Hey folks, check out my new tribute site to all things CoCo. Yes indeed the CoCo was the most fun one could have in 8 bits! Site is under construction.
www.cocolives.com
StevCoCo
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I wrote (and re-wrote) my doctoral dissertation on a Coco (I), which was gray, with square? chicklet keys, as I recall. Had to retype, as the ROM pack with the word processor would cause a crash after the connections heated up. Oh, yeah, I saved what I typed on a cassette tape!
To truly appreciate the RS CoCo, you had to program them in assembler. The instruction set is so well laid out in the Motorola 6809E chip it is truly a work of art. A masterpiece of digital electronic design. The Intel 8080 and z80 that powered the IBM PC was a pig in comparison. Bigger word size and faster speed, but still a pig.
My last CoCo had 256K RAM, 2x5.25FDD,a 5" color monitor, and was mounted in a KayProII case. Simply freakin' AWEsome!! Ran (the original) OS/9. Miss them glory days. No better box available until my SunBlade 100 came along.
Did anyone else notice that in the original Terminator movie they scroll 6809 Assemembly code across the Terminator's viewer.
6809 assembly was cool.. It was what I learned on [anyone have a copy of an old assembler called SIGMON?].. After moving to the PC, and having to write some assembler, I was practically CRIPPLED because the assembly was so horribly less efficient! Oh well.. I guess in a world where a terrabyte drive can be bought for under half the original COCO's cost, efficiency isn't the most important trait..
The 6809E was the first 8 bit processor with truly 16 bit internal features. Such as a dual 8 bit accumulator which could be combined into a single 16 bit accumulator register for doing 16 calculations. The 68xx series assembly language addressing modes were much better and simpler then the 808x modes, etc.
I programmed the 6809 in Forth and assembler. I think it's a bit hard, if you put the Z80 and the 8080 into the same pot. I started programming the Z80 on a u-Professor. I don't remember seeing a Z80 in a IBM PC(and compatible). There were CP/M machines from different vendors. My friend had a Sharp MZ-80 for example. I had a homebrewed system with a Eprom burner for storage... One of our programmers at the company i worked then wrote a really neat macro assembler and i got a terminal with a serial interface for free. It survived a fire, but it smelled like a smoking chamber.
Ever since I bought the TRS-80 model 1 I stayed with Tandy product lines, switching to the 4K Tandy CoCo1. When the CoCo2 came out I upgraded, 16K of memory was just too good to pass up. Then the CoCo3 came out with 256K of memory and a few things changed to where older programs and tech wouldn't work on it. I ran a BBS from a CoCo from 1983 to 1991 when the support for the unit was pulled from Tandy and no "CoCo 4" would be hitting the market.
One of the best things it had going for me, was early implementation of being a MIDI controller, and capability of transposing sheet music into MIDI for playback. This predated Cakewalk by years.
One of the best things it had going for me, was early implementation of being a MIDI controller, and capability of transposing sheet music into MIDI for playback. This predated Cakewalk by years.
It's been a couple of decades since I took electronics in college, but the cage around the power supply is most likely a Faraday cage. It's purpose is to contain the electromagnetic disturbances caused by the transformer and thereby protect the electronics elsewhere in the computer from EM disturbances.
This cage is what you say it is - a Faraday shield, or better yet, and Electo-magnetic shield - to keep the strong inductance fields generated by the transformer away from the digital portion of the circuitry.
More from the video circuitry. If you ran the CoCo without that shield, your video display would have an "interesting" swimming effect.
Specifically the CRT. If you were able to hook it up to an LCD, you wouldn't need it. (CRTs use EM deflection to 'write' onto the screen, as it were)
Its secondary function is safety. Inside the cage is 240 VAC ( 110 if you live in deprived areas of the world
Its secondary function is safety. Inside the cage is 240 VAC ( 110 if you live in deprived areas of the world
If you put a monitor close to a unshielded transformer, you won't have a very ergonomic setup. This often happened with plugin power supplies close to the CRT at our customers sites. It seldom happens now with mostly LCD's and switched power supplies. (they use higher frequencies that are easier to shield and less visible on a CRT)
As a former Tandy computer tech I've been bitten by that transformer more than once. I was in the habit of resting my left palm in that corner so that I could locate the power button without looking. With the case off, the shield made it possible to continue that unsafe practice. Woe unto me if I had the shield off to test the connections and wan't paying attention! Resting your palm on a live transformer will definitely wake you up.
during my practical education, i had to repair lots of heating regulators that didn't pass the end tests. (Yes they were analog) With the measuring tip in my hand, my little finger always spread out. And exactly there was the mains connector (220V). On a morning after something like "mardi gras" i touched it 4 times. I asked my supervisor, if it's ok to destroy this particularly nasty regulator. He said it's ok, so i ripped it out of the testing/simulating equipement and worked it with a hammer. Then i kicked it into the direction of the non-repairable box.
But that was quite a while ago, like the TRS80.
But that was quite a while ago, like the TRS80.
The click feel of the keys as they were depressed is called 'tactile feedback'.
Ah, memories... Well, except for us remaining CoCo hobbyists who still gather
each year with new products (LCD monitor adapters, Compact Flash drive
interfaces, etc.). Stop by!
http://members.aol.com/clubbbs/glenside/
each year with new products (LCD monitor adapters, Compact Flash drive
interfaces, etc.). Stop by!
http://members.aol.com/clubbbs/glenside/
Something from Ohio Scientific. I don't even care if you crack it open, but it would be nice to see one running. With a little B&W TV with an ATV Research transducer (or whatever you'd call it) to broadcast the video signal to the TV. Add a tape recorder and you're really cookin'!
You are right! Those were the good old days. I still have my Tandy Model 1 that did so much with 64 k memory. Haven't turned it on in years. It was great when it worked but the chip manufacturers didn't seem to care much about reliability in those days. Chip failures were so common I unsoldered all the chip and replaced them with sockets so I could more easily replace chips! And I loved the program loading system, a tape recorder. It was great to be able to load a program tape into the recorder, have a sitdown dinner and finish just a the tape was finished loading! The monitor was the first true digital, black or white. Stil have a pile of cassetes. I think I'll see if it still works.
Newspapers were just making the change from "hot lead" typesetting to computers when my employer handed me my first "Trash 80." In the mid-1980s I was a reporter for a Pittsburgh newspaper working out of bureau offices of a neighboring county when an editor called me to get on my horse and cover a major fire in a small town northwest of Pittsburgh. I already was using the TRS-80 to transmit stories by direct wire to the paper. But, I decided to take it with me to the fire. It turned out I made a good decision. Two firefighters died in the fire, so that placed my story on Page 1 -- with a serious deadline!
After getting my facts together, I snuggled into my car with my TRS-80 on my lap, and I knocked out the story in half an hour.
Now, how to send it?
I spied a pay telephone (Remember them?) at the corner. Grabbing my accoustic couplers and the TRS-80, I ran to the phone and called the computer in the main office.
"Be-e-e-e-e-e-p" said the main computer. I hurriedly connected the couplers, pressed a couple of function keys -- and crossed my fingers.
The story crossed in under a minute -- at a screaming 600 bytes a second.
I was agog! The thought of a front-page story jumping 60 miles with such speed left me breathless. I then realized that distance had been conquored, and the newspaper business would never be the same.
Today I am retired -- and surrounded by thousands of dollars worth of computers and periferals capable of creating entire newspapers and high-quality videos and other multi-media pieces.
And that TRaSh-80 on a sidewalk in a small Pennsylvania town started it all.
-- Gabe Ireton
After getting my facts together, I snuggled into my car with my TRS-80 on my lap, and I knocked out the story in half an hour.
Now, how to send it?
I spied a pay telephone (Remember them?) at the corner. Grabbing my accoustic couplers and the TRS-80, I ran to the phone and called the computer in the main office.
"Be-e-e-e-e-e-p" said the main computer. I hurriedly connected the couplers, pressed a couple of function keys -- and crossed my fingers.
The story crossed in under a minute -- at a screaming 600 bytes a second.
I was agog! The thought of a front-page story jumping 60 miles with such speed left me breathless. I then realized that distance had been conquored, and the newspaper business would never be the same.
Today I am retired -- and surrounded by thousands of dollars worth of computers and periferals capable of creating entire newspapers and high-quality videos and other multi-media pieces.
And that TRaSh-80 on a sidewalk in a small Pennsylvania town started it all.
-- Gabe Ireton
BTW, in case you were wondering, the empty socket was for the (optional) Extended Color BASIC ROM. I'm suprised anyone actually bought a CoCo2 without Extended Color Basic, as this was a requirement for most of the BASIC programs that were published in CoCo magazines at the time, and also required for the optional 5 1/4" disk drive. Very few CoCo 2's were manufactured without the Extended Color BASIC ROM.
Today's kids call it a hack. We had some of the first hacks. Remember you could take a blank eprom and build an eprom burner to fit into the expansion slot using instructions from MICRO 80 magazine. You could then burn a copy of your friend's extended color basic chip for about $12? I think the Extended Basic chip was close to $100 extra so alot of folks didn't purchase it. However, once you had it, there was no going back especially if you were serious about programming.
There was also a hack to piggy back more RAM chips to take the CoCo to 128K of memory! Massive Dude! Alot of all-nighters soldering but the projects never ended...the information flow on these little guys was amazing. I wish we had that kind of info on todays machines!
There was also a hack to piggy back more RAM chips to take the CoCo to 128K of memory! Massive Dude! Alot of all-nighters soldering but the projects never ended...the information flow on these little guys was amazing. I wish we had that kind of info on todays machines!
Having befriended an adult who worked at the R/S, I was able to "csavem" my extended basic right at the local store.. Gee, I hope the statute of limitations is up on that one now that I publicly admit it! 
Oh well, no matter - I now own a coco with a REAL ExtBas rom!
Now.. let's not admit anything about taping over cartridge pins to allow them to be inserted w/o the auto-detect...
Oh well, no matter - I now own a coco with a REAL ExtBas rom! Now.. let's not admit anything about taping over cartridge pins to allow them to be inserted w/o the auto-detect...
We larcenous little hackers figured if the store personnel weren't paying any attention to us then it was fair game to csave games after disabling autostart with a strip of paper. I was in awe of the programmer who wrote the Spectrum Analyzer "game". Way under one kilobyte, IIRC.
Some later games would write back to the ROM address space to spoil that scheme, so we built RAM packs with write disable switches.
Some later games would write back to the ROM address space to spoil that scheme, so we built RAM packs with write disable switches.
A few recommendations...although not all are technically pure "computers", they are all computing devices from the last few decades:
Heath Hero Jr robot
Milton Bradley's Big Trax programmable tank
Vectrex video game system
Nintendo's Virtual Boy game system
Original Apple Macintosh
RCA SelectaVision Video Disc Player [not a laser disc player]
Mego's 2-XL Robot [8-track based]
IBM's PC Jr
TMX Tickle Me Elmo
I could go on & on & on Hope that gives you some ideas. GL, and THANKS for the ones you've taken on thus far. You rock!!!
Dan
Heath Hero Jr robot
Milton Bradley's Big Trax programmable tank
Vectrex video game system
Nintendo's Virtual Boy game system
Original Apple Macintosh
RCA SelectaVision Video Disc Player [not a laser disc player]
Mego's 2-XL Robot [8-track based]
IBM's PC Jr
TMX Tickle Me Elmo
I could go on & on & on
Hope that gives you some ideas. GL, and THANKS for the ones you've taken on thus far. You rock!!!Dan
I seem to remember that Commodore made a portable version of their C-64 that was similar in style and structure to the old Kaypro luggables. However, I think the portable C-64 actually had a color screen.
I'd love to see one of those cracked open if you can get your hands on one.
I'd love to see one of those cracked open if you can get your hands on one.
Interesting to see the CoCo hit a mainstream outlet like TechRepublic... although the slideshow captions lack somewhat in a couple of places: Mylar ribbon on the keyboard was no "soldered" into place, it actually slips on and held by contact pressure onto the socket on the main board. Reseat the chips and plug the RCA connector on the back to a regular TV set, channel 3 or 4 and try it again... ol'CoCo might as well not be DOA
It appears to be a permanent connection to me, but that could be just a build up of gunk that is acting like a glue.
We did hook it up to a TV, but no signal. The previous owner said the box was dead and our cursory check confirmed it.
Now, if given the time and parts, we could probably revive it.
We did hook it up to a TV, but no signal. The previous owner said the box was dead and our cursory check confirmed it.
Now, if given the time and parts, we could probably revive it.
My dad still has a few of these in the attic.... One of my earliest memories was watching my parents play Ants on that thing.... Many an hour was wasted by me on that box and there were the piles of accessories my dad collected for it.
Sigh.... Good times.
Sigh.... Good times.
It would help if the person taking these apart had a clue as to what things were. The yellow color on the transformer is just transformer varnish, not anything to indicate DOA status. The perforated metal around the transformer is indeed a shield to keep the magnetic field from interfering with a standard CRT display. The "fused" dust and corrosion is an example of what happens when storing a piece of electronics in a damp and dusty area like a basement, attic, or shed. The chip functions aren't hard to explain. I have reference books on every one of them and probably have the parts themselves in bins.
is probably a Schmidt trigger. Input is an analogous signal and a threshold. Output is "1" if the signal is higher than the threshold, "0" if lower (there is actually a plus/minus epsilon if the signal is ascending or descending). All that, inverted. Probably used as a clock generator with a simple RC circuit.
I doubt it, as its a 40 pin IC. More likely its an interrupt controller for the CPU. I dont recognise the RAM part number. Are these static or DRAM?
The MC6883 chip listed on the photos essay as a "trigger inverter" is actually called the Synchronous Address Multiplexer, or SAM for short. This 40-pin integrates several functions like clock generation and synchronization for the 6809E MPU and 6847 Video Display Generator, the 40 pin by the RF modulator, up to 64K DRAM control and refresh duties and provides device selection based on MPU memory address to determine if the MPU access is to DRAM, ROM, PIAs, etc. Programmers learned to exploit the CoCo's potential by learning their way around the SAM. This chip would later be replaced by a LSI on the CoCo 3, the GIME chip. Got to love those acronyms
I recently came across my old Motorola tech docs on the old SAM chip... It was designed SPECIFICALLY for interfacing the 6809, 6847 roms, and DRAM. The CoCo was pretty much the design test circuit for the SAM chip according to those docs. It definitely was what made the Coco a "coco".. at least insides..
Not all of those ribbon cables plugged into a socket. Some had a pin connector permanently attached to the cable and were soldered to the board. From the pictures that is what this appears to be.
The CoCo3 eliminated the RF out for a composite out requiring a composite monitor.
Underneath was a connector for a proprietary RGB monitor hookup for the CM8 (square black)
Underneath was a connector for a proprietary RGB monitor hookup for the CM8 (square black)
I did not spot a mention in the article but this is actually a TRS-80 Color Computer II. The original CoCo had a "chicklet" keyboard and larger case.
I boosted my CoCo I to a whopping 64K by piggyback soldering memory chips and using a spare logic gate for bank switching. SUCH MEMORIES!
I boosted my CoCo I to a whopping 64K by piggyback soldering memory chips and using a spare logic gate for bank switching. SUCH MEMORIES!
The last CoCo I's built had the CoCo II style keyboard with a white case, but instead of having the cooling vents on top like the CoCo II, they had the cooling vents built into the corners of the top of the case like the silver CoCo I's.
I used to work at Radio Shack when the CoCo-3's were out, and they had those full-profile keyboards on them like in the photo.
I owned (and still own) a CoCo-II with the low-profile keyboard. White case, the ribbon of the keyboard was easily disconnected from the board. It plugged in similar to how an edge-card would on my model.
Upgrading it from 2116's to 4164's was easy. Pull out the 2116's from the sockets, put the new chips in, and solder a single jumper and that was that. (the jumper was for the voltage. 2116's used lower power than the 4164's)
I do remember shortly after, wondering what would happen if I swapped out one of the ram chips with the sam chip, just to see what would happen.
Nice show of sparks, and the smell was impressive. Took a little convincing with an electronics supply place that, no, I don't need to test the computer, yes, I'm sure that's the problem, yes, just sent me the chip.
They ended up sending me 2 for the price of the one replacement sam chip, without telling me they would. Wish I could remember their name, pretty stand-up company.
Anyways, I've kept my CoCo-II around with eventual plans to use it as a controller for a model railroad, controlling all of the lights and switches. Never did get around to it tho. Would be perfect to have hooked up to some basic stamp modules.
-- Smoovious
I owned (and still own) a CoCo-II with the low-profile keyboard. White case, the ribbon of the keyboard was easily disconnected from the board. It plugged in similar to how an edge-card would on my model.
Upgrading it from 2116's to 4164's was easy. Pull out the 2116's from the sockets, put the new chips in, and solder a single jumper and that was that. (the jumper was for the voltage. 2116's used lower power than the 4164's)
I do remember shortly after, wondering what would happen if I swapped out one of the ram chips with the sam chip, just to see what would happen.
Nice show of sparks, and the smell was impressive. Took a little convincing with an electronics supply place that, no, I don't need to test the computer, yes, I'm sure that's the problem, yes, just sent me the chip.
They ended up sending me 2 for the price of the one replacement sam chip, without telling me they would. Wish I could remember their name, pretty stand-up company.
Anyways, I've kept my CoCo-II around with eventual plans to use it as a controller for a model railroad, controlling all of the lights and switches. Never did get around to it tho. Would be perfect to have hooked up to some basic stamp modules.
-- Smoovious
I remember saving programs to the optional cassette recorder, then trying to reload them later using the "cloadm" command and going to make a sandwich during the ten minute wait.
I graduated from Southeast Missouri State University with a B.S. in Electronics in 1983. I had to "build" a project for one of my classes. I built a Timex Sinclair ZX80 from a kit I ordered from Radio and Electronics Magazine. What a blast from the past. It took me all of one evening to build. The ZX80 was housed in a little box about 8 inches square. It had a membrane keyboard and 8K RAM, upgradeable to 16K. That would be a cool dinosaur to feature. If you need one, let me know...I'll send you mine. I still have it, and it used to work when I boxed it up.
Please don't waste this cute little fella- I would love to add it to my outdated collection of electro gadgets-I am also an elementary school teacher, and like to show olkdies to the kids.
Marian
Marian
My old ZX80 is now in a museum!
If yours is still working, go onto ebay and check out what they sell for before you give it away - you may be pleasantly surprised, although for some reason they seem to go for more in the UK than the US, not sure about Australia
If yours is still working, go onto ebay and check out what they sell for before you give it away - you may be pleasantly surprised, although for some reason they seem to go for more in the UK than the US, not sure about Australia
I remember building one of those. I played a bowling game on it all night one night until 3 a.m. or something. It really couldn't do much more than that. But I thought it was just so cool.
Terri
Terri
I can still hear that sound like it was yesterday....
ErrrrEEE....ErrrEEEEEEEEEEE[click]EEEEEEEEE[Click]EEEEEEE [etc...]
ErrrrEEE....ErrrEEEEEEEEEEE[click]EEEEEEEEE[Click]EEEEEEE [etc...]
- despite its cumberome ways, the cassette interface in the CoCo was pretty reliable considering the alternatives. I toiled away just with cassette storage for a long time before making enough $$$ for my first disk drive. Had you been using a Commodore machine (VIC 20 or C64), then you would have had time to issue the LOAD command, go make the sandwich, brew some coffee, eat at a leisurely pace, wash the dishes and be back on time for the program to finish loading. Not putting down the Commodores here, I have a few and love them. It was just an era of fun compromises when choosing which PC to go for. 
Any body need schematics on the old Radio Shack equipment ?
I have the original books for Basic and Extended Basic that came with mine. In fact I still have it and the disk drive that goes with it. Also the printer interface. Was a great computer in it's day.
Isn't it funny - one more than that Motorola lost - first the televisions -then the memory chips (Intel and Apple).
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