Raven. A homemade Atari-like computer

[agranlund]

Some time ago I made a small and very basic 68000 computer.
Simple as it was, that whole process was incredibly satisfying and it lead me to start putting together a design of something that would be more like a real and usable computer.

I call it Raven.
It's not nearly as posh as that other bird from Atari :)

More details can be found on Github: https://github.com/agranlund/raven

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It's still in bring-up phase but this first prototype has shown enough promise that I think it deserves a build blog.
There will eventually be a second/final revision based off notes I'm collecting from getting everything on this one tested.

This is the status of the machine as of today:



The specs of prototype A0:
68060 CPU, 48MB RAM (max), 16MB ROM (max)
High speed serial, Legacy serial, Legacy parallel
YM2149 sound, Battery backed clock
Eiffel for keyboard+mouse+joysticks
Audio in/out, Midi in/out (TRS Type-A)
4x ISA expansion (16bit)

It's never intended to be a 100% hw compatible computer - just enough to run the OS friendly stuff.
There's YM and MFP onboard mapped to the normal Atari locations which helps of course.
Longer term, I'd like to explore using my CaSTaway port for running ST games on it by help of (partial) software emulation.

But really, the main goal is just to have fun making my own computer.
I'm basically treating this as a one-off for me, though all the stuff will go to Github once it's past prototyping if someone else wants to build one.
(This probably reflects on the design. I'm sure if someone where to make some kind of product meant to compete with existing stuff they would make different design decisions)

[agranlund]

And some older pictures of, for me, quite exciting stages :)

Kicad

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Boards arrive and test fitting in the intended home:

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Verifying reset and power-on stuff:

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Some different RAM+ROM modules and the ROM programmer:

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Freerunning the CPU

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Beginning of bios and first text output from the computer

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EmuTOS over serial connection

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[exxos]

:bravo: :2k2:

It's almost like the Milan 060 which never was :)

[mrbombermillzy]

My goodness! This is amazing! :dizzy:

[rubber_jonnie]

WOW!!!

:dizzy:

[chronicthehedgehog]

:2k2:

[atari030]

Wow. Its a work of art.

[HigashiJun]

Well done !

Can we expect an official release soon ?

:D

[Badwolf]

ROM SIMMS? You're a madman! :lol:

I love it. Great work.

BW

[agranlund]

ROM SIMMS? You're a madman! :lol:

I love it. Great work.

BW

That, and deciding to go with custom RAM Simms, greatly simplified routing on the mainboard
(though routing this thing was still by far what took the longest)
Also, I just think it looks awesome with those custom simms in matching color...

All the Simm slots have exactly the same pinout and each have 16MB physical address space for simplicity.
The boot bios enumerates what's actually installed and maps it to linear ST-RAM, TT-RAM and OS-ROM in the usual Atari location.
It does a bit of other setup too and then jumps to $E00000

Same for the YM and MFP. Their physical addresses are actually not in Atari locations but placed such that the boot bios can easily map them there on startup.
This greatly simplifies the physical address decoding, and more importantly the amount of address signals needed to be routed to the ATF1508.

It's all in the spirit of "go with what's easiest for Granlund" :)