Pippin but no togs
At that stage, Pippin consisted of little more than a motherboard wired up to a keyboard, but it was sufficiently complete for Richard Wadman, Clarke's marketing manager, to begin promoting the micro to journalists and to potential software developers. Wadman would go on to write the Dragon's Basic programming manual.
The Mettoy board approved Clarke's plan, and PAT was asked to oversee the initial production run. Newport-based Race Electronics was contracted to manufacture the first batch of Dragons.
It's unclear quite when Race began punching out machines. However, after production had begun, it was decided by Clarke, now head of Mettoy subsidiary Dragon Data, that the machine would need to ship with 32KB of memory, double that designed into the prototype.
It is said that the change was prompted by the arrival of the 16KB and 48KB Sinclair Spectrum, both of which were cheaper than the Dragon's planned £200 price point. Undoubtedly, Clarke figured the Dragon's full-size keyboard and tough plastic case would make the premium over the £175 48KB Spectrum seem reasonable, but not if the Dragon only shipped with 16KB. Doubling the amount of Ram would also help the Dragon compete with the BBC Micro, by early 1982, also on the market.
More Ram, please. Designed for 16KB, early Dragons gained an extra 16kB daughtercard before release
PAT's motherboard layout wouldn't accept the extra Ram chips, so the first 10,000 machines, the initial production run, all required a 16KB daughter card to be fitted and wired up to the main board.
The author's Dragon 32 - purchased for Christmas 1982 - contains board number 9977 complete with "piggy-back" memory board.
Microsoft's Basic code didn't incorporate lower-case letters: these appeared on screen as reverse-video capitals, though they printed correctly through the not-quite-standard "Centronics-type" parallel port.
The Dragon 32 supported the customary video output through a TV modulator, but it also had a composite video five-pin Din port for a monitor. Other Din ports were used for the two analogue joystick connectors, and for the obligatory cassette I/O. The Dragon had a Rom cartridge slot that filled 8KB of the 64KB memory map.
Members of Dragon Data's 1983 R&D team: (L-R) Duncan Smeed, Jan Wojna and John Linney
Picture taken in 1985 after they had joined Thorn EMI
64KB? Yes, the Dragon's memory map was plotted across that full range. Only the first 32KB was mapped onto the Ram chips, after which came the 16KB Rom chip then the Rom cartridge allocation - preventing cartridges being hot-swappable - the PIA chip registers, the SAM chip registers, and eight bytes of reset vectors.
Next page: The belly of the Dragon
Re: You've made a happy woman feel very old
'The Girl With The Dragon Thirty-Two', eh?
You've made a happy woman feel very old
This machine is where it started for me. If it hadn't been the Dragon then it would have been something else, but this was the first machine on which I cut any code of any sort, for which reason I feel very kindly inclined to it.
Memories of the Project Leader
I was the project leader for the Dragon 32 at PAT, or Patcentre as is was then known. I thought you might like to know what I remember of that time.
I remember spending a lot of time talking to a really helpful Motorola chip salesman called Robin Saxby. Yes, the same guy who later ran ARM and is now Sir Robin.
We certianly did not copy the CoCo. It was not really available in the UK because it had an NTSC video system which would not work on UK TVs in those days. The Motorola application for the SAM chip (synchronous address multiplxer) showed a complete home computer to which the CoCo was identical. We made numerous improvements to this app note. We included a real A/D and D/A convertors for generating the FSK signals used to store programs on tape. We added a parallel printer port and used the same chip to scan the keyboard. We had a separate power supply PCB which also contained the TV modulator. It was a single sided PCB so it saved cost but also allowed variants to different TV standards to be made cost effectively. We made a SECAM variant for France and also an RGB and US version.
I do not rmemeber Motorola suppying a BIOS. Microsoft wrote the Basic interpreter, which was essentially the same as the one they licensed to Tandy but with a few add-ons, but you were expected to create all your own peripheral drivers - a situation unchanged to this day. It was these drivers that Duncan (Smeed) wrote. I do not remeber the keyboard speed up being his alone. The nromal way to scan a key board is to activate a row and read the columns to see if a key has been pressed and repeat that for each row. Of course, most of the time there was no key pressed and this routine just wasted a lot of time getting a no key preessed result. We realised that becuase we had used the same chip to scan the keyboard as drive the parallel printer port, we could do one thing the CoCo could not, and that was activate all the rows at once. If you do this and then look at the columns, in one go you get to know if there are no keys pressed, the most common situation, and you can exit straight away. If you find a key has been pressed you scan as usual to find which one. This is what saved the time.
The PAL output had nothing to do with the CoCo. PAL was essntial for it to work on UK TVs. Few if any had SCART sockets so you had to create genuine PAL. Persuading a chip designed to make 525 line 60Hz NTSC to make 625 line 50Hz PAL instead is a non trivial exercise and needed a lot of descrete logic - ASICs were in their infancy then.
Two weeks before the official launch, the Spectrun 16K came out. The piggy back RAM PCB was designed, tested and ramped up for production in that two weeks. Later we used a bunch of Siemens 32K RAM chips that consisted of two 16K RAM chips literally piggy backed on eachother and later still upgraded the main PCB to 32K then 64K.
We then worked on the disk drive unit which was abandoned when Tony Clarke left and all development work went in house. What is probably not well known is that at the same time we were working on the successor to the Dragon, code named Draconis. This used a Motorola 68K processor and a very powerful graphics chip from NEC. Along with OS/9 as a true real time executive, this would have beaten the PC hands down as a business machine. But for the vagaries of the home computer market, we might all be using Dragons today.
I had one of those!
Somehow spending 4 hours typing in games, then finding out you mis-spelled "peek" at line 827, before you could play them created an enormous feeling of accomplishment. This stick in a disc and off it goes malarky we get these days is for noobs I say.
Don't think I'd want to turn back the clock, but somehow proud I was there at the time.
Re: It was *garbage*
What are you talking about? It worked fine. Sounds like you took a perfectly good computer back because you made a typo somewhere. I guess it's the 80s equivalent of blaming the compiler :)