(My) Interview with John Croudy (A8 Druid).

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(My) Interview with John Croudy (A8 Druid).

Postby lostdragon » Mon Dec 08, 2014 8:19 pm

http://www.grumpyoldgamers.co.uk/index. ... interview/

Been trying to track John down for AGES...fantastic answers and IF he can get his hands on the original designers notes he worked from, he's going to scan them and send them over to me.Most kind indeed.

Enjoy the interview.

:-)

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Re: (My) Interview with John Croudy (A8 Druid).

Postby lotek_style » Wed Dec 10, 2014 6:58 pm

Thanks a lot! Really loved Druid on the 8bit... I even took my first nickname from the game :)
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Re: (My) Interview with John Croudy (A8 Druid).

Postby Cyprian » Wed Dec 10, 2014 9:55 pm

Actually, the ST did have a blitter but it was shockingly slow. It took so
long to set it up for one blit that it was simply quicker to use the CPU to
do the blitting. So the blitter went unused in all our games


interesting point of view..
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Re: (My) Interview with John Croudy (A8 Druid).

Postby Frank B » Wed Dec 10, 2014 10:36 pm

More slower than the cpu nonsense. Set up time isn't any more complex than the amiga. Perhaps he was accessing it via the operating system or via the very general purpose Atari sample code.

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Last edited by Frank B on Thu Dec 11, 2014 8:28 am, edited 1 time in total.

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Re: (My) Interview with John Croudy (A8 Druid).

Postby Frank B » Wed Dec 10, 2014 10:39 pm

Looks like he doesn't like the ST :)

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Re: (My) Interview with John Croudy (A8 Druid).

Postby lostdragon » Mon Dec 22, 2014 8:22 pm

John's views are of course his own personal ones and based on his experience working on the hardware itself.

Anything that encourages debate i personally welcome with these interviews, I.D's Dave Taylor's had a similar reaction amongst the Atari community. :-)


My 'plans' for interviews in 2015 are to tread a different path, as along with the 3 interviews which will appear in ST Gamer Vol 2, i'm now supplying interviews for 2 'publications' along side ST Gamer.

1 another Digital Only affair, the other a physical print magazine.More details once the 1st interviews go 'live' in said magazines.

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Re: (My) Interview with John Croudy (A8 Druid).

Postby croudyj » Mon Dec 22, 2014 10:04 pm

Hello everyone,

I just thought I'd respond to the comments about my attitude towards the ST and its blitter. First, I'd like to mention that the operating system was never involved in any of my games on the 8 or 16 bit Ataris. The first few lines of code in the game switched the OS off and took over the whole machine. It was too slow to do it any other way.

When I write about this stuff, I'm just writing it as I remember it. I'll admit that my memory is very faded and sometimes plays tricks on me. I'm talking about 1987-1990 which is so long ago it feels like another lifetime. What I do remember about the ST's blitter was that I couldn't figure it out on my own and got Ronald Pieket to help me. I don't remember how we approached it, but it's very possible that we did something wrong. All I remember was that we looked at each other in horror when we saw the results of using the blitter. I think the results were ever so slightly faster than the CPU, but not enough to make it worth bothering with. Like I said, we may have done something wrong. If the blitter was better than I thought, it's a real shame I didn't know how to use it.

You're right, I don't like the ST, but on thinking about that I realise that it's not really the machine's fault. Programming at that time could be very frustrating because it was so difficult to get information. Since there was no Internet, I was at the mercy of any books I could find. I only had a few ST books and they were very bad. One was an awful translation from German and written by a guy who clearly didn't understand the 68000 very well. If I couldn't figure it out, or find anyone who knew the answer, all was lost. It's this frustration that has coloured my memory and feelings towards the machine in a negative way. I don't have those bad feelings towards the Atari 8-bits or the Amiga because I was able to get my hands on excellent documentation for both.

John

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Re: (My) Interview with John Croudy (A8 Druid).

Postby Frank B » Tue Dec 23, 2014 1:06 am

croudyj wrote:Hello everyone,

I just thought I'd respond to the comments about my attitude towards the ST and its blitter. First, I'd like to mention that the operating system was never involved in any of my games on the 8 or 16 bit Ataris. The first few lines of code in the game switched the OS off and took over the whole machine. It was too slow to do it any other way.

When I write about this stuff, I'm just writing it as I remember it. I'll admit that my memory is very faded and sometimes plays tricks on me. I'm talking about 1987-1990 which is so long ago it feels like another lifetime. What I do remember about the ST's blitter was that I couldn't figure it out on my own and got Ronald Pieket to help me. I don't remember how we approached it, but it's very possible that we did something wrong. All I remember was that we looked at each other in horror when we saw the results of using the blitter. I think the results were ever so slightly faster than the CPU, but not enough to make it worth bothering with. Like I said, we may have done something wrong. If the blitter was better than I thought, it's a real shame I didn't know how to use it.

You're right, I don't like the ST, but on thinking about that I realise that it's not really the machine's fault. Programming at that time could be very frustrating because it was so difficult to get information. Since there was no Internet, I was at the mercy of any books I could find. I only had a few ST books and they were very bad. One was an awful translation from German and written by a guy who clearly didn't understand the 68000 very well. If I couldn't figure it out, or find anyone who knew the answer, all was lost. It's this frustration that has coloured my memory and feelings towards the machine in a negative way. I don't have those bad feelings towards the Atari 8-bits or the Amiga because I was able to get my hands on excellent documentation for both.

John


I approached the ST one after getting to grips with the Amigas. That helped. It took me about a day to get a general purpose sprite routine written. I was 16 at the time. The concepts are more or less the same as the Amiga. If anything the Amiga is slightly more complex. If you used "documentation" like the blitter section in ST Internals I'm not surprised you were confused! Atari published a blitter manual which was fairly good. It included some very general purpose sample code which is too heavy weight for games. Excluding set up time it takes 6 bus cycles (24 cpu cycles) to mask and shift a 16 bit word on the screen. Excluding setup time you're not going to beat that on the CPU. It's fast enough to throw a 320*200 4 plane screen around on a pixel boundary in a pal frame with VBL time left. Try that on a 68k ;)

If you're curious the manual is here http://dev-docs.atariforge.org/files/BL ... 7-1987.pdf

It's also capable of brush magnification and hflipping a raster image in 4 passes. Very elegant design.
I had the ST blitter drawing 30 32*32 2 plane objects including clearing in a frame. The setup time was negligible. Good luck trying that on the CPU without pre shifting :)
It's criminal that it wasn't more widely used.

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Re: (My) Interview with John Croudy (A8 Druid).

Postby croudyj » Tue Dec 23, 2014 2:59 am

I'm devastated! My apologies for letting the Atari community down. I had no idea that my games could have been so much faster. Looks like I really messed up there. Perhaps I should have made more effort to get proper docs. On that day when I decided the blitter wasn't worth the trouble, I did wonder why on earth they would have designed it so badly. Now I wish I had looked into it further.

All I remember now is the frustration I felt. I used to call up book shops to try and see if they had something in stock that I could use. I usually ended up browsing the shelves desperately looking for something. I remember the day I heard about the 8-bit book "De Re Atari". It was only by chance I saw it in the window of a computer shop. I jumped on it. It was £25 just for the unbound sheets of paper. That was pretty expensive for a book in 1982 but I had to have it. Without that book I would never have been able to do anything good on the 8-bit machines. Prior to that I had been relying on gems from magazine articles!

Well... I'm truly sorry. What a fail :(

John

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Re: (My) Interview with John Croudy (A8 Druid).

Postby Frank B » Tue Dec 23, 2014 11:43 am

croudyj wrote:I'm devastated! My apologies for letting the Atari community down. I had no idea that my games could have been so much faster. Looks like I really messed up there. Perhaps I should have made more effort to get proper docs. On that day when I decided the blitter wasn't worth the trouble, I did wonder why on earth they would have designed it so badly. Now I wish I had looked into it further.

All I remember now is the frustration I felt. I used to call up book shops to try and see if they had something in stock that I could use. I usually ended up browsing the shelves desperately looking for something. I remember the day I heard about the 8-bit book "De Re Atari". It was only by chance I saw it in the window of a computer shop. I jumped on it. It was £25 just for the unbound sheets of paper. That was pretty expensive for a book in 1982 but I had to have it. Without that book I would never have been able to do anything good on the 8-bit machines. Prior to that I had been relying on gems from magazine articles!

Well... I'm truly sorry. What a fail :(

John


I wouldn't worry about it :) It was 20 odd years ago. I suspect the real culprit was Atari's lack of documentation :)
The Amiga documentation was very good. The hardware reference manual was impressive. It was concise, detailed and totally accessible even for novice programmers.
Do you have any source you could gift the community? Might be fun to do some remixes of old games :)
Last edited by Frank B on Tue Dec 23, 2014 11:57 am, edited 1 time in total.

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Re: (My) Interview with John Croudy (A8 Druid).

Postby Frank B » Tue Dec 23, 2014 11:48 am

lostdragon wrote:John's views are of course his own personal ones and based on his experience working on the hardware itself.

Anything that encourages debate i personally welcome with these interviews, I.D's Dave Taylor's had a similar reaction amongst the Atari community. :-)


My 'plans' for interviews in 2015 are to tread a different path, as along with the 3 interviews which will appear in ST Gamer Vol 2, i'm now supplying interviews for 2 'publications' along side ST Gamer.

1 another Digital Only affair, the other a physical print magazine.More details once the 1st interviews go 'live' in said magazines.


Indeed. I enjoyed the interview :)

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Re: (My) Interview with John Croudy (A8 Druid).

Postby lotek_style » Tue Dec 23, 2014 5:27 pm

Wow it's John Croudy :) Welcome to the board and... Druid 2: Enlightenment port please ;)
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Re: (My) Interview with John Croudy (A8 Druid).

Postby croudyj » Tue Dec 23, 2014 8:40 pm

Thanks guys. I got pretty depressed last night mulling over that blasted blitter :oops:

Anyway, I don't have anything left of the ST. No machine, no disks, no printouts. As for the Atari 800, my sister, until recently, had all my equipment and disks, but she sold the lot on eBay about a year ago. However, she has just posted something to me from 8-bit Druid, some sort of design notes. I should be able to share that with you when it arrives.

:cheers:

John

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Re: (My) Interview with John Croudy (A8 Druid).

Postby Frank B » Thu Dec 25, 2014 3:06 pm

There are lots of good emulators for both platforms :)

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Re: (My) Interview with John Croudy (A8 Druid).

Postby Stefan jL » Thu Dec 25, 2014 6:36 pm

With or without blitter i consider Ninja Warriors, Silkworm and ST Dragon very well made ST games :)

John did you work on the ST version of Swiv also?
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Re: (My) Interview with John Croudy (A8 Druid).

Postby Frank B » Thu Dec 25, 2014 11:00 pm

Swiv was a superb game
St dragon was also very good.

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Re: (My) Interview with John Croudy (A8 Druid).

Postby croudyj » Mon Dec 29, 2014 1:57 am

Thanks :) No, I didn't work on the ST version of SWIV. I think by that time I was working on Indy Heat for the Amiga. I did write the end-of-game reactor explosion sequence for SWIV. I think the same code may have been used in both versions.

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Re: (My) Interview with John Croudy (A8 Druid).

Postby dma » Mon Dec 29, 2014 8:29 am

Hi John,

Thanks for your work on those games conversions, it seems i played to all those you took part in.
Especially Silkworm, with its great and indeed arcade faithful gameplay.

Also someone who built a homemade analog synth is automatically a great person. ;)

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Re: (My) Interview with John Croudy (A8 Druid).

Postby lotek_style » Mon Dec 29, 2014 5:40 pm

John: I wonder... there are a couple of chipmusics in the ASMA Atari 8bit music archive... they are credited to you with a questionmark... can you confirm that you did these musics too?

Asteroidz and Munching Mandy
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Re: (My) Interview with John Croudy (A8 Druid).

Postby croudyj » Mon Dec 29, 2014 6:37 pm

dma wrote:Thanks for your work on those games conversions, it seems i played to all those you took part in.
Especially Silkworm, with its great and indeed arcade faithful gameplay.
Also someone who built a homemade analog synth is automatically a great person. ;)


Ha ha -- a crazy person more like. Thanks for the compliments :lol:

John

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Re: (My) Interview with John Croudy (A8 Druid).

Postby croudyj » Mon Dec 29, 2014 6:49 pm

lotek_style wrote:John: I wonder... there are a couple of chipmusics in the ASMA Atari 8bit music archive... they are credited to you with a questionmark... can you confirm that you did these musics too?
Asteroidz and Munching Mandy


Oh my God! Those were private projects that I did at home in 1983-1984 before I had a job doing games. They were sold on eBay by my sister. Seems like the guy who bought my stuff knew what to do with them. EDIT (25.4.2015): I originally said here that the guy didn't ask for permission first -- but he did and I had forgotten. He emailed me the following "I would like to proudly present your lost/forgotten games for the community." I just didn't realize that meant he would put the games on the net - DOH! I'm glad he did, I got to see screen shots I thought I would never see again. The games are here: http://gury.atari8.info/news_2013.php - My apologies to this fine chap who preserved my work.

So, yes. I did those. 'Munching Mandy' was a Pac Man like game. The tune is from a song I recorded in 1982 in my 'home studio' (i.e., bedroom).

'Asteroidz' was a copy of the arcade machine 'Asteroids'. I made a custom control board and used it to learn how to play at home so that I could go to the arcade and play the real machine like an 'expert'. The music was a pretty bad rip-off of that classical piece from 2001 - A Space Odyssey.

Could you give me a link so I can check these out?

Thanks.

John
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Re: (My) Interview with John Croudy (A8 Druid).

Postby lotek_style » Mon Dec 29, 2014 7:57 pm

Well the musics can be found here:

http://asma.atari.org/

I haven't found a dl link for the games.
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Re: (My) Interview with John Croudy (A8 Druid).

Postby croudyj » Tue Dec 30, 2014 6:58 pm

Thanks. It was nice to hear those again. I wouldn't mind if the games themselves got released too. I never thought any of that would ever be seen by anyone except me and my friends.

John

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Re: (My) Interview with John Croudy (A8 Druid).

Postby leonard » Tue Jan 13, 2015 3:43 pm

Frank B wrote:Excluding set up time it takes 6 bus cycles (24 cpu cycles) to mask and shift a 16 bit word on the screen


Hi,

Could you elaborate on this? I'm not a blitter expert but it seems quite fast. If it takes 6 bus cycles for 1 bitplan, 16 pixels, it takes 24 for 4 bitplans. A complete 4 bitplan screen is 20*200*24 = 96000 bus cycles, which means more than twice a PAL 50Hz frame. (PAL frame is 313*128=40064 bus cycles). Did I miss something?

On the other hand, when you say "mask", you mean a generic mask pattern (read from memory?) (and not the two end masks that you can't setup for each line of the sprite?).

cheers
Leonard/OXYGENE.

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Re: (My) Interview with John Croudy (A8 Druid).

Postby Frank B » Tue Jan 13, 2015 5:38 pm

leonard wrote:
Frank B wrote:Excluding set up time it takes 6 bus cycles (24 cpu cycles) to mask and shift a 16 bit word on the screen


Hi,

Could you elaborate on this? I'm not a blitter expert but it seems quite fast. If it takes 6 bus cycles for 1 bitplan, 16 pixels, it takes 24 for 4 bitplans. A complete 4 bitplan screen is 20*200*24 = 96000 bus cycles, which means more than twice a PAL 50Hz frame. (PAL frame is 313*128=40064 bus cycles). Did I miss something?

On the other hand, when you say "mask", you mean a generic mask pattern (read from memory?) (and not the two end masks that you can't setup for each line of the sprite?).

cheers


Hi Leonard.

Copying a 16 bit value takes two bus cycles (8 cpu cycles). It's a R/W operation
Masking a 16 bit value takes
1 AND pass (R/M/W) which is 3 bus cycles or 12 CPU cycles*
1 OR pass ((R/M/W) which is 3 bus cycles or 12 CPU cycles*

When I say 16 bit value I mean for one plane. You can mask about 1/3rd of the screen in four planes.
You can copy approx 5 planes** in a PAL frame. You could clear about 10 in a frame on an ST* (80,000 bytes)

Shifting is totally free.

HTH. The blitter has three speeds. 1 bus cycle (Write), 2 bus cycles for copy (read/write) and 3 for a read/modify/write where bits in the destination need to be preserved. This excludes bus sharing mode. You can drop 10% off the throughput for the restart method.


So to recap. When it comes to blitter rendered sprites:

1) No need to pre shift anything, Shifting is free. Massive RAM savings of potentially 15x for every sprite.
2) No need to waste memory on an extra "shift into column". 32 pixel wide sprites are 2 words wide per plane not 3. Memory saving of 33%
3) "" for the mask. 33% memory saving of one column too!
4) No need to unroll all your sprite code. Memory saving there.
5) No need to double up your mask data into 2 planes to hit memory 32 bits at a time. One plane is fine.
6) Brute force masking is faster than a preshifted algorithm which does a read -> (read modify write * planes) with the CPU

It's amazing it wasn't used more.

Downsides: You need to be careful with CPU interrupt latency

Caveats:
*This isn't the case for the shift into word at the end if the source is aligned. Eg if the sprite is 32 pixels wide it'll be 48 with the shift word.
The blitter can omit the last source read. The last column is drawn faster.

**Yes there are only 4 ;)


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