| Posted By
TLC
on 2007-10-28
17:28:25
|  Drean Commodore 16 details -- finally...
Finally, I managed it to get hold of a Drean Commodore 16... this is the PAL-N version of the C-16, assembled and sold locally in Argentina. I've just got the computer up and running (it was known not to work when it was sold), and will yet have to finish disassembling/cleaning/assembling the physical parts before I could call this deal finished, but here are some details nevertheless.
-- PAL-N is basically normal PAL, with a different (lower) color subcarrier frequency.
-- In the Drean C-16, you can find a 8365 TED instead of the usual 8360.
-- The oscillator runs off a crystal of 14.32822MHz -- a bit faster than NTSC's 14.31818.
-- The motherboard is otherwise a regular NTSC C-16 motherboard, with the usual European Kernal installed.
Speaking of the 8365 -- my first impression is that it's a "regular" 8360, and they only modified one parameter, the constant which is used to divide the oscillator clock to obtain the processor and the dot clocks. To get the CPU single clock in the 8360, in PAL, one would divide the crystal freq by 20, and in NTSC mode, by 16. In the 8365, both dividers are the same, 16.
As consequences:
-- When switching between PAL and NTSC mode on the 8365, one would get visible picture on a PAL/NTSC capable TV, at least in black and white (unlike regular 8360-equipped machines, where either the PAL or the NTSC mode is displayable on regular tv's, but not both).
-- The color subcarrier won't, but the color encoding should change according to the PAL/NTSC bit (subcarrier freq is the same). With an NTSC crystal, the 8365 should also be capable of providing standard NTSC signal.
-- With the PAL-N crystal installed, colors are obviously only seen on PAL-N capable TVs or such PC tuner cards. The color palette for PAL-N mode should be similar to regular PAL colors, but the color resolution is worse, 2 pixels vs. 1.6. (In other words, in this respect PAL-N is NTSC's color resolution with the PAL palette).
The CPU (single) clock of the computer is the highest amongst all known TED based computers; it's about 0.895514Mhz. As a consequence: as it's a "regular" PAL machine with a slightly faster clock, all European C-16 software should work on the PAL-N C-16, but floppy fast-loaders may fail to work. European stuff messing with the PAL/NTSC bit should fail, too (but other tricky stuff, like sideborder-removing should work... I'll yet have to test those, but I don't expect anything irregular...)
...I guess that's all at this point...
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Posted By
Degauss
on 2007-10-29
07:29:56
| Re: Drean Commodore 16 details -- finally...
Wow! Good work, TLC!
But about the Clock-Frequency: Any Idea why they changed it? Was there a necessity to do this? I believe everything that is very timing-critical should behave a bit differently on that machine, probably not only fast-loaders...
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Posted By
Luca
on 2007-10-29
16:20:13
 | Re: Drean Commodore 16 details -- finally...
...and I'm waiting for great pictures by now! Great job Levente! 
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Posted By
TLC
on 2007-10-29
16:26:45
| Re: Drean Commodore 16 details -- finally...
Degauss: thanks, it's been a long, but not at all that hard "project"... :-D ...I just kept my eyes open (for the last couple of years), as I knew the chance should come sooner or later as eBay gets more and more popular.
As I guess the machine won't even be hard to emulate (better said: darn simple, with all those things known by emulator writers today), the only thing needed is/was to finally obtain a computer (that nobody seemed to have inspected closely yet, as nobody had one), make notes of some info, make some simple tests -- all in all, to find evidence about a couple of anyway simple things. And after that, why not emulating it... it definitely isn't a well known platform, but it's part of the history, and it was a production machine anyway... IMHO a very interesting production machine, but that's probably just my point...
(BTW: as I read, in Argentina, the situation has been slightly similar to that of Hungary... I mean, there were no real local software resellers that would have sold the known software titles. Instead, mostly everything, including a considerable amount of the computers (excluding those manufactured locally) were grey-imported to the country... The folks there spreaded pirated software from hand to hand, similarly to how it went in Hungary in the middle and late '80s... I wonder why didn't evolve a scene there, as it happened here... (unfortunately, I don't know the answer), it would have been interesting to meet software titles and demos made for effectively the same machine, from a country which/whose folks are that far from here so probably have their own great names...  ).
As to why Commodore had to change the clock: I think they just wanted to support PAL-N with as few modifications as possible. In the simplest case, for PAL-N to work, they just chose a crystal whose frequency is (similarly to how it's done in the PAL and NTSC models) 4 times the color subcarrier frequency of the tv-standard.
PAL-N's color subcarrier frequency is almost like that of NTSC's (3.582055 vs. 3.579545, the difference is almost negligible), but is higher nevertheless. That's why the PAL-N computer is a little bit faster than the NTSC one (assuming the same clock division chain). In other words: the only reason why the computer's speed doesn't match the speed of either the PAL or NTSC model, is the different television standard to be supported (whose color subcarrier frequency differs from both PAL and NTSC).
As to how much is the difference:
PAL --> NTSC: ~=0.92%
NTSC --> PAL-N: ~=0.07% (very small)
PAL --> PAL-N: ~=0.99% (not that small, but still almost unnoticeable, except for critical cases)
A quick test has shown that the 8365 generates 57 cycles per line, and 312 rows per frame in PAL mode (similarly to the usual PAL machines)... the overall speed and framerate is slightly higher than that of the European machines, but as long as the computer won't have to keep up syncing to the "outside world" (ie. the only known "time" it knows about is its own time), and unless there's some heavy modification in the 8365 that I'm not yet aware of, it should run all time-critical code well... I haven't made any further tests, as the computer is still in pieces, I just connected a keyboard to it to make those first-tests.
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Posted By
Csabo
on 2007-10-29
21:48:39
| Re: Drean Commodore 16 details -- finally...
Interesting read, TLC. Even though probably there wasn't a full-blown scene there, I'm certain they had their share of homebrew applications. It would be very cool to find some of that stuff, if it (still) exists.
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Posted By
Degauss
on 2007-10-30
11:41:30
| Re: Drean Commodore 16 details -- finally...
Maybe somebody posted it somewhere else, but: How many of those have been sold? That would give a clue if there was a homebrew-software-scene...
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Posted By
C16 Chris
on 2007-10-30
18:26:25
 | Re: Drean Commodore 16 details -- finally...
I found the drean commodore 16 with the serialnumber 535 in the web.
http://www.a-clasico.com.ar/compu_archivos/drean_c.htm
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Posted By
JamesC
on 2007-10-30
22:07:39
| Re: Drean Commodore 16 details -- finally...
Is it my imagination, or do the serial number stickers look suspiciously like the stickers used on PET/CBM equipment assembled in West Chester?
Even the typeface used for the actual serial number imprint looks very similar.
I wonder if these were shipped to Argentina mostly complete, with only minor assembly required locally... such as screwing the case closed.
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Posted By
Ulysses777
on 2007-10-31
10:00:44
| Re: Drean Commodore 16 details -- finally...
I think that serial number typeface was used on a lot of stuff. It's used on the England-built Commodore 264 machines, and I have an Atari XEGS here with the same S/N typeface.
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Posted By
TLC
on 2007-10-31
17:49:25
| Re: Drean Commodore 16 details -- finally...
Mine is #409...
Looks like, the boards were fully assembled before shipping to Argentina.
The board had lots of cold solder joints that looked like having had been fixed by someone (bad soldering points that get loose with dilatation). ...I'd doubt that it was assembled in Argentina, but looks like an early piece of a production run anyway...
The plastic box looks like having been manufactured by Commodore and then imported, too... from small signs here and there, it's certain that they have been die-casted on the same die as the other (German C-16's) box I have here.
From the other hand, serial number stickers are stuck on three independent parts (the bottom of the box, the motherboard and the keyboard); from that I'd say they did the numbering where they assembled the parts together.
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Posted By
Gaia
on 2007-11-03
16:06:58
| Re: Drean Commodore 16 details -- finally...
Levente: are you going to make a ROM dump? That'd be interesting (though I do not expect major differences).
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Posted By
TLC
on 2007-11-03
17:35:03
| Re: Drean Commodore 16 details -- finally...
It has a usual PAL rom, at least, according to the part number of the chip.
I may make a rom dump of it nevertheless.
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Posted By
TLC
on 2007-11-03
17:50:30
| Re: Drean Commodore 16 details -- finally...
Finally, the computer is in one piece and so I could test some code.
As expected, PAL stuff worked flawlessly. I yet need to bring the external memory expansion module from my parents' house to test more (tricky) programs; as of yet, all I could test were C16-compatible programs (4Ever2k3 C-16 compo stuff rules... ). I had the interlace routine (provided by Bionic and István Varga) at hand, which I considered rather tricky and system-dependent, at least that ran like a charm.
Megaload (that I also had at hand) didn't work, just as expected.
Today I received an e-mail from the eBay seller I had bought my computer from; he's going to sell more machines, including an other Drean Commodore 16 which looks like being in pretty neat physical condition (as opposed to mine which took considerable time to get back into shape, and it isn't that perfect even now). I guess he's gonna sell that on eBay, but if someone's interested please drop me an e-mail and I'll forward the pictures/ad I received to your mailbox.
BTW: looks like they changed the outfit of the machines during the production time... the machine he sells looks different from the one I've bought (or I've ever seen so far). I'm really wondering how many units (in how many "series") they really produced.
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Posted By
JamesC
on 2007-11-03
22:40:24
| Re: Drean Commodore 16 details -- finally...
the machine he sells looks different from the one I've bought (or I've ever seen so far).
Then PLEASE post the pics that are of the "different" machine. A C16 is a C16 as far as I've always known. (Other than the prototype machines, that is.)
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Posted By
TLC
on 2007-11-05
05:49:53
| Re: Drean Commodore 16 details -- finally...
Dear James (the C),
As a reply to your kind request, hereby I inform you that you can see (or bid on) the machine here:
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=160176415283
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Posted By
TLC
on 2007-11-05
06:00:32
| Re: Drean Commodore 16 details -- finally...
I'm currently abroad, so I can't take/post pictures (and even if I could, there's not much use in taking pictures of that machine anyway; the computer I bought isn't in that great physical condition that it would worth taking pictures, except for the sake of an example until someone comes up with better ones). As said above, the computer got offered at eBay, so anyone interested would have the chance to bid on it; there's no need/use to contact the seller directly in e-mail (to make a deal with him outside eBay) anymore.
To make it clear: there shouldn't be huge differences between my (or other) DC-16s and the one currently offered. Mine looks like the previously known DC-16 pictures, whilst this one looks to have different (probably embossed?...) decals.
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Posted By
JamesC
on 2007-11-05
07:47:56
| Re: Drean Commodore 16 details -- finally...
The one listed on Ebay currently, appears to have a textured nameplate like my Plus/4s and 1551s have. When looking at the second photo (with the television) I see a little bit of shadow under the name "Drean".
The "8" key has probably ben replaced, as it's a lighter shade than the others and I do not see any color names on the front of the key.
Am I missing something here? What nameplate does yours have -- textured metal, or flat adhesive (vinyl) nameplate?
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Posted By
TLC
on 2007-11-05
16:25:16
| Re: Drean Commodore 16 details -- finally...
Mine is rather like the one posted earlier on here (http://www.a-clasico.com.ar/compu_archivos/drean_c.htm)... the nameplate on the computer is a rather grey-ish, thick-ish but otherwise flat plastic decal. The "ENC." (Power) text on the up/right side is painted in silver on top of a (n also) painted, light brown-ish background. (Until I can take pictures, here's this one: http://i24.ebayimg.com/07/i/000/ba/26/4451_1.JPG )...
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Posted By
TLC
on 2007-11-10
19:10:53
| Re: Drean Commodore 16 details -- finally...
I made some photos -- you'd find them here:
http://coroners.no-ip.hu/dc16
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Posted By
IstvanV
on 2007-11-11
07:54:12
| Re: Drean Commodore 16 details -- finally...
Regarding emulation, the slightly higher clock frequency is of course an easy change (with plus4emu 1.2.3, just set the video clock frequency to 17910275 - since it is still divided by 20, it should be OK as long as programs do not mess with the NTSC bit in $FF07), but the NTSC bit is more tricky, at least for me, since there are many code parts that assume the standard 8360 behavior; in the end, it is solvable, but I do not know how to avoid a minor slowdown.
The pictures look interesting. While it cannot be seen if the interlace works with colors, I would assume that it does. Of course, another simple demo, that also uses NTSC to increase the horizontal resolution as well, would not work at all.
I have some simple TED test programs that I use to compare emulation with the real machine, but other than the different clock division and color subcarrier, it is probably not different from the other PAL machines.
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Posted By
Luca
on 2007-11-11
10:14:04
| Re: Drean Commodore 16 details -- finally...
I added some entries in the Hardware section, regarding the Drean C16 and the MOS 8365, thanks to the pictures Levente has got (thanks!). Feel free to add more infos and material.
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Posted By
Luca
on 2007-11-11
12:40:22
| Re: Drean Commodore 16 details -- finally...
I just won a MOS 8365 on ebay.it (claimed to be a working on, I'll see).
Does someone know if MOS 8366 has different features?
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Posted By
TLC
on 2007-11-11
13:23:31
| Re: Drean Commodore 16 details -- finally...
Luca: it's nice, thanks!
István: yep; personally, I can see three points where differences might or should be addressed in an emulation... the first one is the easiest, the different base clock. Second, the single modification of the clock divider (simple in principle, might be tough in practice, as you yourself admitted). ...BTW I'm almost sure that if I'd take this 8365 TED and put in into an NTSC machine, the computer would boot up just like a regular 8360-equipped NTSC one. ...I'll do that test someday, I have an NTSC C-16 (in fact a modified European one, but that makes no difference as long as the RF-modulator is unused), but unfortunately not at hand ATM. Third, and only for display emulation mode: PAL-N should have slightly worse horizontal color resolution than PAL-G, so the colors should be more blurred horizontally. (This is clearly seen in an NTSC vs. PAL C-16 test, and as PAL-N is more likely NTSC in this subject, the blur should rather be NTSC-alike as I guess).
I'm personally very interested to see how much more blurred the color screen of the PAL-N C-16 is... and it's not just the analysts point of view (...rather, it would just be cool to see the classics and also newer stuff in native PAL-N colors, once I have this machine :D ). ...Obviously, I could not "see" it yet, as I have no PAL-N capable displays. I should obtain or buy a PAL-N decoder, but my attempts have (so far) failed. The gadget that I'm aiming to get hold of is something that decodes PAL-N in a regular analog way, and can be connected to the analog RGB input of the SCART socket of this TV. With that, the comparison could be real. However, I haven't found anything like that at Internet shops yet; the gadgets found were all digital ones instead, and I avoid those (as I don't feel that those would give an appropriately "real" result). ...Will possibly end up building one from scratch... there are at least a handful of useable PAL-decoder chips out there, I just didn't want to fiddle with this detail myself.
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Posted By
TLC
on 2007-11-11
13:38:55
| Re: Drean Commodore 16 details -- finally...
Luca: whoa! That's is a real surprise!
I've never seen a 8366 myself, nor have info if it had been produced. According to this document: http://www.zimmers.net/anonftp/pub/cbm/documents/chipdata/csg.chips.info , the 8366 is the PAL-M version of the TED. PAL-M is, AFAIK, only used in one country: Brasilia. Technically, PAL-M it's a similarly "mixed" standard as PAL-N is, but in a different way. PAL-M is like NTSC-M in all major details (number of lines per frame and frame frequency), except for the color encoding, which is PAL. A PAL-M C-16 should probably run off a crystal with a frequency slightly below 14.31818Mhz, have an NTSC kernal chip, an NTSC RF-modulator, and the 8366 TED should have the PAL/NTSC color encoding selector fixed to PAL (regardless to $ff07 bit 6).
Does probably someone have info if there was a localized PAL-M C-16 / C-116 / Plus/4 version for Brasilia?... If there was, there's yet some white area on our map... ...I know there was such C64 version, but AFAIK that didn't need a different videochip to be manufactured.
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Posted By
Luca
on 2007-11-11
13:57:55
| Re: Drean Commodore 16 details -- finally...
I'd found this MOS 8366 searching for infos about MOS 8365, and encountering this from Argentina on my way. As you can see on his site, he had a C116, a C16 abd a 264 which he used to call Plus/4.
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Posted By
IstvanV
on 2007-11-11
14:38:46
| Re: Drean Commodore 16 details -- finally...
The different clock division is still not a major issue, at least as far as the effects on speed and sound pitch are concerned, since it is handled in one place. The display effects are more interesting, since the NTSC bit should change the color encoding (i.e. +/- 33 degrees phase shift, different burst phase, and phase alternation), but not the dot clock and sampling of pixels. Anyway, it is more or less straightforward, just requires changing the already quite messy display code in many places.
While I do not emulate different amounts of horizontal color blur even for PAL vs. NTSC (I have never actually seen the NTSC picture anyway), it would be basically just adding a third GL fragment shader for the PAL-N mode, and changing the color blur as needed (it is essentially a 4x2 FIR filter for PAL, and a 4x1 one for NTSC; the sample positions can be fractional).
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Posted By
TLC
on 2007-11-11
16:35:06
| Re: Drean Commodore 16 details -- finally...
Have found something interesting... this one:
http://ulegan.de/pal2rgb/pal2rgb.htm
This is an article and plan about building a PAL to RGB converter circuit. It's not PAL-N capable, but a quick look around the TDA8362 chip revealed that it should be simple to add that functionality (the TDA8362 by itself is capable of PAL, NTSC, PAL-N, PAL-M, if the proper crystals are supported, and even SECAM, with an additional chip). I'm sort of happy, to put it that way... :D For a short moment I was still hesitating whether I could obtain the chips, but after a few searches at various Hungarian electronic component resellers, I know that even this detail is positive. The page even supplies a PCB plan... will have to order a PCB from some local manufacturer (it's a single sided PCB, I won't even expect it to be expensive), buy the chips, and here we go...
...Well, if I only knew, where on Earth will I find a suitable, 3.582056Mhz crystal... :-DDD
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Posted By
Luca
on 2007-11-19
09:02:17
| Re: Drean Commodore 16 details -- finally...
Oh, the MOS 8365 I've bought on eBay.it is here finally! It's tagged "MOS 8365 2885", and on the back "korea ah262120 ncap 3".
How to test it in a secure way? Put in and go?
PS: I also receive a MCM68766C, claimed to be "proto-rom pin compatible with original 2364", an EPROM similar to the C64 BASIC rom...a prototype maybe?
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Posted By
TLC
on 2007-11-22
05:54:48
| Re: Drean Commodore 16 details -- finally...
Putting the 8365 to a regular C-16 or Plus/4 should be fully safe. You most probably won't get a stable screen if you put it into a European machine, though (operating frequencies will be off).
Your best bet to see it in operation should be an NTSC machine (in NTSC mode, the 8365 should work just as a regular 8360). A PAL machine, whose crystal had been replaced to an NTSC 14.31818MHz one would be equally good, but replacing the crystal needs soldering.
To "fully" reproduce a PAL-N C-16, you'd also need a standard PAL-N crystal (14.32822MHz).
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Posted By
TLC
on 2007-11-22
08:10:43
| Re: Drean Commodore 16 details -- finally...
About the EPROM chip: back then, mask-programmed ROMs, microcontrollers and other programmable chips were pretty common. As development would have been hard and slow with mask-programmable ROMs, the manufacturers usually offered EPROM-versions of the respective mask-programmable chips (you can check, for example, the Intel 8048 microcontroller, whose EPROM-version is the 8748 and so on)... maybe, the MC68766C is a similar equivalent for the mask-programmed 2364.
(Back then, manufacturers rarely used EPROMs in production machines, as they were expensive).
As far as I know, by that time the industry just had a standard pin-out for ROM and EPROM chips, and only Motorola and MOS manufactured chips like the 2364 (which is a non-standard, 24-pin 8k*8 ROM, unlike the "standard" 2764 which had 28 pins). Later they implemented standard pin-outs, too... (the 23128, the 16k*8 bit mask-programmed ROM that you'd also find in the Plus/4 is fully pin-compatible to the standard 27128 EPROM, at least).
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Posted By
TLC
on 2007-11-22
09:38:31
| Re: Drean Commodore 16 details -- finally...
In the meantime, I got the pal to rgb converter box to, well, at least semi-working. ...Got the PCB that I had ordered last week on Monday, bought most components and drilled the holes on the PCB on Tuesday, and could first-test the box yesterday late in the evening. Will yet have to find out why the sync part doesn't work (should be simple). Things to be done: yet more modifications (NTSC, PAL-M, eventually SECAM support, S-VHS support and things like that), putting everything into the box, mounting the connectors (about twice the work that I've put into the stuff already, approximately), tests, then testing it with the DC-16 in PAL-N. The hardest part (left) is to obtain a 3.582056MHz crystal; if you happen to know a source, please don't hesitate to let me know about it (as I'm currently stuck on that detail).
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Posted By
Thierry
on 2008-03-31
01:01:45
| Re: Drean Commodore 16 details -- finally...
Hi to all , im from Argentine , look this site , www.retrocomputacion.com ,
There are many people in the forum that they them can help, in Argentine the commodore 16 were common and there is very much software here to share..
my Drean Commodore 64
[IMG]http://i31.tinypic.com/2cr7yf7.jpg[/IMG]
[IMG]http://i25.tinypic.com/2vws8oy.jpg[/IMG]
best regards -..
Thierry ---
Thierrykurtout@hotmail.com
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Posted By
Luca
on 2008-05-07
10:03:29
| Re: Drean Commodore 16 details -- finally...
Very nice images of Drean C16 on that site, Thierry!
I still wonder of there are proper argentinian releases for c16/+4, the only one I know is Jack Ataca...
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Posted By
Luca
on 2008-05-11
05:07:49
| Re: Drean Commodore 16 details -- finally...
What a awonderful collection! Are those games and programs totally similar to the original releases, or do they show some changes?
So, what are you waiting for? I'm here with open hands!
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Posted By
Sidius
on 2008-05-11
07:11:00
 | Re: Drean Commodore 16 details -- finally...
Now, I've not still come at all to test them everything... 
But if I've done this, then you will be the first one which finds out the result!
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