SE/30 Combined Ethernet/Video PDS card

[MacDoctorFL]

Would it be possible to make a PDS slot card to hold a R-Pi or other SBC to act as an ethernet adaptor and video out. Power requirements would be low. Just a thought. Any takers?

This is my first post. Hello World! and fellow 68k-ers.

 

[tact]

Welcome newcomer. That would be quite a big project to interface the pds slot with a pi to use as an ethernet and video out adapter and also make the drivers for the mac itself.

 

[Trash80toHP_Mini]

Welcome aboard! Very nteresting first post you've made here.

Dunno about the R-Pi infrastructure, but LC PDS NICs would be a good place to start your research. It's a 68020 subset of the 68030 PDS. I've got a comparison diagram of the control signals involved.

AFAIK, NIC implementations were all based on standard, well documented chipsets. IIRC the drivers for them were very similar.

Video's an entirely different ballgame, but the very inexpensive Color Pivot II/IIsi might make a good expansion chassis candidate for your Pi-NIC notion. The Futura II NuBus cards had connectors on them for DSP and NIC daughtercards. They used a single Slot ID for Video/NIC operations.

Dunno what you'd use for the connector offhand, but grafting the PCB for your R-Pi smack onto the empty FPU socket might just fit. The FPU interface should to give you most, if not all the signals required. A 10x10 Seeed PCB there could drop your Pi down into the contorted cubic defined by chassis/mounting ear/bucket/FDD bracket configuration constraints. Excellent building block playtime to be had there.  [] ]'> 

Silly WAG: Tangential musings, but it might be interesting take look at the Video ROM and dedicated video-RAM in the SE-30 schematics and memory mapping. Don't really know what I'm talking about here, but it may shake some thing loose for someone competent. If dedicated video memory accesses might be a subset of the video ROM's full address space, its socket might a possible wedge point for bit-banging? Folks regularly ask about getting Compact Mac video out and onto an external monitor. The SE/30 might turn out to be a candidate for finally doing so?

 

[jack]

An FPGA board may be a better candidate than an Raspberry Pi for this; give you some programmable logic to interface with the hardware, then you can translate that at a software level to ethernet.

On such a board, there may even be a chance you could throw out video out all using the FPGA chip (bit-banging as jt mentioned).

Also: welcome aboard!

 

[jack]

LC PDS NICs would be a good place to start your research. It's a 68020 subset of the 68030 PDS. I've got a comparison diagram of the control signals involved

Mind sharing? Got an idea I want to hack on sometime...

 

[Trash80toHP_Mini]

Sure, LC/020 should be the main section of LCIII/030: 030 PDS -> LCIII PDS Adapter?

That one is flip flopped from this graphic in another thread. It gets the bulk of the control signals lined up across from each other as well as can be.

/monthly_03_2017/post-902-0-58138200-1489530836.jpg">View attachment 12055

Biggest of the obvious problems with the LC <-> 030 PDS of the si/30 twins is that the LC slot is hardwired at Slot ID E, which conflicts with the PseudoSlot Video implementation in both systems. Could wire it up to another interrupt, but the drivers will have to be hacked for that too?

 

[MacDoctorFL]

Thanks Guys! A lot to consider.  I'm not a programmer or an engineer. Just thought with all the effort in figuring out the Protocache1 thread that a combined device based on a super cheap SBC (either R-pi, FPGA, or x86) could be affordable.  Even was thinking if a modified VNC client or USB to video via serial port could support 640x480 8-bit color. If I'm remembering the serial port can run at 115k baud. Should be fast enough?? Ive seen a couple video on the fly type devices on hack a day.

https://hackaday.io/project/21097-arduino-video-display-shield  or https://hackaday.com/2011/10/06/a-masochistic-video-card/#more-57802

https://hackaday.com/2015/09/01/arduino-video-over-2-wires-for-under-50-mesa-video/

 Via VNC http://https://hackaday.com/2015/11/27/streaming-video-on-an-apple-iic/#more-179461

FPGA (may not apply but offer a direction)  https://hackaday.com/2015/09/09/video-fpga-with-no-external-ad/#more-168923

 The best for last:   https://hackaday.com/2015/07/09/viewing-a-macintosh-ses-video-on-a-modern-computer/

 Could some kind of extension be made to lie to the Mac SE/30  that a video card is attached. To send out put to a second computer i.e. SBC/FPGA.

 

[Trash80toHP_Mini]

A lot to consider.  I'm not a programmer or an engineer.

Neither am I, obviously. I just like to play with the building blocks.

That said, came up with a notion for a ProtoCache1 tangent that would be suitable for FPGA/PiPlaytime. Bolle's fabulous PowerCache adapter prototype is designed to sit on a WrongAngled IIsi form factor PDS card. Not everyone has the NIC to support it, so I've been toying with a riser card for his development board with general purpose (outboard the box) prototyping connectors for these and any other projects for the si/30 twins. Illustrator playtime and a new hacks thread coming up! [] ]'>

 

[Trash80toHP_Mini]

View attachment 14681

Here's my notion for an SE/30 or IIsi prototyping setup. The EuroCard PDS connector allows full size card testing with the signals passing through provisions for a PCIe connector.

PCIe is cheap as heck and a 10cm x 10cm Seeed board form factor made with the PCIe edge connector makes for very inexpensive prototype PCB runs. Either type of card (or both types at the same time) is plugged into the riser through the opening in the chassis that's outlined in orange.

By itself, this passive riser would act as a replacement for the NIC employed as the base for Bolle's ProtoCache1 development board, with or without the prototyping connectors.

If no cards are installed in the ProtoBoard's expansion slots, the Bucket can be installed without interference.