0035 We have a broken TRS-80 Coco 1 in the basement! (And a repair on my other channel!)
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- Опубліковано 14 чер 2022
- On today's SMMC, a lovely viewer has sent in his old family's TRS-80 Color Computer 1, a Multi-PAK and a floppy disk drive. While I have a Coco 2 and 3, I have never had a Coco 1, a very popular computer in the US and Canada.
-- Video Links
Repair of this machine:
• This TRS-80 Color Comp...
Adrian's Digital Basement Merch store:
my-store-c82bd2-2.creator-spr...
Support the channel on Patreon:
/ adriansdigitalbasement
Adrian's Digital Basement (Main Channel)
/ @adriansdigitalbasement
-- Tools
Deoxit D5:
amzn.to/2VvOKy1
store.caig.com/s.nl/it.A/id.16...
O-Ring Pick Set: (I use these to lift chips off boards)
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Elenco Electronics LP-560 Logic Probe:
amzn.to/2VrT5lW
Hakko FR301 Desoldering Iron:
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Rigol DS1054Z Four Channel Oscilloscope:
www.rigolna.com/products/digi...
Head Worn Magnifying Goggles / Dual Lens Flip-In Head Magnifier:
amzn.to/3adRbuy
TL866II Plus Chip Tester and EPROM programmer: (The MiniPro)
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www.aliexpress.com/item/33000...
TS100 Soldering Iron:
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www.ebay.com/itm/TS100-65W-MI...
EEVBlog 121GW Multimeter:
www.eevblog.com/product/121gw/
DSLogic Basic Logic Analyzer:
amzn.to/2RDSDQw
www.ebay.com/itm/USB-Logic-DS...
Magnetic Screw Holder:
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www.harborfreight.com/4-inch-...
Universal ZIP sockets: (clones, used on my ZIF-64 test machine)
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RetroTink 2X Upconverter: (to hook up something like a C64 to HDMI)
www.retrotink.com/
Plato (Clone) Side Cutters: (order five)
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Heat Sinks:
www.aliexpress.com/item/32537...
Little squeezy bottles: (available elsewhere too)
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--- Links
My GitHub repository:
github.com/misterblack1?tab=r...
Commodore Computer Club / Vancouver, WA - Portland, OR - PDX Commodore Users Group
www.commodorecomputerclub.com/
--- Instructional videos
My video on damage-free chip removal:
• How to remove chips wi...
--- Music
Intro music and other tracks by:
Nathan Divino
@itsnathandivino - Наука та технологія
i love how the box it was shipped in had the basement box checked
I noticed that, too. Nice touch.
@Adrian - The floppy drive you are holding there was manufactured by a company called Remex. Most visibly, these drives were used in the DynaLogic Hyperion, and some variations of the Otorona Attache.
My father had come across a massive surplus cache of them that were selling for $49 in 1984, when a typical double sided Tandon TM-100-2 would cost $350. We soon found out why: The heads were unbelievably misaligned, and required us to go through with a head alignment disk and a scope, to fix them.
Adrian, thank you for the note at the end regarding the Telegram comments. I received one from an earlier video and decided to reach out. It was soon apparent something sketchy was going on and I put a stop to it. I hope no one else fell for it...
Yes, the return of the 40+ minute SMMC! My day (well, two consecutive days!) is made :D
"This isn't a drive repair video..."
/me puts popcorn away
At 23:00 Adrian commented on the wear marks at the bottom of the keyboard. Maybe this computer was used primarily for gaming? The wear marks on the keyboard appear to line up with the up/down (on the left side) and left right arrow keys (on the right side).
Also could be somebody who was heavier set and their arms were lifted by you know what. I picked up a trs-80 model III and had similar wear marks. Also know that weight gain is a common side effect from insulin/being diabetic, just maybe.
Man I just love seeing old computers like these that so obviously have been loved and have wonderfully complicated backstories. You can tell that whoever owned machines like these got their moneys worth and then some!
39:45 Deoxit and a glass fiber pen. If necessary, cover it in SMD flux and tin the contacts like giant pads.
And if you don't have a fiberglass pen like most people, use a pencil eraser.
I am looking forward to seeing more on this one.
Adrian -- JMR Electronics made enclosures about that time for many computers including PC's. I worked at Micropolis and we used to purchase his enclosures and we sold drives in the enclosures. I knew the president of the company and worked with many of their staff. Thanks for the great videos -- I really enjoy them.
"Deoxit that socket!" 😆
That was like watching a horror movie.
Dude, old tech was noisy, that was the beauty of the old peripherals.
After a while those horrible sounds, as one called it, was a symphony of success.
Thanks for posting.
Looking forward to the proper repair video!
Definitely looking forward to the repair video in the future!
Since I grew up with the Coco I'm really looking forward to the repair video!
Yes, the MPI (Multi-Pak Interface) allows you to use multiple cartridges at the same time, which is why it has all that extra support logic in it. The CoCo came with a variety of cartridges you could use with the system. At one time for my MPI, I had a Disto II disk drive controller, a Disto RS-232 Pak, and a Speech/Sound Cartridge plugged in at the same time.
Finally I see why it cost as much as the Coco itself. That is tremendously more complex than I imagined. As a kid in the '80s, I could not justify the cost to my parents who would have paid for it. My $5 weekly allowance was not going to cut it.
One of the many things I like about your channel is the variety of retro computers/components that you look at. Despite the prevalance of Radio Shack stores, I never saw someone with a CoCo in their home.
TRS-80s are famous for the silver plated edge connectors corroding quickly. That 3rd party gold plug-on adapter was an attempt to improve things from stock.
I did the composite mod as a teen. Got the board mail order from an ad in one of the CoCo magazines. Getting up the courage to break the warranty void seal was the hardest part of the job.
Haha breaking the seal. I went through that uneasy feeling as well when I broke through mine lol
@@sideburn the hardware modder’s cherry, lmao
@@kaitlyn__L 😂
It's an early CoCo 1, retrofit with the 'melted' keyboard from the early CoCo 2. Later CoCo 1 cases had the Radio Shack badge centered instead of off to the left, and lacked the RAM badge. The original CoCo 1 boards could only support 4 or 16K of RAM, but were upgradable to 64K with a hardware modification. I got my 4K CoCo in the summer of 1981, and upgraded it to 16K myself with 8 DRAM chips bought off the rack at Radio Shack. I took it to a local Shack (actually an independent dealer, as in the sticker on this computer) to have it upgraded to 64K, since at the time (I was in Junior High) I was a bit leery of attempting the mods myself. I'm glad now that I did, since they put the official 64K badge on it, which I now gather is a bit uncommon. They also added the Extended Color BASIC ROM at that time.
There were many articles about how to do the mod yourself, and the lack of a 64K badge suggests that this upgrade may have been a DIY job. Later CoCo 1 systems were sold as 32K machines, but most if not all of them used 64K chips, some of which may have been 'half-bad', ie, had bit errors in the upper bank. Even with a full 64K of RAM, the CoCo 1/2 usually only has the lower 32K active. However, it is possible to copy the contents of the ROMs into RAM and put the machine in all-RAM mode. The OS-9 operating system requires 64K and only uses the disk 1.1 ROM to boot.
Another commenter noted that the early Multi-Pak Interface (MPI) didn't support software switching. I don't recall ever hearing that before, though my MPI was a later one, matching the CoCo 2/3 case. (Indeed, the manual is archived online, and software selection has always been a feature.) However, the early MPI had a problem with address decoding in the PAL chips on it that made it subtly incompatible with the CoCo 3. A revised PAL fixed that problem. There was also a problem with MPIs reliably getting IRQs to the CoCo, but that was only an issue when running OS-9 LII on the CoCo 3.
The MPI could, of course, be used to switch between game cartridges, but it was most useful for using multiple hardware controllers. Usually you would plug the disk controller into slot 4, and maybe an RS-232 Pak in slot 3 and an Orchestra-90 or Speech & Sound Pak in slot 2. It was also used for the high res joystick/mouse adapter used by the CoCoMax paint program (largely as a copy protection scheme) so you could use it and the disk drive at the same time. There were quite a few 3rd party hardware expansions that plugged into a CoCo cartridge slot back in the CoCo's heyday, including real-time clocks, speech synthesizers, hard drive controllers, MIDI controllers, and voice recognition systems.
Another use for the MPI is that it includes 12V on the expansion bus. The CoCo 1 did as well, but it was removed in the CoCo 2 and 3. The earliest floppy disk controller for the CoCo required this 12V power supply, and so won't work with a later CoCo unless you plug it into an MPI. Interestingly, it is only this early FDC that can easily be modified to work with high-density disk drives, since it has a separate data separator IC.
Finally, the MPI was very useful for dumping the contents of ROM Paks onto floppy disk. Then you could play Downland or Dungeons of Daggorath _without_ the cartridge or the MPI if you frequently used disk-based software, which became increasingly common.
Looking forward to the full repair on the CoCo.
You comment is interesting. I had a good bit of coco stuff, starting with the 2 with chiclet style keys and the 3. I thought I remembered the 232 pak had to be in 1 and the disk controller in 4, which really annoyed me because of the height of the 232 pak.
It's funny people mention the expansion connector and lockups. I had a MPI when I had my COCO 2, and the thing was always locking up. I was back to Radio Shack for repair many times.(I was young and had no tools or knowledge on how to fix it at the time) I replaced it with a COCO3 and never had the problem again, nor any problems with OS-9 L2 beside the agonizing pain of using that with a single floppy drive!!! (Try to make a copy-it's painful-at least 30 swaps!!) I'm now wondering if there was never anything wrong with the coco besides the connectors. But at the time I didnt care-the COCO 3 was out and I had to have that anyway and it was a good excuse!
Love this computer - I will dig it back out one day soon have have a play with it.
@@jimb032 There's a thriving community on FB, and a lot of modern upgrades. OS-9 development has continued, and the modern version is NitrOS-9, which has better performance than the original, and much improved performance if you swap a Hitachi 6309 in for the 6809. The CoCoSDC is a currently produced SD card interface that emulates the original FDC at the register level, and also provides hard disk sized disk images. Also, there's Drivewire, which serves disk images up over the bitbanger port from a modern PC or Raspberry Pi, as well as networking, printing, and RTC in (Nitr)OS-9. There's a new NitrOS-9 distro in Beta called EOU (Ease Of Use). With a CoCoSDC and/or a Drivewire cable, NitrOS-9 is a joy to use.
I can certainly imagine what a pain it would be to try running OS-9 off a single floppy.
@@joelavcoco thanks. I still want a second drive for my fd-501. I already purchased me a cocosdc, 3d printed a case and a look alike label for it in anticipation of getting out my coco. I'm in a bit of an apple ii kick right now but I'll get back around to the coco. I looked into drivewire, I understand you can use that with the apple and the coco in so that is interesting.
By chance do you know the number for the floppy drive itself in the fd-501?
@@jimb032 Not off the top of my head. My original floppy drive system was an earlier version, and the controller was not labeled FD-501. But any floppy drive with a standard 'Shugart' interface should work, including 3.5" drives. Even the 1.44M drives work fine, _if_ they're used with low density (720K) disks. Disk BASIC only supports a single-sided, 35 track format, but you can use up to double-sided, 80 track formats in OS-9.
The main 'gotcha' is that the CoCo uses the originally intended Drive Select signaling with a flat cable, and not that twisted cable nonsense. So any drive that is to be addressed as Drive 0 must have a switch or jumper for D0. Later cheap drives made for the PC market were hard-wired for D1. These can be used as D1 on a CoCo system, and some of them may be able to be rewired to act as D0, D2, or D3.
I'm a long time retro computer fan, my first computer being my Acorn Atom which I built in it's kit form. But have only recently found your channel Adrian. I have however watched many of your videos over the last two weeks and found them to be excellent. I love your style of presentation and your clear explanations. Thank you so much for the excellent videos.
Oh wow, I played around with one my school had back in the 80's. Looked/felt like super high tech compared to other computers we had.
That keyboard isn't aftermarket, it's an official upgrade from Radio Shack. I think it shipped on some "CoCo 1.5" computers (same size as the CoCo 1 but had a white case). I think also that the CoCo 1 was originally only upgrade-able to 32K, and so some of those bodge wires were used to get it up to 64K (Which the CoCo 1.5/2 supported natively).
The Composite output is not something official, though.
Also that multi-pack interface is the 1st generation type, and unfortunately that means that it doesn't have a "software select" mode on later gen multi-pack interfaces, which could be used to support the floppy drive in slot 1 and other packs in slots 2-4 at the same time.
Ah too bad about the Multi-Pak -- could those extra wires inside the coco (that go no where) be there to support this in a hack way? I guess I didn't see anything in the Multi-Pak where those could have been soldered onto.
Cool setup, can't wait to see you get it working.
Definitely a lot to work on. Looking forward to your next video. Thanks for sharing
I honestly cant wait for the repair video !
Nice! Coco I was my first computer so it has a special place in my heart. :-) Like others said, that looks like a 64K bodge near the RAM. I also did that keyboard upgrade. You could get it done at RS, but there were some dealers that sold the upgrade kit and that's what I did - came with the keyboard, the adapter from flex cable to pin connector, and a 6822 to replace one of the 6821s. I don't know why that was required tho. I also don't remember having a bodge from the cable adapter to that test point. I still have mine, and a couple of Coco 2s that dad bought to use at school. He and mom were teachers and at that point the only computers in the schools were in labs. Dad's also has a composite mod, but for some reason it's only monochrome out.
BTW, if you ever get a Coco 3 be aware that the early Multi-paks require an upgraded PAL chip. In fact I think it can damage the Coco 3 if you don't have the upgrade. There's at least one guy I've seen on the net selling some Coco upgrades including that chip. I think mine has a damaged PAL anyway and since the upgrade IS backward compatible I've been meaning to pick up one myself.
Looking forward to seeing the fixes!
Oh, and you can use multiple carts at once tho only one ROM cart at a time. The switch only switches a select line as I recall. But if you have carts that don't have ROMs you can have multiples active at once provided they don't occupy the same address space (memory mapped I/O, so you loose memory to devices). I routinely used my floppy drive (with the ROM selected) with the X-Pad and Real Talker voice synth simultaneously since those had no ROM.
Memories... i had one from my older brother in 1982-83, after my Timex Sinclair 1000!!! I've made a lot of things with this chicklet coco! Good old time!
Pretty sure that this one has been retrofitted with the CoCo2 keyboard, every silver CoCo 1 that I've seen had the "Chicklet" keyboard. RadioShack actually sold the CoCo2 keyboard by itself as a hobbyist part, I remember seeing one on the pegboard shelf at the local RadioShack back in the day 😂 There were also late production CoCo 1's that had the CoCo2 keyboard, and the CoCo1 case finished in white/beige instead of silver.
yes the keyboard has been retrofitted from the chicklet keyboard
I even remember seeing that keyboard on a shelf in Tandy in the UK.
ya i was gonna say every picture i have seen the coco 1 came with the chicklet keyboard.
@@rottmanthan it definately did and yeah its a coco 2 keyboard mod... they sold the keyboards seperately at one time and this was a really common mod... along with a power LED and front reset...
@@melanierhianna yes Tandy used to sell these seperately for use...
The first computer I had(well it was the family computer at first) was a breadbox 64. The first computer I remember seeing in school(in '85, I was in the 5th grade) was one of these with the earlier keyboard(keys were flat). It was hooked to an old green monitor and we only had cartridges, but we used it all the time in class.
My first computer. Ended up tearing it apart and hanging the PCB on the wall connected to my stereo with the the Audio spectrum analyzer cart. It became a dedicated spectrum analyziner 😂 and I became an Atari fan boy after that 😆
Great video! Love to see the earlier models with the K RAM Badge and the logo emblem on the left.
This is awesome. My first computer was a CoCo1... circa 1982 or so. I think the keyboard is probably a mod, in addition to the extra RAM and the video mod. Mine came with a chiclet keyboard.
Many a long year ago, I wrote an interesting program for that computer. It was designed to print text on the high-resolution graphics screen. This was never supported by the hardware. If you had a BASIC program and you wanted text on the graphics screen, you had to use BASIC's drawing commands to draw the letters.
I managed to shoe-horn a machine code program into a tiny amount of memory. The character-set table which the program used was longer than the program, by quite a lot. 😄 (2048 bytes RAM for the table, but around a quarter of that for the program).
The program was written in assembly code and used the Program Counter Relative instructions so that it could be loaded anywhere in RAM. Usually, I'd clear 6 pages of graphics memory and then use the first four for the high-res graphics screen (it required 4 pages for the full screen) while loading the program into the two "spare" graphics pages.
The program had a table with the full 8-bit IBM extended ASCII character set. It allowed you to fully control the cursor, screen clearing, and do advanced stuff such as redefining characters from within the BASIC program, put a cursor on the screen, reverse the video (black on white instead of the default white on black) and more. You got 24 lines by 32 characters per line.
The program was accessed with the USR (user) command in BASIC. If you gave the command a number, the lower 8 bits of the number would be used as an index into the character set so you could access all 256 characters that way. If you instead sent a string into the command, it would print whatever was in the string... but it would also interpret control codes as cursor and screen controls and as character redefinition commands. There were escape commands which would access the printable characters stored in the control character locations (0x00-0x1F) so you could still print the entire character set using a string.
I gave up working on the program because the COCO was falling out of favour as the IBM compatible computers took over the market, but figuring out how to make the computer "dance to my music" was fun.
Ex-Cell-O is a company best known for its cold forming machines, and which once made precision grinder spindles.
I think the wear marks are from where your hands would be to use the cursor keys. Possibly for games.
pencil eraser on the gold plated contacts , but something tells me there is VERY little gold plating on there , as gold does not corrode like that
A lot of contact edges are brass rather than gold, so that tracks. Brass looks a lot like gold without real gold nearby to compare against. A lot of “gold plated” audio jacks are actually brass too. Which isn’t really bad at all, brass is an excellent conductor. It’s just not corrosion proof!
Check out those ceramic RAM chips! And love the composite mod. I bet the gator clip was used so consumers could fit it without soldering
I've been to that Radio Shack in Los Alamos in 82-83, and over the years. Used to live in Santa Fe, but had friends and family there. I think the last time I went there was around 2007. 😭
Played around with a Coco 3 once. The RF signal was so strong I was able to NOT hook my TV up and it had perfect reception.
That was really interesting to listen to and watch, particularly as I used to own a CoCo variant: a Dragon 32 🙂
Definitely an aftermarket keyboard - original keyboards on the COCO 1 were the chicklet square keys, one of my HS friends had that model and he typed a lot of programs in somehow - one of the smartest kids I ever knew, was doing assembly programming in grade 9.
I started with a 16k extended color basic coco 2 t hat we upgraded to 64k - that little machine is pretty much responsible for my career in IT.
Radio Shack had licensee stores, some of which were completely branded as Radio Shack. If a particular store survived the second bankruptcy, then it was usually or always a licensee instead of a corporate store.
Inspired by your channel/videos, I dug out the CoCo 2 I got from the flea-market, as I didn't recall which version/model (1, 2, 3) I had. Unfortunately, something was rattling around inside! A quick disassembly in the kitchen later and I found the culprit, a teeny-tiny spring! Pretty sure it wasn't part of the CoCo and just fell in through the vents, but it's very good I checked! Wouldn't want it shorting anything out.
Being as it's late at night and I'm not sure where my RF adapter is, I decided not to plug it into the entertainment center for a test. I have a single cartridge for it, one that was in my Commodore collection as an unknown/unlabeled cart that didn't fit any of my Commodores or anything else I had available.
Turned out that the blank black cartridge was Project Nebula, and it worked! It's crudely labeled now.
39:26 Man, one of those slots is looking pretty green!
Has there been a video on the multi-pak yet? I've seen the CoCo-1 repair video.
Cool, a rare third party disk drive for the CoCo! The official RadioShack part for the CoCo1 is the same as a TRS-80 Model I drive, single sided. The CoCo2 ones were the same, just in an ivory case 😂
The TRS-80 Color Computer 1 was our family’s first computer, and along with it came a Sinclair ZX 80 and a Timex Sinclair 1000. In hindsight, I think the Sinclair worked fine, but I could never figure out how to use them beyond turning them on. The TRS-80 CoCo 1 (we just called it the “Trash-80”) was great. We did some elementary BASIC programming on it, but even though we had the cable to connect a tape recorder, I could never figure out the commands to make that work, so it regressed (to us) to be a computer that we couldn’t save or load anything on. Recently, I bought a wonderful condition one to use in current day, and this time, I intend to get to use tapes! The first one had a chiclet keyboard, and I made sure the recent one did too.
I worked in corporately owned Radio Shack in the early nineties, there was a DBA Radio Shack a few towns over. It was owned by a local man and he did electronics repairs and sold Radio Shack merchandise. I think that the privately owned store dated back to the 60s.
You mentioned a dealer store. Well, I lived in a town in which the store was a hardware store with a section that served as the Radio Shack store. I imagine that these dealer stores were owned by mom & pop owners that served small towns in which were not located near a big city with a dedicated corporate store like many people would find in the later years of Radio Shack.
There was a similar one in a town I frequently passed through in my younger years, so your guess may be correct.
Me too! Part of a TruValue hardware store.
After you opened the case I kind of expected to see a little garage mouse looking back up at you :)
I had an original CoCo (with an E board) way back. There was a lot of discussion back then about repainting the case to repair those worn spots along the front edge. It was eventually found that a specific car touch-up paint was a perfect match: Mercedes Silver. I've no idea if that same shade is available today. (For anyone who read '80 Micro' magazine in that era, you would remember that the regular 'Gamers Cafe' column introduced a character called Mercedes Silver.)
Yep, I remember that as well.
Great video. Maybe try a brush on gold plating solution? You don't need to soak it and it should adhere to copper fairly easily.
I see that you finally turned the Eyoyo upside down! I did that as soon as I got it. It makes it much easier to access the inputs.
Oh man, I wish I knew you needed one. I ended up getting one that I thought was PAL but it is in fact NTSC but someone installed a 240v transformer for some reason I cannot fathom.
Could have been used in South America. Some countries down there run NTSC and 220V/60Hz. I know Peru does, and I think others do too.
0:25 - Not a Walmart pillow. You got upgraded to the premium Target house brand pillow packaging. LOL
Downland is my favorite coco game. Also the basic in the coco was very good compared to other basics of the time.
Bought at a 22-A store... and serviced at a 40- center (of which I used to work at one) :D
Doing all of the home modifications was very common on the Colour Computer, especially the CoCo1. That is the melty keyboard which came on the later run of the CoCo1 and early run of the CoCo2. I would guess the mod at the keyboard ribbon might be the lower case mod.
Yes, that is a seal from a medicine vial, such as for insulin.
As a kid, I had a coco 1 (16k later upgraded to 64k) that I paid radio shack to upgrade the keyboard from the original ‘chiclet’ keyboard to that one.. it was an official RS upgrade you could get.
As for the multipack, software could control the address decoding independently for the ROM space ($c000-$feff) and the part of the memory mapped I/o space typically used by disk controllers ($ff40-$ff5f) by storing the appropriate low and high nibbles at $ff7f…. Once software hit that address, the front switch gets deactivated until a reset.
Someone will correct me if I’m wrong, but I also feel like it actually let multiple carts share part of the rest of the I/O space at the same time - $ff60-$ff7e maybe??
Early version of the multipack don’t work with the coco 3 without modifications because the control register would ‘ghost’ from $ff7f to $ff9f clobbering new I/O registers (in the GIME Chip) in the coco 3
I had a CoCo 1 initially then a CoCo 3 back in the day. My CoCo 1 had 64K, switchable IRQ. Needed the IRQ mod for modems as Tandy/Radio Shack messed up in the PAL mod. Power led. My CoCo 3 MPI was switchable so older hardware would work as some addresses were blocked. My CoCo had power leds at the front. I wired them to the 5V and 12V lines as a diagnostic aid. I had an HJL aftermarket keyboard in my CoCo 1 and transferred it to the CoCo 3. Looks like it’s not executing code, thought the 6883 was bad but they do run warm. Wonder if it’s a PIA (6821/6822)? I did have a 6883 fail with flashing bars but your display looks like it’s not doing anything or it’s running but not able to execute ROM code.
"PLACE IN BASEMENT" on the top of the box, that is very funny :))
Hey Adrian, use a pencil eraser on the corroded edge connector contacts. It's very effective, and it doesn't trash the connector like a dremel would.
First time I see the insides of this computer.
I think U11 to the left of the RAM bank is an LS138 3-8 decoder he had to mod for the ram upgrade.
Those resistors look like 4k7 pull-up resistors.
The only reason he would've upgraded that computer, would be to play games.
Sexy case, cant wait to see it running, never seen this machine before.
The multipak is manual and Electronic device to swich 1,2,3,4 with pokes, Keyboard is coco 2, first series, The wear on the case is due to the chiclet keyboard that was wider and better aligns with the markings.
It is easy to tap a composite signal directly from the input to the modulator. Not great, but good enough for troubleshooting. It can be improved with the simple mods usually done on Sinclair Spectrums or Atari (using a 100uF capacitor or a transistor). You were lucky to get that a fancier mod that is getting the signal from the MC1372.
No one ever really used the 1,2,3,4 switch on the MPI as the slots were software selectable. So, for example, you could have a disk based terminal emulator load from disk, and internally the software could select back and forth between the disk controller cartridge and the RS-232 cartridge for network access along with disk access. So it was basically 4 expansion slots of which only one could be active at any moment, but could easily switch if needed.
The old TRS-80 edge card connectors for the expansions were just tinned copper. And they would oxidize quite badly. So many kits were sold that had a gold plated connector that you could solder right onto the existing edge card connector. I have several old TRS-80's in my possession that have had this modification done.
I personally never had an issue back in the 80's, but then again, i never used the "eraser trick." The eraser trick was to use a pencil eraser to "clean" the connector. This was bad because not only was it too abrasive, the rubber eraser contained sulfur, which causes more corrosion to happen.
Your best bet was an actual contact cleaner or just re-seat the connector several times to allow the contact fingers to wipe the oxide away.
Yay!
This was my first computer in 1981 with the chicklet keyboard (absolute garbage keyboard, and I tried learning touch typing on it... ugh). For as terrible as it was, I still loved it. That machine was magic to a 10 year old. Those wear marks look like they came from using the arrow keys; I used to rest my hands in exactly those spots playing games.
Radio Shack also had owner owned stores, franchise stores, particularly in small towns.
There's still a franchise store in a neighboring town here. Those are the last ones remaining.
Downland is wicked hard game. So many hours attempting to complete it.
A smaller town that I lived in in the early 2000's didn't have an official Radio Shack per se, it was an audio store which was a licensed Radio Shack reseller as well. I imagine Radio Shack had these types of franchises back in the 1980's as well.
Yep I remember a few drugstores that essentially had a mini Radio Shack in them as I called it
@16:29 If nobody mentioned it yet, that SAM chip typically gets very hot, as I recall. It even happened on the CoCo 2. I think with the CoCo 3 it was integrated into the GIME chip which ran much cooler--as I recall.
The orange & green garbled screen can happen when the computer isn't reading the ROM chip, but can be caused by other things too of course. I had something similar on a Dragon 32 I bought last year which I solved by reseating the ROM chip, cleaning both the chip & socket in the process, as well as using the equivalent of deoxit on the power switch and switching on/off several times. Not sure which of those tasks cured it, but it took a few presses of the on/off switch for the garbled screen to finally disappear and BASIC to boot. It's been fine ever since though.
👍 This.👆
Remex was a big manufacturer of paper and mylar punch tape readers and printing (punching) machines used on computers and industrial machinery from the 1960's to the early 70's.
I would say to desolder and remove that edge connector on the multi pack interface. Maybe you can find a more modern replacement to solder back on to the original pads?
The video interface probably has color composite, monochrome composite, and sound. I had a similar interface in mine.
That pattern on the screen looks like what is left by the memory test.
Either the memory test failed, or initialization of one of the PIA chips? PIAs can fail if you plug a joystick in with the power on.
That is probably an early CoCo 2 keyboard, but I've been told there were a few white CoCo 1s with that keyboard.
I'm gonna say those wear marks are due to gaming because that's where the arrow keys are.
The Room Essentials brand comes from Target, not Wal-Mart. Those pillows cost a bit more than $2 but they're still cheaper (and more reusable) than most packing material.
Packing tape residue can be removed with Bestine rubber cement thinner and an artist's spatula. Generic Bestine is sold as simply heptane. Bestine sells an oilcan-like applicator that you kind of need in order to use the stuff. Also good for price labels and other stickers as well. Probably not good to get on your bare skin though, it evaporates pretty quickly and probably not as bad to be around as acetone. - long time watcher/first time commenter. P.S. - I'd test it on the plastic first but in my experience the stuff is not very reactive unless you take a match to it.
Most of those bodges would be for the factory 64k upgrade. That old of a board didn't support 64k directly- wonder if it's got rev F or ET on it. The long red wire to the keyboard interposer is to connect the CoCo 2 keyboard to that older CoCo 1 motherboard, it provides pullup via the resistor pack on the interposer board. The 6822 was also used for the CoCo 2 keyboard as it was a better match to the impedance of that keyboard. Normally the first CoCo 1 keyboard used a 6821. Under the cardboard is just an AC transformer. The 6883's tended to run hot. You can use multiple carts at the same time in the multi-pak as long as they decode to different address ranges (disk drive and RS232 for example) but the slot is software-selectable so it's possible to use multiple same-type carts (multiple disk controllers, for instance, under OS/9)
18:24 New catchphrase? "DeoxIT that Socket!"
Looking at that wear pattern, the user might have had a hand condition that prevented using some fingers. I have Dupuytren's in my hands that makes my pinkie fingers useless so my hands are at the same position as the wear marks. Just a theory. It's great seeing a CoCo again, I had one in my teen years and haven't seen one since.
22:56 I'm guessing the wear mark there on the left was due to them using the up/down arrow keys possibly in games? The left/right ones are on the far right of the keyboard as well.
Yeah that's gotta be it!
You can use an electric tooth brush on the gold contacts, with some IPA or something like that. It'll have a very fine abrasive action. Just don't use an old one if you don't want the thing to smell like bad mouth smell... use a new one. They don't cost so much.
Adrian! I that keyboard is the one that belongs in the Coco2, which is my first computer and I still have it. Incidentally, my keyboard broke and it was replaced by Radio Shack with the later tall key design. If you want a OG keyboard for that, I'd love to have yours to make mine original and I'd buy you an OG keyboard and swap it if you are interested.
I have a nice Coco Collection, as it was my first and only computer in the house until I replaced it with a 1000HX. My Coco collection consists of. Coco2 64k, 3-512k, Coco2 type Multi-Pak Interface, FD-501 single drive, 2x deluxe joystick, Electronic Book, Kaola Pad, CCR 82 cassette, RS-232 pack, Orchestra 90, modem pak(cant remember model), DCM3 modem, OG Dust covers for disk drive and computer, DMP-130 printer, Audio Spectrum Analyzer, and a good mix of Cassette, Disk, and ROM pack games. I'm probably forgetting a good bit too. I even have the official RS store demo on disk for the coco at Christmas and some others. When I start to dig this all back out again (right now, I'm on a bit of an apple ii kick), I'll upload the demo to archive.org if it does not exist.
I really want a 2nd drive for my FD-501. If anyone knows the mechanism number, can you please share it? I'd have to dig mine out, but I'd like to start the search. If you know of one for sale, please let me know. IT looks like a Tandon TM-65 sans obnoxious door lever. I really want it to be period correct and match.
Edit-about dealer stores - that is all that is left in 2022, and I'm lucky to still have one near my parents house in PA.
The dealer network still exists. There is one dealer about forty miles from where I live.
Looking at the paint wear and the location of the cursor keys, I'd guess someone played a lot of games on the thing which used those keys specifically, so having to place the wrists in those positions, versus where they normally would be for regular typing... :)
Pausing at 8:40. I think the keyboard may be an aftermarket or retrofit of a later CoCo board. I never owned one of these computers myself, but a childhood friend had one, and his was definitely a chicklet style. First impressions with all those bodge wires and it's obvious someone had some fun in there - and a keyboard swap was likely one of those mods!
Edit: Catching up at 22:15 & now I know.
It's been ages since I had a Coco but most of the bodge wire stuff I remember from 35 years ago was due to the multipak being jostled and since it was unbuffered, the 6809 would pop super easily. When I unsoldered and replaced it with a
socket, I broke a few traces and had to bodge them.
It's possible that is what happened to your Coco 1
Also for the multipak, you could have the sound and speech cart and the disc controller plugged in at the same time so disk games could access it. I think I had a ""high speed" serial card as well (16450 maybe?) and a special DMA ram enabled floppy controller so that you could use OS/9 and not have the whole system freeze on disk access.
If I remember correctly the graphic chip does not require a working cpu to display data. The GPU just scans a section of ram and sets the pixel color to the value in ram. What you are seeing on the display is essentially the power up random values of the ram. This is set up using a dual port scheme so the gpu and cpu can access the same ram at the same time. (different clock phase though). I would say the cpu is not running or does not have access to the monitor rom. If it has been modified the address bank select could be messed up to use a custom boot/monitor rom in a cartridge instead of the onboard oem one.
Just use the contact cleaner to remove the sticky goo from the decomposing feet and the packing tape, works better than WD-40 and doesn't leave a smell or residue.
That's a CoCo II keyboard. The final keyboard for CoCo III had clustered arrow keys and some function keys. I don't remember the SAM chip running that hot. I'd check the CPU. That's a "Remex" drive. I had some of them but don't think it was that model. I think those mods around the 6820 are related to the 64k RAM upgrade. 32k was the max supported but with bank switching you could get to the rest.
Yep. It's actually the melted keyboard which was in the long white case Color Computer (in US) which was also sold in Europe as the Colour Computer II for a bit. Shortly after they've made the short white case with an even better keyboard which became the CoCo II on both sides of the Atlantic. This case was also used for the CoCo 3.
@@HomeComputerMuseum The chicklet keyboard lived on on the short case COCO2-I owned it. I remember it well, because the keyboard broke and RS replaced it with the tall key model, and for some reason, I remember not liking it as well.
could also be a 32k upgrade because sometimes RS bought 64k chips with 1 bad bank and used them for 32k upgrades. need to run some ram tests to see which it is
I'm not sure if anyone else has pointed this out yet, but I can explain the wear marks being off to the side. That's where the arrow keys are! If you were playing a lot of games on the system but didn't have a joystick, then your hands would probably be resting in just those spots to use the arrow keys.
I got a batch of Hyperion drives that look just like that one. Half of them had the power connector replaced with a short pig tail. I think they were problematic.
Try Tarn-X cleans corrosion no metal removal. Great on corroded ICs rinse ICs with water and air dry
My first computer was the 64k version. I wrote a payroll program using the cassette deck for storage. When I changed jobs I ran the spreadsheet cartridge and ran a small college's budget. It definitely would have had the chicklet keyboard. While it was insanely slow running the budget showing the school president how much faster this was than hand calculating changes that summer the school bought its firs XT, and a very early KMS Laser printer called the KISS and yes it stood for keep it simple stupid.
It would seem you can use multiple cartridges the switch seems only to select which is set to be read on boot.