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Joe Decuir Engineering Notebook — 1977

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This is amazing history right here.

 

https://archive.org/details/JoeDecuirEngineeringNotebook1977

 

Joe Decuir's 1977 engineering notebook from when he worked at Atari, including design concepts (lots on the Atari 2600 and Atari 400/800) feasibility studies, meeting notes, teardown of competing products (such as VIC-20, TI 99/4A)

Scanned from Joe's photocopy of his notebook with his permission. At some point, Joe was made to turn the original notebook into Atari management, but he made these photocopies first. Some pages are not of the quality that we might prefer. The scans look just as good as the photocopies.
There is another notebook, from 1978, that will be scanned and posted later this summer.
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Thanks. Some interesting stuff (summary of a few things):

 

. Early reference to GTIA as "TIA2".

. Some descriptions of text/grapics modes only up to 160 pixels. References to graphics memory as 4K (maybe that's why we have the 4K LMS requirement instead of 8K).

. Page 100 "Seperate refresh cycles from object fetch cycles" (40 col text doesn't do this).

. Colleen/Candy project has reference to "Elizabeth" (a 13" colour monitor).

. Some references to 6509 (enhanced 6502 with linear memory adressing).

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Page 117 shows early RAM allocation. Up to 7 4K blocks, minimum of 8K, maximum of 28K, with upper 4K possibly dedicated to display since it's not contiguous. 4K dedicated to I/O registers. Presumably, upper half (32K) reserved for ROM as with Stella. Contrast this with preproduction memory map (36K RAM) here:

 

http://atariage.com/forums/topic/122471-atari-800-engineering-serial-26

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I am curious...Was the Notebook A4 or A5 i size?

probably neither, this was used in the US after all. Probably an "A" sheet (letter) sized notebook, or close anyway.

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The 11 x 8.5" as used in many official reference publications is almost the same as A4, as in under a quarter inch smaller each way.

 

It wouldn't make sense to have official technical scribble pads of a smaller size. When doing stuff like semi-complex circuit drawings you run out of space really quickly.

Refer the printed text on the third page. About 35 lines worth covering about half the page vertically.

Although the font is different, the size translates practically exactly when comparing to the printed OS Users Manual.

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Joe's 1978 engineering notebook is now online:

 

https://archive.org/details/JoeDecuirEngineeringNotebook1978

 

So much Atari 400/800 goodness here. This is a truly amazing trove of Atari 8-bit history that could take someone weeks to injest.

 

Here are some particularly interesting page titles, to whet your appetite:

 

Meeting w/ Grass Valley re Cassettes / Disks (p4)

Hot Idea From Jay Miner (p34)

Suggested Demo Software for Jan 79 (p35)

Possible Music Synthesizer (p43)

Liza Loop (p66)

X-Y Joysticks (p86)

Gallup Study on Personal Computers (p96)

Proposal for 'Stops Out' High Power Entertainment(?) Computer (p120)

 

-Kevin

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Omg looking at this is like seeing the Atari 8-Bits being created before you very eyes. The test program display, was that running of a prototype, maybe the first A8 screenshot ever ? looks like mixed modes.. Awesome stuff.

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Dorsett is listed on page 35. Amazing for the time that, even in the engineering stages, they were already thinking about potential software (games show up on that page too).

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The proposal for the "'Stops Out' High Power Entertainment Computer" on page 120 is the first description of what would eventually become the Amiga.

 

(Joe Decuir showed this sketch during his presentation at the Amiga 30th Anniversary celebration at the Computer History Museum last year).

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So the atari 400 and 800 Came out first. Was the Atari 800 Sold with 16k in the beginning ? As a ugradable computer to 48K . Was thinking about the 5 colors in the playfield and the 4 single color players and missile design, Wonder if that has something to do with memory, i mean if you could have picture with 16 or more colors at the same time wouldnt that need more memory both screen memory and for the Image data itself. But back in the late 70's 16K was actually seen as a large memory and so the design around the Atari Graphics colors and player missiles had to be in conjuction with what would be a reasonable memory usage and give a reasonble result at the time ?

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i know about different graphics modes of the Atari. and i know about the DLI so the Atari can show many more colors using different tricks and also the players becomes multicolor when overlapped. The above question is about one of the most common graphics modes, Or the out of the box cababilities that it was meant to have when the Atari 8-Bits where realeased to the public.

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Supposedly the initial plan was for 4K (400) and 8K (800) which was used to give the computers their names.

 

By the time the machines came out, Ram had dropped in price enough such that 8K and 16K became the standard for each.

The original OS does memory detection in 4K blocks even though no standard memory expansion was anything other than a multiple of 8K.

 

4K would make for a fairly crippled system. Even with 8K you can't run a fullscreen hires mode and also have the OS maintaining it's 1/2K worth of work memory.

Some early games on cartridge were designed to work with 8K Ram. Star Raiders and Asteroids are two of them.

 

# of colours and available memory don't necessarily correlate. You can put lots of colours onscreen and not necessarily use much memory.

But generally you don't get a fullscreen picture at hires in under 8K. 7,680 bytes for a 40 byte * 192 scanline screen then about another 200 for the Display List = ~ 7,880 which is only about 300 short of 8K.

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If you're in charmode on a [40x24]chars screen that is 960Bytes, less than 1KB. If we had a colourmap than each char could have each own colour.

On our similar to C64 Antic4/GR.12 where we have only two own colours (PF2 and PF3) we could had many more PFs registers had they build the machine with them. I don't see this related to memory but more PMGs yes as ours takes 1,25KB. screen memory reserve and *more is *memory more to be used.

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So then the design around the colors and player missiles maybe had a little bit with memory but also they wanted to produce a machine at a reasonble cost and features that where considered very good in the late 70,s. So they probably used the Atari 2600 arcitecture as a example and improved upon that. The Atari 2600 used lots of tricks i guess to create all the colors on screen, So my guess is the The Atari 400/800 was design with that in mind, Using DLI's and special tricks to produce many colors and or many moving objects, sprite multiplexing and so on. Well it seems so. In the late 70's these machines where very advanced for its time, well it seems so too me.

Edited by Grevle

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Glancing at this there's definitely some interesting stuff....

 

Like the fact that they planned for the 400 to be more like the XEGS w/ an external keyboard as an add-on option. Strange that they wanted to use 2 joystick ports instead of a dedicated keyboard port though. Design notes for a cheap "slow floppy" running at 35rpm were interesting too.

 

The user surveys showing gaming not being a big seller were also kind of entertaining.

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Like the fact that they planned for the 400 to be more like the XEGS w/ an external keyboard as an add-on option.

 

Can't remember where I heard it (might have been Joe Decuir's interview for Antic podcast) but Star Raiders, and its dependency on keyboard commands, is the reason the 400 has a built-in keyboard.

Edited by FifthPlayer
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