Jump to content
IGNORED

My Personal Pie-In-The-Sky Project, Based on the ASG Documents from the Atari History Museum.


Ben Breeck

Recommended Posts

Once upon a time, starting around 1980, the Atari Semiconductor Group, the advanced R&D arm of an Atari then under control of Warner Bros. began brainstorming and then developing computer chipsets for the follow-up, if not not the linear backward-compatible successor to the Atari 8-bit series, as well as provide the hardware platform for Atari's Coin-Op division for years to come.  While the original plan was to use the Motorola 68000 as the main CPU, the original chipset was designed and engineered to be CPU agnostic, in case new and better CPU instruction sets and cropped up between the beginning of the project and its fruition.  Then Jack Tramiel bought Atari, and threw out all that work in favor of the project created by his own pet engineer Shiraz Shivji, creator of the Commodore VIC-20 and 64, the Atari ST.  The engineers working on what had been Projects RAINBOW/SIERRA and OMNI scattered to the four winds, ending up in places such as Hewlett=Packard, Digital Equipment, Silicon Graphics, and Sharp (which would release the X68000 three years later)!  Twenty years later, Curt Vendel, of the Website Atari History Museum would begin collecting notes and data surrounding those projects from primary sources and publishing them on his website.

 

There have been several retro-computing efforts in recent years based on the products of Commodore and Apple (A non-exhaustive list would include not just the Commander X16, but also the C256 Foenix, the MEGA65, {better followups to the 64 than the 128}, the Apollo Vampire {Amiga AGA followup that should have been but never was}, and the Replica 1 {Apple I Recreation}.).  I think it's high time that Atari-based victims of thwarted destiny got in on the action.

 

At the moment, these notes constitute a what-if fantasy, that I am trying to bring to the level of plausibility in order to (one day) turn into a salable product, if I ever strike it rich or can at least (legally) raise sufficient capital.  The only truly non-negotiable components are graphics chips themselves and their necessary Video RAM.  Everything else: the CPU (within certain limits), the supporting sound chips#, I/O controllers, the OS and IDE/APIs, and even the form factors themselves are (at the moment) are all up for grabs.

 

The original .pdf copies of these documents came from the Atari History Museum website.  Unfortunately, Curt Vendel, the maintainer of that site, passed away around twenty-one months ago of undisclosed causes., meaning that, in all likelihood, no more notes on the Projects RAINBOW and OMNI chipsets will ever see the light of day.  The website’s news page still works, but that’s because it’s a mirror on Facebook.  The Atari History Museum stopped working last September, exactly why has not been stated even on that aforementioned Facebook page.  The copies of these documents I obtained are the from latest available mirrors I could find from the Internet Wayback Machine.

 

I am going to reserve specific posts at the beginning of this thread so that I can fill in details of this project on the first page at my (relative) leisure.  While I do plan to add a poll at some point to this thread, not all of my questions for this project will go up on it; the questions that don’t are questions of (estimated) fact, not solicitations of opinion.

 

I chose this name for my project because the "Hibana" is the other Japanese pronunciation of the kanji meaning "Atari" in the term "Sekka no Atari," and because Spectrum, Rainbow,  and Prism have already been taken as product names for computer hardware, "Main Sequence" being a reference to the Main Sequence of the Hertzsprung-Russel Diagram

 

Notes:

#:  If it turns out that AMY is simply too difficult or too expensive to offer proper implementation for, I have a “Plan B,” but that can wait until we get to the sound chip post for me to fully explain.

 

P.S., I've tried to ask the mods about the most appropriate place for this thread, but I haven't gotten a response.  If there's a better, more appropriate place for this thread, then I ask the mods to place it there, notify me, and give me any appropriate demerits, as the situation demands. 

Edited by Ben Breeck
Improving readability
  • Like 3
Link to comment
Share on other sites

Moving on...

 

Obviously, the graphics chips are the stars of the show.  I plan to use HEATHER as the basis of my primary display adaptor.  I chose HEATHER from OMNI over GOLD from RAINBOW for four main reasons:

 

1: GOLD lacks an actual color generation scheme (that's on another chip, whose notes are unavailable).

 

2: GOLD can only address 1 MB of Video RAM, while HEATHER can address 16 MB.

 

3: HEATHER includes all the bus signals of GOLD, in addition to signals all its own.

 

4: VIVIAN includes DRAM Refresh Hardware.

 

That said, I am toying with going with a different color generation scheme:  The complex color generation method that only generates 2304 possible colors makes little sense when something like the Commander X16 can manage 4096.  I am towing with either a 16-bit or 24-bit color method, for reasons involving my indecision involving the CPU and Support Chips.  The 160bit scheme would involve two 15-bit schemes, selectable between the two with the top bit.  The first scheme would be five bits each of RGB, while the second scheme would be three bits each of magenta, yellow, cyan, negative luma, and alpha/translucency.  The 24-bit scheme would be eight bits each of RGB.

 

I plan to feature at least three resolution modes (288x224, 576x448, 816x632) in a 7:9 aspect ratio.  This is a classic arcade ratio used by the likes of Namco, Sega, Taito, and Irem.  It also allows for fairly eaven Video RAM calculations, and I can manage a full 24 bit chunky pixel bitmap on the highest resolution for only 1.5 MB.  As an extra bonus, these resolutions minimize interpolation problems.

 

In terms of graphical assets, I would like at least 32 SILVER object generators and 96 PENNY sprite engines.  The questions become,  how many LUTs and other FPGA assets do these features consume each, and how much Video RAM is needed to make use of them.  The answer to the latter for SILVER object generators is fairly straightforward:  In the original spec, they were, at 8-bit color depth per pixel, 1/8 the screen width and the whole screen height, which at that color depth equals 31.5K@576x448 resolution, so double or triple that at higher bit depths.  PENNY sprites, however, are rather more variable in function and size, though each, according to the original spec, has 83 possible frames of motion.

 

 

Display_Functionality.pdf OMNI-Memo_OCT-20-1983.pdf PENNY_SCHEMATIC..pdf PENNY-OCT83.pdf PENNY-Semiconductor_Info.pdf PLAN_January-23-1984.pdf Programming_Vivian.pdf Rainbow_Gold_Chip-Specifications-28OCT83.pdf Rainbow_Silver_Chip-Specifications-23JAN84.pdf SPEC_January-13-1984.pdf THEORY_March-9-1984.pdf VIVIAN_SPECS-January-16-1984.pdf VIVIAN-Semiconductor-Info_January-8-1984.pdf DETAILS.HEA.pdf

Edited by Ben Breeck
Oops
Link to comment
Share on other sites

For the sound system, I am planning on employing a Sound CPU with a grand total of 1MB of sound RAM, driving four specific sound elements:

 

1: a POKEY variant, specifically a QuadPOKEY, specifically, a POKEYMax 3.x.

 

2: AMY, unless creating an FPGA Core is too much trouble, in which case Plan B is to use the Dream SAM2695, which may force me to use a microcontroller with an extra DMA to handle its internal RAM buffer and instrument ROM.  It's a subtractive MIDI synthesizer developed by reverse engineering the Roland MT-32's sound generator, so it's just as theoretically "mathy" as AMY, just in the opposite direction.  Yes, 64 channels is blatant overkill, but Dream discontinued the 32 and 16 channel versions a while back.

 

3: A mid-late eighties Yamaha FM sound chip and (if necessary) matching DAC, or some second-source version from Casio, Alumer, or Phillips.  I'm leaning towards the YM2414, whose tone I fell in love with on Youtube.  It is an eight channel, four operator chip with eight possible wave forms.  If I cannot find enough new old stock, I'd be willing to settle for a WM2151 or WM3812, the latter best known as the sound chip used in the original Roland Ad-Lib and Creative SoundBlaster sound cards.

 

4: Some wavetable and/or PCM sound chip.  I'm leaning toward the Seta X1-010, because of its flexibility and the way it's already been integrated into the MISTer FPGA project, but I'm also looking at the Ensoniq ESS55 series (used in things like the Apple IIgs, the Advanced Gravis WaveMaster sound card, and several Ensoniq keyboards), the original SegaPCM, or one of the Ricoh RF5C series.

 

AMY is an additive synthesizer using either 64 or 128 oscillators (depending on application/configuration) and a 16K control ROM.  This is all the text I can find from the Atari History Museum.  The rest of the files were .zip files of things like music samples and a digitized tape out of a preliminary (and presumably still buggy) version  in a format no longer supported by industry standards.

 

The real question is: Does AMY absolutely demand using an FPAA?  If not, how many FPGA gates would be needed for a digital version, and how many LUTs would that translate to with the FPGA in the DE-10 Nano?  And naturally, if I don't like the answer, I can always go with Plan B.

 

AMY_development_notes.pdf

AMY_1_spec_confidential_binder_ver_2.pdf AMY_chip2_notes.pdf AMY_formulas.pdf AMY_general_description.pdf AMY_tech_manual.pdf AMY_development_notes.pdf

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...
  • Recently Browsing   0 members

    • No registered users viewing this page.
×
×
  • Create New...