New video...

I've uploaded a small video showing the current state of the C64 version. I suddenly realised I'd been sitting on it for ages and no one had really seen it.

You'll notice its not quite right, as background stuff isn't animating, and bullets aren't quite right. Still, it looks pretty, and the multiplexor holds up pretty well too!

Come and get it!!

I've now added the C64 frame work (and sample app) to the downloads links on the right, scroll down a bit and you can't miss it!

So to recap what I've given you to play with in the framework....

Initialisation, mainloop and interrupts all setup and ready to go.

Production quality multiplexor

Three seprate switchable sorts.

Simple collision detection system

General sprite animation system.

Game based keyboard and joystick routines.

Simple player control framework.

Lightning fast 8x8bit multiply routine.

Simple random number routine.

Built in MMC64 FAT16 file loader.

Simple example platform engine showing the framework in action.

And there you go. As a little aside, the example also has a byterun decompression routine built in that you can use as well. Its all very simple really, but if you have any questions (or find any bugs) feel free to bug me about it.

Hope its of use to you and gets you going on your next great game!

MMC64 loader finished

I've now completed V1.0 of the loader complete with PRG file loading. Its shot up a little to about 900 bytes but it's now functionally complete. The only thing missing (which isn't vital just now) is error checking on initialisation. Its not important because if youve done a game thats supposed to load from an MMC card and its not there, then you have bigger problems! I've just ordered a retro replay so I can check all is well with that too (okay, okay...Coz it's cool...)

So tomorrow night I'll try and knock up a new downloads page somewhere and get all this up for you lot to play with. I'm not sure what I'll work on next but I like the idea of using the MMC card loader in the C64 version of XeO3.

I also want to do a proper Super CPU version of the loader so I can start playing more with that. I'd love to see how many software sprites I can pile on a bitmap screen, and I'd love to try that Lemmings idea too...

MMC64 cleanup

I'm putting the finishing touches to the MMC64 loader and making it work with more files. I've also shrunk it down a fairly sizable amount, with the code shrinking from 1,236 bytes down to 828 bytes (sofar) and the data block has shrunk from 624 to 568. While doing this I've optimised the load a bit so that the bulk of the file gets loaded directly into the destination rather than going via a sector buffer, which should make it twice as fast - in theory.

I'm pruning down all the "nice" bits and making it a bit more hard core C64 only - something I'll reverse when I do a SCPU version in the future. So for example while file sizes can be a full 32bits, we know a stock C64 will be less then 64k, so only work in that size.

That said I've tweaked quite a bit of it so it is a little bit more robust, but it will be likely to fall over if you use it wrongly, which isn't a problem as its not designed for a file browser, but a game that KNOWS what its loading. I've also decided to ignore long filenames, because again a game doesn't care! In fact, chances are you're filenames will be something like L1\1.PRG or LEVEL1\DATA.PRG. But this for a game is fine.

I haven't done a directory search yet and I might not for the 1st release as that'll put the size up again, still we're now sitting at 1,396 bytes total for code and data which is pretty good indeed. So for now you'll either put the game directory in the ROOT or specify something like GAMES\XEO3\LEVEL1\MAP.DAT. I have also yet to do PRG loading, so that it gets the 1st 2 bytes and loads it into the correct address - that will complicate things a little, but it should be okay.

I should also say I expect SAVING to come in later versions as well as its not hard to save to these things, so high score tables or editors can make use of the storage medium as well - which will also be pretty handy. Also...I do not disable interrupts, so technically speaking, you could be playing music, scrolling the screen or whatever while you load things. Also means the SCPU while taking time to load a meg of data can play music and display a loading bar or something!

So... only a little more to do for a 1st version, then I'll knock up antoher web page and post everything for whoever wants it.

Success!

I've now managed to load a file from the MMC64 given a full path+filename! Very cool indeed. It's a shame that you can't page in a ROM that has this functionality built into it. My plan of doing a Plus/4 MMC card was to have a built in ROM with lots of extra features built in like the Kernal, that way adding loading to a game would ultimately be very cheap and you wouldn't need to add all this code.

Still... thats a future thing, for now I need to test this code and load up lots of other files and make sure it all works. Im pretty sure it won't be terribly fast either as its pretty noddy code, however keep it simple and get it working - THEN speed it up and make it impossible to read.

The code is sitting at 1,860 bytes long (1,236 code and 624 data) so it would be nice to shrink this too. If the code can fit inside 1k that would be perfect I think. RAW loading is pretty simple, but including path searching and other features will push up the code space a little.

Anyway... all this aside, it's now working and is pretty cool. As a side note it should now be possible to load large files for my SCPU work; very neat.

MMC64 Progression...

I've progressed quicker than I figured I would and have almost got files loading from it. It also supports directorys and will load a file from a full path+filename (just about). It only uses 8.3 filenames so far, but I suspect it will get expanded to do more in the future.

It takes arond 2k to add this although 600 bytes of it is data and a sector buffer. I suspect this will shrink a little once its all working properly, but to have fast access to 4Gb's of data is probably worth the extra space.

I also plan to put in a recursive directory search, allowing you to search for a game directory and then load from there. That means people won't be forced to put everything in the root directory.

I will also write a full Super CPU version allowing you to load megs directly into memory, and MUCH quick than a floppy could.

Life after floppies....

I've spent a little time trying to chat up my MMC64, but it just won't respond to my tender words, at least I wasn't having much luck until about 5 minutes ago. I was following the documentation completely - cut and paste actually - but with very little to show for it. It then occured to me that since I'm loading from it, it must already be enabled and ready to go. So I've dispensed with the full initialisation and jumped straight in with sector reading, and what do you know! It works! I'm not quite sure what would happen if you have to re-initialise the thing as I can't seem to get that going at all, but as long as the cards in and you've just loaded the main program from that, its all funky.

For a first pass, not having any error state is probably fine, after all its not like you have to swap disks (err...MMC cards) during a game or anything, and if you remove the card then its probably your own fault. Still sometime down the line doing a better fault tolerant system is desirable - but lets get the bugger working first! I still expect this to be released in V1.1 of the framework, but its good to see it shouldn't be too difficult.

I've also added a simple animation system to the framework even though I said I wouldn't. I figured you can always rip it out, and in the end the ones I write are almost exactly the same over and over again so sod it. This means theres now the multiplexor, a few sorts, basic collision, animation, joystick and keyboard input and a very simple test app - which is a good start. Actually, theres 2 test apps. The Frame work has code to bounce sprites around in a simple manner, and then theres the playformer framework which gives a little more realistic usage. Still the more the merrier.

I'll now have to do another web page to download all this rubbish, and expand my wiki page to have some simple documentation...and I mean simple...

C64 framework V1.1?

I've thought of one more thing I'd like to add, but its not a quickie by anymeans so I'll leave it till version 1.1 so that I can get this version released. After speaking about using the MMC card as a loader, I suddenly realised that it would be awesome to have a proper file loader built into the framework. That way these no excuse as to not use it, and it'll make development MUCH simpler. Simply bung your files onto an MMC card in a folder or something, then load them - how simple would that be! It might also mean we would start getting some more games that load directly from the MMC rather than floppy/tape, which would be very cool.

I also suspect V1.2 will be when I start to add remote debugging features through RR-NET. As I've mentioned in the past I do have the beginings of a remote debugger on the Plus/4 and would like to get that onto the C64 but using the ethernet adapter rather than the user port. Although since the upload/download part is prett much GetByte()/SendByte() I can probably have both in case people don't have an RR-NET. It would be good to get a proper devkit again as I was reading about the old PDS system I used to use and starte getting a little homesick for it...

You can read about it HERE if you wish although its in spanish. HERE'S a translated version via Babelfish. It really was an amazing little system and I miss it hugely.


Oh and as a little side note, I've managed to get WWW.XEO3.COM again. I'd let this expire and some bugger pinched it which is why I went to the .ORG, but I've now got it back again so I'm happy.

C64 framework and sample

I've now finished the sample app that I was doing for the frame work; well, as much as I intend to. As you can see its a platformer in bitmap mode, and you run around collecting the bombs. Its basically a simple version of the first level in bomb jack (without the baddies). It uses the built in player-2-sprite collision routine as Ive been lazy and done the bombs as sprites, but it does help to show how to use the framework better. Also remember that I've only really spent a couple of days on the sample, so dont expect too much.

I've done it in bitmap mode because platformers should never really be restricted by character count or colours, so having a full bitmap is nice. It also let me have a pretty background, although it turned out to be harder than I thought at the time. I had to rip the bitmap off an old Ballistix floppy and then I discovered that I had stored it compressed! So I then had to rip the decompression code from Ballistix into the sample. Still it was only byte run so it was easy enough.

Anyway, with this done, I now only need to clean both up, write some very basic doc's and then upload it somewhere. Perhaps someone will even finish the platformer sample... who knows... It would be cool if you did a built in MMC loader and you could load each levels bitmap from an MMC card really quickly. I think any games you do these days should take advantage of new tech that everyone's buying, and that in turn would help sell more and move things along. If nothing uses a new bit of hardware, no one will buy it!

Last chance for anything to be added though. I can't think of anything, but feel free to suggest. I'm not sure when this will get released, but I dont expect it to be long now. Hope you all enjoy it, or at the very least have fun looking though the source...

Super CPU ideas....

Theres been several comments on the last post so let me go through them here...

First parallax scrollers. Games that have done these in the past have been limited to character blocks to do it's parallax effects and these have worked pretty well for the most part, but perhaps if you actually MASKED a full bitmap onto another you could produce something pretty special looking. Of course doing this would negate the use of the full attibutes as you would get colour clash... still dual playfields is always nice. You COULD stick to doing character based parallax and do a full bitmap scroller which would look pretty good, but not THAT much different from a stock C64 game using characters i suspect. This is what MetalDust does (I think) and its...okay... but we've come to expect games doing that kind of parallax.

Sprites. Now its true that anything I do I'll immediately load it up with as many software sprites as I can, and that I expect the screen to be crawling with baddies+effects. C64 games do this usually with lots of cheats, but if you can draw large sprites, you can push the boat out a little. However these will obviously suffer from colour clash again, which is never good. I suspect that if I arrange the bitmap better (straight rows rather than the funny character mode way) I can seriously increase the number of sprites I can actually draw. I'd then convert the screen on the fly as its copied down the VIC memory. Since the SuperCPU has a 1 byte write cache that gives me 20 cycles to get the next byte, and thats more than enough to convert the straight row format into the silly Commodore one. Of course on top of that, I now have 16bit registers allowing me to load and mask things on better, and upto 4Mb RAM (although mine has 16Mb, I think 4Mb is a good limit - anyone have less?) allowing me to pre-rotate everything at the start.

Now its also been suggested that you could do a full PROPER Lemmings game, and this is also true. You wouldn't be able to get the lemmings as the blue/white/green we all now and love, but a full white would be possible. In fact the best way (and to avoid colour clash) would be to use the full bitmap mode for the backgrounds and multiplex Hires-expanded sprites (on X at least) for the lemmings. That would have MCM resolution but it hires. Thats doable and gives a full dual playfield for drawing sprites + explsions easily. Not only that but because the SuperCPU can quickly multiplex sprites, you're only going to lose a few scanlines making this new playfield. On top of that... It only takes 7 sprites to do the playfield, leaving 1 hardware sprite for the cursor! Using the Commodore mouse you could finally replicate the proper lemmings game on the C64 - complete with the full 100 lemmings!

Lastly.... I suspect this will become a pet project and would be the ULTIMATE game for a SuperCPU, as theres no WAY a stock machine could even hope to do it.... GTA. Yup, I've been giving it some thought, and I think I could replicate the graphics engine I did on GTA1 on the SuperCPU. Im not sure I'd zoom in and out in the same way, but I think I can certainly do the perspective buildings... They may or may not be textured though... that Might be asking too much, but you would certainly get the effect GTA had of zooming around a 3D city... now that WOULD be cool....

Having a play.....

Okay, so I'm not doing my mini-game thing, I've been playing with my Super CPU instead. One question thats always got me thinking is what can you do with a superCPU that you can't do with a stock C64 (3D aside...).

Well, heres one: full screen overscan bitmap scrolling. Not using expanded sprites or anything, but using the full bitmap screen AND sprites in the side border. Now... I thought you might actually manage to do that with delayed DMA etc. but drawing into a full screen height would be virtually impossible surely, particually since you have to scroll through 4 sprites.

Well... okay... you COULD kinda do it... kindof... Imagine this...

FULL screen bitmap, delayed DMA scrolls that - great. Now how about the edges? Well, you need sprites there of course. BUT that means you've to smooth scroll through 4 sprites (2 on each side). Well no. Sprites can move in pixels after all, so just move in bytes and move the sprites in pixels to sumulate a normal scroll.

This still means you have to redraw the sprites though, and thats 4 sprites, (say) 189 pixels each. Quite a bit.... well...no...

IF you used another extra sprite on each side, then you can scroll the sprites and bring on new empty ones each frame too, then your only drawing 2 colums or sprites 189 pixels high over 8 frames (along with the bitmap) - which is perfectly doable.

Could make for a pretty cool C64 demo - standard MCM res, full screen/overscan scroller...neat. Course... since you can't change the colours very well in sprites, you'd have to pick 3 normal colours (sades of blue etc)... but still. You could also use character maps of course, which would make scrolling them much easier and would mean you didn't have to use delayed dma, as long as you double buffered the character map.

So the outcome.....A cool demo on a normal 64, and I still need to find an impossible task for the SuperCPU. It's pretty amazing what a stock machine can do if you poke it a little....


(and before you ask...no I have actually written it all, I've just been playing and know HOW to write it....)

Time for a quickie?

I've been playing with a bitmap to C64 convertor after several images I tried didn't convert very well. It seems for simple images the more complex convertors just dont gvet it right at all. Anyway, it was no more than a simple diversion but image processing is always good fun.

I've also started a little game and although I may not finish it, a sample app with realistic usage should provide some entertainment to folk. once I get a little further I'll post some piccys, but I wouldn't get too excited its just a sample app really.

C64 Framework...

So what I'm thinking, is that I should write a very small, very simple game using the framework so that people see how you could modify it. Even if its not a complete game to be honest, just something really simeple where you run around and shoot things, or pickup things or something simple.

So no idea what I'll write... but something....simple.... This also means I'll add simple collision detection that you can butcher to do something else later.

if you have any ideas of simple games that'll not take long (and I MEAN won't take long...) let me know...

C64FrameWork: Holy smoke Batman!

I've now added the sort Dan used in Armalyte as well, so theres now 3 different modes there all available as an option for when you start your game. To select them all you need to do is change a single equate value (setting it to 0,1 or 2) and the code will build the correct version (Try doing THAT with in a monitor!).

In the case of randomly bouncing sprites Dan's clearly win's out even over my shiny new one, to the sum of 42 freely bouncing sprites all on a STOCK C64. Thats damn impressive I have to say. However, I'll emphisis that it really, Really, REALLY depends on the game and how your sprites are setup, banded, spawned, moved and all the rest - BUT with 3 separate sorts now here, you should be in good standing to pick the right one without having to mess around. The image shown here is actually the worst case (the red bar taking up top and bottom borders), normally it only takes up the lower border which is superb.

I'll also make the point that this is a frame work. Its NOT a finish bit of code. You should take this as a basic core, and shape it to target your game/applicate better. For example, if you want to have a 2 player game, you should modify the code to multiplex only 6 sprites, or if you WANT to multiplex 8 to allow for a player with multiples above and below again you should extend the code to do so.

The code is pretty well commented but due to a couple of bugs in SNASM (namely nested IF/ENDIF's dont work) I cant get the code fully auto generating yet.

I've also now added a player sprite which is controlable via the joystick and flashes away over the top of all the rest. So, barring anything else being requested (and I'll give it a couple of days) I'll write up some doc's and release it next week sometime....

Oh, and as a little aside.... when running this on a SuperCPU without even coding it in 65816 assembly, it takes up around 16 scans in total - including ALL the IRQ's....

C64 Framework progress

I'm doing pretty well with this so far and have managed to get 30 sprites being multiplexed using 7 hardware sprites. I usually prefer to leave one sprite for the player so that theres never any danger of them glitching or tearing, and also that being sprite one they will always appear over the top of the rest of the sprites. However if you wanted to multiplex all the hardware sprites, it should be pretty easy to modify things to do so. I've ended up putting both sorts in just in case theres a case where the old one wins out which may be possible in some rare instances, but mostly I expect folk to use the new one. I might also put in Dan's one from Armalyte as it has a differnt range as well and may provide yet another option given a games unique circumstanstances.

If no one gives anything else they'd really like to see added, then I'll simply add a single sprite being controlled by a joystick and that'll be it really. What's here is a good head start for any new game, as a solid multiplexor is always first on the list of things to write. Thats not to say this is the best option for every game mind. In Ballistix (and also Morpheus if memory serves), I used fixed IRQ bands and a sprite was inserted into a band the "Y" coordinate fell into. This has the added advantage that the SORT is virtualy instant as its basically a bucket sort. Take the Y coordinate, shift it down a bit, and store it at the end of the bucket list. Easy. However this multiplexor is very flexible and will allow for large joined sprites to move in sync which a fixed banded one wouldn't.

I will at somepoint do this for the Plus4 as well, but I'll need to untangle the software sprite system from XeO3 first, and that'll take time. I also don't expect people to use 30 sprites either, but its what this can manage when pushed to the limit - unless your on a super CPU of course, in which case you can use it incredibly high. I will also at somepoint release a proper SuperCPU framework but I suspect theres less demand for that since theres only a couple of folk that even HAVE one!

C64 Framework

I'm currently cleaning up my new C64 framework and just now its pretty simple. A basic multiplexor with "N" sprites multiplexed (currently 16) and rasters going and I was wondering what else I should add?

Got any ideas as to what the basic frame work should contain? It should be fairly broad scope as theres no point in specialising stuff since it would get ripped out pretty quickly by anyone actually using it, but if you can think of some common stuff you always use, like keyboard routines, joystick functions and the like... then I'll probably add them in too.

So let me know what you think would be handy....

Back to work tomorrow....

I've had a reasonably fun week or so off, but it'll be back to the usual grind tomorrow which will mean fewer updates and less playing around. Oh well, its been fun :)

I'm currently playing with lots of different things just now, flicking back and forth as the mood takes me. Currently I've got my SuperCPU hooked up as I was playing with a true dual-playfield system. Its got 2 bitmaps and masks one onto the other if you can believe it! I've said it before but Metal Dust I don't think used the power very well and does look like just a nice C64 game. To my mind the new Enforcer 2 actually looks just as good but is on a stock machine. I think you need to do something really different - something that would be impossible on a stock machine, and I'm still playing around with what that could be.

The problem with TRUE dual playfields is that you can't make best use of colour, in fact your pretty much back to 3 colour displays or you end up with huge colour clash again, and thats not very SUPER. Also to make it simpler, you really need to manually smooth scroll the front layer and that means you can't make them up from a software character map meaning you can't have it all animating away which would also be a shame. Still, I'm working away on it...

On the C64 XeO3 front I've obviously been pluggin in my new multiplexor and speeding that up, although there is one more major speed up needed here and thats when I do the sprite copy to the IRQ buffers, I also copy in the first seven sprites, however these then immediately get copied into the hardware. This means an obvious speed up is to skip that and copy the first seven sprites into the hardware directly. This will slow down the copy a little, but not having to duplicate it will be a big speedup over all - I hope.

PC Engine.... I've almost got my assembler going although I need to add a few more addressing modes to deal with TEST #??,blah types. After that I can start to play properly, however my PC Engine has started to act up and it looks like its dying, so I'll need to find my TG16 in the loft at somepoint.

Lastly... XeO3 on the Plus4... After playing Blood Money a little again, I'm starting to sway towards the player dying but the action keeps on going. You then come back on flickering or something to give you a little bit of a shield and then carry on from there. This means you won't be thrown back to the start of the level, but you WILL lose some weapon power (not all). The reason for my sudden reversal is that after playing and watching Blood Money I realise that its gonna get hard later on anyway, so even if you don't get thrown back to the start, you're not gonna finish is easily anyhow - so what the hell. It will hopefully mean most folk won't get too frustrated early on, but it does mean it'll get pretty hard later on, which was to be expected anyway I guess. I'll try this out and get a few peoples feedback, or we might even release another test although I think that unlikely for now.

Oh... and a quickie. With the C64 codebase getting pretty stable, I think I'll be releasing a framework sooner rather than later. So it won't be the full XeO3 source yet, but it will be a nice framework for starting a game in, complete with a production quality multiplexor. People can then strip it to bits and bend it into thier own idea of a framework and make some toys with it..... we can hope.

And thats where things stand for now! Fun, fun, fun!! Any questions/suggestions/gripes/feedback, please just post a comment.

NEW TOYS!!!

How cool is this!! I finally managed to get hold of a SuperCPU from ebay! Man I just LOVE ebay! (I also spend WAAAAAY too much there - oh well). So, got the super CPU, plugged it in and tried a few programs, wow does it fly! I loaded up Driller which was always painful, and now it plays like an arcade game! very cool. I also loaded up Mercenary, and its an amazing piece of work. It actually smooths out which its switched on. Doesn't just run quick, but you appear to get smoother gameplay! Looks really really cool.

I then loaded up my download program and squirted down XeO3 (which downloaded in like 1.5 seconds!) and played with switching it on/off. wow... you'd have SOOO much time to waste with one of these. I'd be tempted to write a game which uses the bitmap but blits it on and then does stuff to it that you could never do with a C64 - like 3D baddies or something. I was looking at Metal Dust, and aside from a couple of the parallax effects, you could actually get that running on a stock C64 (pretty much). But 3D baddies...Now that would be cool.

The extra RAM would also be very handy for games. I have 16Mb here, but I hear the normal is 4Mb. Even that is a huge amount. You could pre-cache and pre-rotate everything - AND run a multiplexor. Which would allow you to have all the normal hardware sprites AND loads of software ones AND possibly some 3D effects. I think Metal Dust missed the mark a little - although I'd like to have a play with it, but I refuse to pay 30Euros for it, thats just way too much for something I'd never play.

....especially as I've just gotten a Wii!!! How cool is THAT! We're all hooked on wii sports, not to mention getting heaps of excersise into the bargan. I've also been playing Crackdown (which we did at Realtime Worlds - well, I say we...but I haven't been involved in it at all), and its fab as well. I love the building jumping stuff, great fun - as are the cars and trucks. Its a much better playground than GTA ever was.

I've just recieved a stack on transisters so Im going to try hooking up my LED displays with them rather than pull-up resistors. This should allow me to use the 40xx chip I got without anything else. I discovered that the larger pic I bought REQUIRES an external clock crystal, which would bump the price up even more. We did think about having an external clock pulse and feeding that in, but it still means even more expense. So I currently think I should just use the old way and try out the PNP's I have to see if that'll do the trick.

As Im off for a couple of days, I hope to try this out soon, then I can progress with the 5 unit prototype I was making....

XeO3: Editors.

I'm taking a small break to play a bit more with my C# stuff. I've gotten the Plus/4 sprites loading in, so now all I need to do is scale them. But to see the results, I thought I'd extend the program I was doing into something a little more useful. Something that can load in sprites, characters and XeO3 style maps. I may even add editing to it at a later date.

Once I have the drawing working, I'll write a quite scale function that'll allow me to save out full size C64 sprites - although they'll be a bit rough around the edges. The biggest issue I have with XeO3 on the Plus/4, is that I can't view or edit sprites easily, Luca has to make little Plus/4 programs that show his work animating in a self contained PRG, which is far from ideal - so I hope this will help a bit more.

Level editing is also a concern as the current one was created by "FatMan", and he has long since vanished. So now we really need to be able to create one outselves, particually if we want others to make new levels or even games out of it.

I'll have to watchout when doing this program, as the temptation is to make an all singing all dancing app, which will take longer to write than the game itself. If I was doing an editor to "sell", I guess I would make everything variable and portable. But the idea is to keep the goal in mind, and not get too carried away with what should remain, a simple XeO3 editor.

XeO3: C#

So, I thought it was about time I got the full benifit of the Multiplexor, so I'm about to do a small c# program (my latest language of choice) to convert into the proper format, and scale it up to the required size. Now the aspect will obviously change, and it will look a bit naff.... but it'll help "fill" the screen with sprites AND give me a basis for converting over Luca's art in the future.

On another note, I was speaking to TNT over at Lemon64 and we got into chatting about old programming diarys from ZZap days, anyway he reminded me about the Citadel one as well as the Morpheus one I've just read. I seem to remember this one being pretty cool to. He's currently doing a supped up version of Paradroid and I'm trying to persuade him to do a diary as well. I love reading techy stuff like this, and I'm sure others do to. These days games are such a closely guarded secret that you never get to hear the gritty details which is a shape. Also things are now so complicated that it can take weeks to do the smallest thing which doesn't make for good reading.

If you have an opinion on this, or if you like reading this kind of stuff, then let me know and perhaps I'll start to try and push more people to keep retro coding blogs.