The Fitting Room
ThiNGS ThAT Go KAbooM IN ThE NiGhT
ThiNGS ThAT Go KAbooM IN ThE NiGhT
Mike Jewison, AC Staff Columnist
What Goes Around Comes Around
Way back in the first issue of AC I discussed this (sometimes) annoying habit I have of never throwing anything away. Our illustrious Managing Editor has referred to this trait as some sort of "Packrat Syndrome". I tend to oppose that description, however, as I think of packrats as people who never throw anything away; I, at least, try to purge my file folders at least once a decade. I like to think of myself as more of a... ummm... collector. Yah, that's it, a collector.
Since I became involved in the now infamous mail-in campaign which begot AC, I've discovered an even more insidious side to this habit I have of, uh, collecting things. Something so evil that it enables you to horde volumes without recognizing that you're actually doing it. Something that allows you to stuff note after note into a variety of folders and not take up any physical space. Something which lets you keep hundreds of messages, megabytes of correspondence, at your fingertips. Yup, you guessed it: email!
Now, don't get me wrong, I love email. I use it daily to correspond with both business associates and friends. The problem is that I often have difficulty in letting go; I rarely delete email messages of a personal nature. This has, needless to say, resulted in some pretty large mail folders on my computer at work. I never have a problem with exceeding my disk quota, mind you. As System Manager I can give myself as much disk space as I need. Or want.
Every so often I'll get nostalgic, browse through a number of mail folders and reread what's there. Awhile back I ran across the following from our good friend, the 8-Bit Alchemist:
... I was thinking how uncanny it is that your habits/experiences resemble mine.
- you're a packrat. you hate to throw stuff away, even phone bills from 10 years ago (hey, Packrats Unite!).
- after the novelty of a new toy wears off, you then can't resist the urge to start tinkering with it (ah, a man to warm the cold heart of an Alchemist!)...
Well, I don't consider myself as being quite up to the lofty status of an Alchemist, but the fact that one of their ilk can understand my motivations is enough to give me a warm, fuzzy feeling inside. [Editor's Note. not everyone thinks of The Alchemist as "lofty". There are a few people who consider him a pain in the neck, since he's always finding bugs in everything and is never satisfied, that bony-fingered old goat. Ugly, too! BP]
By now, you're probably wondering what all this has to do with this month's column. Me too. Actually, the truth of the matter is that the novelty of all this nifty hardware I've collected over the past little while has worn off, and I'm unable to resist the urge to start tinkering with it.
RAMDisk Go Bye-Bye
Over the past year I've regaled you with stories on the many upgrades I've made to my 800XL: TransKey, SIO2PC, a cheap 256K memory upgrade, the UltraSpeed+ OS, and a Black Box/Floppy Board combination. One thing that always bothered me has to do with the US+ and my TransKey adapter. For those of you who are unfamiliar with them, the TransKey is a board (from DataQue Software) which enables you to connect an IBM-PC style keyboard to any 8-bit Atari computer. This is the only keyboard I have for my computer; when I purchased the 800XL I bought only the motherboard- no case, no keyboard. The US+ is a replacement OS for the XL/XE computers and is available from Computer Software Services. I've talked about both of these items at great length in previous columns.
One feature of the US+ is the ability to perform a cold boot of the computer without having to power it down. The saving grace of this is that any contents of your RAMdisk won't be lost if your program crashes. To activate this all you need do his hold down the HELP key while you hit RESET. Because I have no stock keyboard for my 800XL I can't do this. All is not lost, though, because the TransKey firmware can emulate a HELP-RESET by a CTRL-F5-DELETE with the PC keyboard. Unfortunately for me, I've never been able to get the CTRL-F5-DELETE to work properly. If my computer crashes, I always end up having to cycle the power. And of course my RAMdisk contents go POOF! No fun at all!
Some time ago, our Moonlight Workshop columnist Jeff McWilliams told me about an enhancement to the TransKey called TKFreeze (which I'll refer to as TKF). TKF is a small homebuilt add-on board which gives you additional control over your computer. It was the brainchild of Michael St. Pierre, the fellow who originally developed TransKey. I retrieved it as an ARC file from the Atari 8-Bit Roundtable on GEnie (#5447 in Library 2), and although I haven't checked it might be available on some of the other online services. There's also an addendum file (#5495) which apparently fixes the TKF circuit for use with XE computers. I haven't actually downloaded this myself.
The ARC file contains two pages of documentation on the theory behind the operation of TKF as well as a circuit diagram and notes on construction. The heart of the TKF is a 4070B CMOS quad XOR gate with buffered outputs, one of which is tied into the GTIA. I won't get into a nuts and bolts description of the circuit; the documentation explains that far better than I.
The TKF boasts two features. The first is a boot delay which can be adjusted anywhere from 0 to 20 seconds. If you have your computer mounted inside a PC case, as I have, and are using a hard drive with everything connected to the PC power supply, increasing the boot delay time will allow your hard drive to spin up before the computer is powered on, thereby eliminating boot errors. The second feature is a special "Freeze-Reset" which is enabled by the SHIFT-ESCAPE-DELETE function of the TransKey. The Freeze-Reset fools the computer into performing a cold boot, again preserving RAMdisk contents. I thought both of these features were extremely useful, so I quickly began the job of collecting the necessary components as outlined in the documentation.
[At this point I have to insert the customary disclaimer that this project shouldn't be attempted by someone who is all thumbs with a soldering iron. Any damage to your computer as a result of this installation is your own responsibility, and besides, you'll most certainly void the warranty on your computer (as if any of us have warranties remaining!).]
The question burning in my mind was how best to install the TKF inside the PC case which houses my 800XL motherboard. There's so much stuff crammed in there already the last thing I wanted was another loose board with a bunch of jumpers between it and the motherboard. The answer was provided by my TransKey. It has a small daughterboard which plugs directly into the POKEY socket into which you then plug the POKEY chip. I always thought that was a neat way of doing things, so I decided to construct my TKF in the same manner. Since the TKF makes use of several connections on the GTIA I decided to build it on a small printed circuit board, plug that board into the GTIA socket, and then stick the GTIA into the TKF board.
For the circuit board I selected a small general purpose Radio Shack IC board (#276-150). I cannibalized a couple of Augat chip sockets to remove the pins and soldered them in two rows of 20 on the IC board to hold the GTIA. Since the holes on the IC board were slightly too small for the pins, I had to use a small drill to enlarge them. The pins protrude well below the underside of the board giving plenty of clearance between it and the motherboard.
I then installed a socket for the 4070 as well as the rest of the components on the TKF circuit board. The +5V and ground signals on the TKF board are taken from pins on the GTIA. Once I'd finished the soldering, I checked and rechecked my wiring, plugged the GTIA into the TKF board, wired in the jumpers between the TKF, TransKey, and 800XL, stuck the TKF board into the GTIA socket and powered everything up.
Solid gold. That's not how it performed, that was the color on my monitor screen. I knew power was getting to the computer since the CAPS LOCK light on my PC keyboard was blazing away, but all the monitor showed was this very pretty gold color. I sighed deeply, powered the computer down, and checked everything on the TKF board: GTIA, empty 14-pin socket, external connections, everything OKwups! Hey, wait a minute- empty 14-pin socket? Ah, stupid me, I'd forgotten to install the 4070. So I stuck the 4070 into its socket and powered the XL up again. Within a second, I saw a red flash from the underside of my TKF board and got a faint whiff of that acrid smell which tells you: BURNING CIRCUITS!
I never moved as fast in my life as I did when I hit the switch to cut power to the computer. With tears in my eyes, I pulled the TKF from the XL, reconfigured the GTIA as it had been before and tested the XL. I was lucky- there was no apparent damage to the XL- at least none I've been able to detect so far.
My TKF board, however, was another story. The red flash I observed was due to one of the copper traces on the PC board going poof. The trace happened to be the +5V bus. There was close to an inch of the trace which had been blown completely off the board. What happened? Basically it comes down to faulty design and sheer user stupidity. [Dear me, this fellow is really hard on himself. -Ed.]
When I built the TKF board, many of the components (including the socket for the 4070) were positioned above several small ICs located just to the rear of the GTIA. It appears that when I inserted the 4070 into its socket on the TKF board I pushed the board hard enough to cause one or more solder joints on the underside of the TKF board to come into contact with one or more pins on the chips near the GTIA, creating a short. That was the faulty design; I should have built the board such that the components were positioned over the empty space to the left and front of the GTIA. The stupid part was that although I must have checked the circuit a dozen times before installing the board I somehow reversed the +5V and ground buses. Little wonder the whole thing went kablooey; the really amazing part was that nothing else was damaged.
I was back to Square One. I redesigned the board, and in the process ended up with a much cleaner circuit than the original; fewer jumpers and far fewer crossed wires. This time, construction and installation went flawlessly. I even remembered to install the 4070. I flipped on the power supply in the PC case, and after an anxious 8-second wait the computer jumped to life.
The user delay circuit on the TKF is adjustable with a trim pot on the board. I adjusted the delay down to about two seconds. This gives the IBM key board I'm using with the TransKey time to go through its power-on self test (POST) before the computer comes up. This allows me to hold down OPTION to disable BASIC or, if I wanted to, I could even load a boot tape by holding down START. You can't easily do either of these with a standard TransKey installation.
Going back to our first issue yet again, I originally described the Fitting Room as a place in which you and I would have our computers try various items on for size, just as we might in a clothing store. One of the most important aspects of a clothing purchase (at least, so I'm told by my wife) is the coordinating of accessories. We're going to do a little of that here.
I have a Black Box (also from Computer Software Services) which resides with my 800XL motherboard inside an old flip-top style IBM PC/AT case. My Technika MJ-10 monitor sits atop the case, making it a tedious chore to open the case if I want to get at something inside. The Black Box (BB) sports two pushbuttons: one brings up the BB menu, the other dumps contents of screen RAM to your printer. The problem is obvious, isn't it? If I want to get into the BB menu, I've got to move the monitor, flip open the case, press the button, close the case, and replace the monitor. Ugh! It turns out the TransKey firmware can greatly simplify this procedure.
The TransKey documentation (V2.0) describes a number of special keys and how to implement them. By wiring pin #1 of J3 on the TransKey main board to the center terminal of the BB menu pushbutton, you can enter the BB menu by pressing CTRL-SHIFT-5 (on the NumPad). By similarly connecting pin #2 of J3 to the center terminal of the BB screen dump pushbutton you can send the screen contents to the printer by pressing CTRL-PRINT SCREEN. Excited by the prospects of having access to these BB functions from the keyboard, I wired a couple of jumpers into place. I used a small 2-pin molex plug to connect the jumpers between the BB and TransKey just in case I want to remove either for some reason; I won't need to break out the soldering iron.
Both functions work exquisitely. I've since closed up the PC case and plopped the monitor back on top. The only time I need to go inside the case now is to work on another hack.
What's Up, Docs?
The only nit I have to pick about this deals with the TransKey documentation. When I purchased my TransKey roughly two years ago, I received an older copy of the docs which didn't mention either of these useful functions. This was right around the time when DataQue Software purchased the rights to TransKey from MicroSolutions, and there was a note in my docs bemoaning some files "lost" in the transfer. I hope Chuck Steinman of DataQue has had an opportunity to upgrade the TransKey docs. It would be a shame if other TransKey users weren't aware of some of the powerful features it offers.
That pretty much wraps things up for this month. Next time we're going to get away from hardware and try out some software for a change. See you then!