse or joystick optional.

I opened up the packaging and was pleasantly surprised to find both the 5.25″ floppies and the 3.5″ floppy.  There were several other goodies inside as well including the manual, the tenth anniversary Sierra catalog and the original Prodigy Network trial offer which brings back many fond memories.  Another prize buried in this box was a hint guide that someone painstakingly downloaded via dial up and printed on a dot matrix printer.

Using a little forensics, it’s obvious to me that this game was played a lot but taken care of meticulously.  The computer it was used was probably late 80’s technology based on the fact the previous user obviously used the 5.25″ disks and most likely played the game straight off of the disk.  There is a characteristic fingerprint/smudge at the top of disk 1 but not on disk two.  I’m guessing the owner played through the game as far as they could get which took them a while.  They probably never made it to disk 2 on their own.  That’s when they resorted to printing the hint guide.  They played through the rest of the game, cheating with the hint guide to beat it in the matter of a couple hours.  After they beat it, they put the game away for 20 years and someone finally donated it to the thrift store.  All of this only leaves one question in mind: Will this game actually work on my PC XT after sitting in a box for 20 years?

Well much to my pleasure, it decided to work!  I put in disk 1 and ran the install script:

install c:

The 30 year old floppy drive sprang to life and copied the disk to the hard drive.  Disk 2 went just as well.  The installer left me in the c:\sierra directory and told me to type:

bc

This is obviously an updated version of the game since the older Sierra games had much cruder install scripts.  Anyhow, I started the game up.  Obnoxious 8-bit PC speaker music came blasting out.  Sad that the IBM’s didn’t even have sound as good as the C64.  I turned the music off with F2 and could then study the glorious 8-bit graphics.  This must have been an amazing game in it’s day.  As far as the sierra line up, I would say the graphics are similar to Space Quest 1, Kings Quest 1, etc.  The game play is much different however.  This game is geared toward younger players so it requires no typing at all.  Instead you use the F-keys to DO, LOOK, USE, etc.  It’s a good concept that Sierra didn’t fully develop until the days of King’s Quest 5, Space Quest 4, etc.

I tend to like both styles of the Sierra games for different reasons.  I plan to play this one through at some point and see what it has to offer.  Go check out Abandonia for much more information, screen shots and a download for the Black Cauldron.

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Dusting off my new old IBM PC XT

Filed Under: retro
Jun.03, 2010

IBM PC XT front view

I was at a computer recycler the other day and there it was… An original IBM XT 8088 system in nearly mint condition.  It was in the front window of “prized” old crap in this store.  I asked the guy if any of that stuff in the window is for sale and he replied, “sure, sometimes it is”.  So then I specified that I was interested in the XT.  He asked what I’d pay for it and I told him $20.  He said, “sure” and it came home in my trunk.  Luckily on the way out the store I noticed the keyboard sitting there.  I asked him if it was cool if I took it and he said it wasn’t a problem.  Later I found out that it’s a good thing I grabbed it because an AT-style keyboard wouldn’t work.

IBM PC XT inside

After bringing it home, brought it out and popped it open to check what was inside.  The system is actually fairly packed.  Someone probably spent $5,000 or so upgrading it to the point it was at.  The memory banks were full and there was an add-on memory card that had a realtime clock as well. Something else I learned was that originally these systems required you to enter the time and date every time you booted them up.  How annoying….  Looking around further, the system has an unmarked graphics card with a printer port.  I would have hoped it was a Hercules but I’m pretty sure it’s not a real one in any event.  There is a 20 megabyte Seagate MFM hard drive and a MFM controller card in there too.  Something else I learned is that IDE pretty much requires a 16-bit data bus to function at all and the 8088 has an 8-bit external bus so it can’t work with IDE without some major trickery so I’m crossing my fingers that the MFM drive still functions.  Lastly, there is a serial port card.

IBM PC XT back

I did plug it in and flip the power on.  Sounds like the hard drive spins up just fine at least.  I’m hoping that it works but I’m currently trying to hunt down an ISA VGA card to test it with.

You may ask why I bothered buying a nearly 30 year old computer.  My original plan was to part it out and build a single board 8088 to learn more about computers but I’ve since changed my mind since this one is in excellent shape.  I have a really cool old book called The 8088 Project Book by Robert Grossblatt.  It goes through the entire process of building up and programming an 8088 based computer on a breadboard.  The picture on the cover is an insane spaghetti mess of wires and breadboards.  Looks like fun but I’m not sure I’m up to the task.

My alternative plan is to use the computer as it sits an attempt to learn some 8088 assembly language in the dos environment.  Might also be fun to try some other operating systems like CP/M or Xenix if I could find copies of them.

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