Raven. A homemade Atari-like computer

[frank.lukas]

ISA are 16bit and the Atari single VME Bus are 16bit too. VME is a 68k Bus ...

[agranlund]

What about to Desgin a ISA to VME Interface to use a ATW800/2 ...?

That would be neat, I'd buy it :)

[agranlund]

It doesn't happen too often but I sat down to have fun with KiCad.
I see traces everywhere now :)

a2wip_250712.png

I stumbled upon a flaw with the realtime clock on the current board.
It'll go to battery backup mode when the power is turned off, as opposed to when the power plug is disconnected, draining the battery when it doesn't have to.

Has been fixed for rev.A2 but there's no super-easy way to patch it on current revisions.
(you'd want pin8 of U406 to receive +5VL standby power from the ATX power connector instead of the regular +5V)

[PhilC]

Hinting, remember there's plenty of room to move the 68150 to make soldering the buffers easier.

Were you going to add a network chip this time?

[agranlund]

Were you going to add a network chip this time?

Yes, it currently has one and I removed the PS/2 port in favour of a stacked USB + Ethernet port.

Screenshot 2025-07-12 at 17.21.20.png

All in all it's only a small and final(??) iterative update on the Ax revision.

So far, and subject to changes-on-a-whim as usual :)

Code: Select all

Silkscreen: Fixed wrong pinout info for J305
Silkscreen: Reversed order of RAM simms
Silkscreen: Clearer orientation for a bunch of headers
Silkscreen: Clearer pin1 markers for a bunch of SMD footprints
Footprint: Larger footprints for handsolder D201, D202, D203
BOM: Replaced PLCC64 socket for U104 with black part
BOM: Replaced PLCC84 socket for U108 with black part
BOM: Replaced buttons SW101,SW201,SW202 with black parts
BOM: Changed C310 to 0.1uF (was 0.01uF)
Replaced through-hole DS1818 with DS1818R (SMD version)
Fixed RTC power delivery, now using ATX standby power
Added small solderpad for securing Y402 to board
Added 68150:BUSCS signal separate from 68150:CS
Added pullups on 68150 data bus
Added pulldown on IDE:IRQ
Added i2c eprom with preprogrammed MAC address
Added i2c expansion header
Added internal USB header (two ports)
Added W5100s ethernet controller
Replaced Eiffel with CKBD
Replaced 2xPS2 connector with 2xUSB + Ethernet
CPU temperature sensor to CKBD
PowerOff control from CKBD
PowerSwitch status can be read through XR68M752 (detect powerbutton held down during boot)
Replaced one 12V fan header with PWM + ARGB
Changed IDE interface to big endian as standard on Atari machines

[PhilC]

Nice update. Are you planning to build one?

[exxos]

It doesn't happen too often but I sat down to have fun with KiCad.
I see traces everywhere now :)

Looks good :) Someone has a lot of patience :P

[agranlund]

Nice update. Are you planning to build one?

Oh yes, but I'm not fully sure when yet.
I'm going to let it simmer for a bit to see if I want to add or change anything.

[Mikerochip]

Going to build a rework list too, for the A1 boards?
Or, well. Should we create one?

If we added an "official" rework in this section or maybe the user builds section of the forum?

What made me think of it is the TT official rework schematics :P


Also, would it be easy to add in actual sockets for the 68901 etc, to the schematic?
That way we can have both the parts on the BOM, and the scocket part in the pcb.
I presume it's a chunk of extra work, for not really a lot of gain, apart from making the iBOM complete :P

[agranlund]

Going to build a rework list too, for the A1 boards?
Or, well. Should we create one?

There's not much or anything(?) that really needs reworking but I agree it would be nice with a better and more organised page that describes how to make the A1 a bit more like A2.

- Some kind of patch for the RTC power delivery is perhaps the closest one that fits the bill.
- The small fix on the current revision of the CKBD upgrade board if one is interested in the fan control.
(a new version of that PCB is currently on the way here and I'll update Github once I've built and verified it)
- IDE interrupt is not working on rev.A1 and it should be an easy patch, but nothing(*) is using it so it's not a big loss.
(*) if someone decides to port AtariTOS then it could be useful. MagiC normally does too but the Raven port does not.

CKBD is pretty much plug-and-play but some patch wires can be done for additional but non-essential features.
https://github.com/agranlund/raven/tree ... rades/ckbd

IDESwap is completely plug-and-play but also super optional and not essential unless MagiC or perhaps a theoretical port of Atari TOS.
https://github.com/agranlund/raven/tree ... es/ideswap

And as I typed all that I realise that yes, it's a great idea if this was properly documented :)

Also, would it be easy to add in actual sockets for the 68901 etc, to the schematic?
That way we can have both the parts on the BOM, and the scocket part in the pcb.
I presume it's a chunk of extra work, for not really a lot of gain, apart from making the iBOM complete :P

They already are, both in the schematic and in the bom :)
https://github.com/agranlund/raven/blob ... -a1_bom.md

But I see that I had it show only the IC's in the iBOM. I don't remember the exact reason for that but perhaps I thought it was redundant with both there. Or maybe I made a mistake.