Dragon32 Trash to Treasure | When Wales made a Micro Computer (pt1)

our MC is supported by monster joysticks calm level up your retro gaming with their joysticks feature in genuine San where arcade parts and one click print calm for your photos on canvas acrylic gifts and more local craftsman and global delivery [Music] [Music] [Music] hello cave-dwellers welcome to the cave for another trash to treasure so that part of the channel where we take a broken retro computer fix it up and try to learn the story of it along the way and you may be thinking what was that music in the intro that rousing all male choir singing at the top of their lungs well that was the Welsh national anthem others of you would probably stood hand on heart singing along to it because Wales is a proud nation a nation of around three million people on the west of Great Britain and they're known for many things they're known for mining they're known for Dylan Thomas for Lawrence of Arabia then infrared B of course but notably absent from that list is micro computers and it shouldn't be because this the dragon 32 is so named after the mythical creature that adorns the Welsh flag the dragon with the 32 a reference to the amount of memory it has these were the product of Dragon Data limited based in Port Talbot in Wales and all they really wanted to do was just to grab hold of their share of the fledging and computer industry here in the UK in industry the likes of Sir Clive Sinclair and other homegrown computer talents were enjoying great success in having decided they wanted to enter the market they needed to come up with a machine quickly and when we look inside we'll see some of the design decisions they made to enable that rapid development on release in 1982 though it did sell well and it attracted independent developers such as micro deal here and it spawned its own publication dragon user magazine this particular example was donated by Matt Bowden to the cave so Matt thank you so much for sending it in he says it's not working but you can see cosmetically it looks great and it also comes with the books the Polly's inside and even the power transformer which is a really nice addition so thank you Matt this is the first opportunity I've had to work on a dragon 32 so I'm really looking forward to it let's take it over to the lab and we'll see what we're up against [Music] the first thing that you'll notice then is its size this is designed to be more like a BBC micro anisette X spectrum it's got a lovely 53 key mechanical keyboard unlike that low-cost spectrum keyboard and a large roomy case it would have set you back a hundred and seventy-five pounds and it didn't come with a monitor for the display you'd either need to use the RF output here oh just around the back is a composite monitor port which is great that makes using these machines in modern times a much nicer and easier to use experience without the need for modification generously we also have two joystick ports present which are either side of a tape deck port you can use all manner of joysticks in those ports but popular at the time were these small analog style sticks and being called the dragon it opened itself up to all kinds of puns and wordplay when it came to advertising and this joystick advert is the perfect example some Georgian now has two choices red or green will slay the dragon and down on the bottom here we've got dragon dealers come out of your Kevin's there's also a reset button and a peripheral interface board if tapes were too slow then an official described was released in 1983 the third-party drives also existed this example here from Camilla includes a delta ROM based cartridge adapter so you would plug a cartridge adapter into the cartridge slot and then you're away with your disc drive and my cartridge slot sits here on the opposite side to the ports we've just seen and then if we look at the rear of the machine there is that power button the composite monitor out and a nine pin port which is not a serial port that's the power port careful then not to plug the transformer into the wrong thing if you have other devices nearby it could be easily confused a sticker on the underside shows us that this dragon has a serial number in the 90,000 range and I'll explain the relevance of that once we get inside cosmetically it needs a good cleanup and we could treat it to a new sticker that's got all creased up on the top here but there aren't any cracks or major cosmetic repairs and he did at all before we contemplate looking inside and indeed testing it we should turn our attention to the transformer if we're going to plug this in we want to make sure that it isn't going to damage your dragon so we'll quickly test it with the multimeter being a transformer it's job is to simply take the voltage down to twenty eight and eight and a half volts as indicated on the label here the DC conversion is performed inside the dragon our meter shows it's a little over but it's not under any kind of load at the moment so I think that's looking good if you're doing this yourself I'll include links in the video description to the resources I've used and also the pin outs okay now I'm satisfied that our transformer is good let's look inside and perform some more checks before we think about plugging it in [Music] our system is made up of two boards then on the top board the power enters the dragon here where it makes its way to a couple of voltage regulators via some capacitors for smoothing the system board expects 12 5 and negative 5 volts and those are provided by a 78 12 and a 70 905 voltage regulator the O 5 providing us with our negative 5 volt line this is then sent to the main board via this cable which in return receives the video and sound signals back and they can be enjoyed via the RF modulator or the composite out whichever is your preference I'm going to unplug this board from the main system board so that we can check the voltages that are coming through the cable before they enter the board and that's the safety precaution I recommend following on any retro systems before powering them on for the first time because it's so easy to fry those sensitive components let's turn our attention to the system board now and see what the dragon 32 is made up of for some of you things might start to look a bit familiar you see the dragon 32 was built around the Motorola datasheet design for the MC 68 83 Sam chip that handles memory management and peripheral control the purpose of using this was to create a new system as quickly as possible and another system built around the same design was the trs-80 color computer later known as the Tandy color computer or Co Co as a result they're very similar systems to the point where a large amount of the same compiled software will run on both machines the CPU is an MC 6809 II running at naught point eight nine megahertz it's a fairly sophisticated 8-bit CPU with limited 16-bit capabilities in terms of raw power this is ahead of the 6502 used in the commodore 64 and the z80 used in the british rival the ZX Spectrum which seems like a really good style for the system when it comes to memory that dragon was intended to originally house 16 K of RAM Tony Clarke and Richard Woodman who established the specifications then increased this to 32 K for launch just to keep up with the competition as a result this later board has 32 K onboard but let me show you this serial number board I happen to have next to me as you can see a daughter board has been fitted to the original design to give us 32 K where previously 16 would have sat this was that last-minute change to bring the spec up and get the dragon into the shops he would then be refined in later revision boards such as the one were working on today so our dragon had a capable CPU and memory close to other home systems at the time but what about its video capabilities visually the dragon 32 was quite garish black text on a green background was quite muddy and looked more like dark green text on a green background it's not pretty this is driven by a Motorola MC 68 47 video display generator a component also chosen for the Acorn atom so if you're familiar with that machine you'll know of its capabilities five display modes are available as well as three additional text modes with colors chosen from two very garish palettes outside of spreadsheets and word processing this would be a weakness in the dragon when it came to gaming even the ZX Spectrum was turning out better visuals with its incredibly low price point and trademark color clash manic miner for example running black and white on the dragon 32 and that's hardly a fire-breathing performance finally Microsoft basic lives inside a 16 K ROM here this was ready it was already working on the 6809 CPU so it was a natural choice when time was of the essence when our dragon hit the stores it really did seem to hit a sweet spot over 40,000 units sold before the end of 1982 55,000 units by the end of February 83 175 pound price tag seemed to set it below the more expensive BBC micros while still being affordable compared to to the likes of the ZX spectrum in an altogether more professional package consumers really did seem to like it and high street retailer boots estimated that a third of all dragon sales came from their stores and sales may well have been higher dragon data been able to keep up with the supply many retailers were unhappy with the lack of stock but the evidence suggests that supply was very much outstripped by demand in those crucial early days and especially around that 80 to christmas period the line from boots in that they had enough was from an interview from dragon user magazine a publication whose very existence relied on the success of the dragon so we should perhaps take that with a pinch of salt [Music] okay let's test out our power board we'll plug the transformer into the power socket with the power board disconnected from the system board and then with the multimeter will check the voltages and that does seem to be a problem as we work along the cable we're getting a 12 volt reading and also a 5 volt reading but our negative 5 volts is missing and that's a big problem our RAM chips need this and they're very sensitive Souls indeed without it they could be damaged and there's a chance that may have already happened let's see if we can trace back and understand the source of the problem then with tracks as big as we have on the dragon it's quite easy to follow with the naked eye following the track it goes from the negative 5 line on the cable to this resistor and then directly to the 70 905 voltage regulator the datasheet for this regulator tells us it's capable of outputting negative 5/12 or 15 volts and that's with one and a half amps the regulator next to that is the 78 12 and that gives us our 5 and 12 volts and our readings show that that's working fine so I would hazard a guess at this point that our 79 oh five is at fault as they commonly fail or another component feeding power into the regulator such as the orange capacitor you can see there in the middle of the board which is another common point of failure one way or another will figure it out [Music] and so upon entering the Dragon appears to be our first problem here on the Power Board our voltage regulator is given up on life and we need to get that swapped out there may well be further problems the capacitors I think we should replace just as a form of preventative maintenance especially these ones nearest the heatsink there's a lot of heat emanating from that he sink and over three decades they no doubt will have started to dry out so we'll get that serviced and hopefully we'll get the right voltages coming out of it with our negative 5 volts returning I know that the RAM in this system is particularly sensitive if it loses any of those lines so we may have faults on the system board but we won't even contemplate putting power into it until we know we've got the right voltages coming out in fear of doing even further damage join me soon in part two when we'll see exactly what the situation is and if we can get this repaired if you're new to the channel take a moment to subscribe so you don't miss out on that episode thank you for watching and take care [Applause] [Music] if you enjoy my content and would like to toss a coin into the hat to support the cave then check out patreon.com/crashcourse Meinke and during the official cave dwellers you can see on the screen now thank you for your support [Music] Oh [Music]

Channel: RMC - The Cave

Views: 58,381

Keywords: dragon32, wales, dragon64, trash to treasure, computer history, repair, refurb, retro man cave, nostalgia, retro, fix

Id: 1mgeeG_1qIs

Length: 14min 11sec (851 seconds)

Published: Thu Apr 04 2019