PiStorm on the Macintosh SE

[AlexCL]

Starting a thread to track my experiments on using the PiStorm on the Macintosh SE.

Just today I tried a new configuration and got much better numbers on SpeedoMeter...

I removed the original CPU and put in a socket so I can run both the original CPU and the PiStorm.

It could be installed using a CPU relocator PDS card which should be simple to build as all the 68000 pins are on the PDS...just have to ground the BR line to let the PDS mounted CPU take over apparently.

Only floppy access is working...I have to lock the disks as write errors will cause them to fail after a while...

Sound and Video work and I've been able to play a number of games using an external 800K floppy and BMOW's floppy emu together.

Working (apparently):
Internal Video
Internal Sound
ADB (Trackball, BMOW ADB-USB Wombat [wireless mouse, keyboard])
Soft ROM for CPU (speeds up graphics and floating point)
68000, 68010, 68EC020 CPUs (all native 24-bit addressing CPUs, 32-bit addressing CPUs not working)
Dove 30 Control Panel (appears to enable caches on CPU)
Reading from 800K floppies on external floppy drive port
Reading from 800K floppy images on internal floppy ports with BMOW Floppy Emu

Not Working:
SCSI devices not seen.
Writing to 800K floppies (format disk fails and disk write errors if disk is not write protected).
HD20 (Floppy HDD) emulation on BMOW Floppy Emu not working.
68020, 68EC030, 68030, 68EC040, 68040 CPUs (all 32-bit addressing CPUs 68040 can't do 24-bit addressing and may never work with stock ROM. The Mac will get to the grey screen with a beep but never get to the cursor or flashing floppy icon (with 020, 030).

Untested:
Serial Ports (I bought some D-9 ports to create loopback plugs but haven't gotten to it).

Possible Future Features:
ROMINATOR Style ROMs with ROM Disk for booting
Virtual video card with HDMI out from Raspberry Pi
Virtual SCSI interface for HDD images
Virtual Sound Cards
USB connectivity through Pi Ports
WIFI passthrough
USB to RJ45 wired network
Virtual Memory using real Pi Memory
RAM Card emulation
32-bit ROM Hack to allow clean ROMs
Emu68 Baremetal Raspberry Pi CPU Emulation (much faster JIT CPU emulation).


My biggest roadblock is that I'm not an electrical engineer or programmer so I'm still basically using a stick to poke what exists rather than creating new solutions...there is a lot of potential and if Raspberry Pi 2 W's ever get released again this would be a sub $100 solution.

 

[pfuentes69]

It's nice to see this moving for real. I heard about this project but I thought it was not yet working.

I understand SCSI is not yet functional, right?

How it looks like in the inside? A photo would be great to see.

Txs, and keep telling us!

 

[AlexCL]

 

[AlexCL]

I'm not at home but the photo above is from Discord a while ago.

I bought a power/video cable from eBay and extended the wires so I can work on the motherboard on the outside of the case (and the high voltage CRT).

This is how the computer looks until I start the CPU emulator on the Raspberry Pi.

One of the creators of the PiStorm used a Raspberry Pi Zero 2 W and was able to install it in his Mac SE and close up the case...mine is probably too tall with the extended socket...

 

[AlexCL]

This video was when the PiStorm didn't start normally...it starts up reliably now without having to reboot several times.

 

[Drake]

Is the scsi bus not working because the instructions for pistorm aren't there?
Or simply because accelerating the cpu to X speed throws access timings off?

 

[pfuentes69]

Thanks. Please tell us more!

Has this been tested in other models, such a Plus or a Classic?
Can it emulate a 68030?

 

[AlexCL]

Is the scsi bus not working because the instructions for pistorm aren't there?
Or simply because accelerating the cpu to X speed throws access timings off?

Unknown at this time...the SCSI chip runs warm and no devices are recognized except for the Macintosh on Device 7. If I put the 68000 back in SCSI works again...so it doesn't appear to kill the SCSI chip.

 

[AlexCL]

Thanks. Please tell us more!

Has this been tested in other models, such a Plus or a Classic?
Can it emulate a 68030?

I've only seen it work on a Mac SE.

I believe there were issues getting the classic to work...

The software can emulate a 68030 but it just stops after the boot beep on the grey screen...there may be some way to tell the emulator to start in 24-bit Addressing mode...but it isn't documented.

 

[AlexCL]

The PiStorm as I have it configured now replaces the CPU and mirrors the RAM and ROM and puts it on the Data and Address Buses through the CPU socket.

The BBU talks directly to ROM and RAM so it may be causing issues/bottlenecks.

 

[AlexCL]

Compact PiStorm with a Raspberry Pi Zero 2 W...might fit in Mac SE case without modification...not confirmed.

 

[AlexCL]

I removed the physical RAM from the Macintosh SE and used the write through cache ram from the PiStorm for the first 4MB. The system appeared to load from disk and I was able to insert a virtual floppy after the external floppy stopped.

The static and sound come from the BBU reading the RAM directly...and it not being there...interesting.

 

[AlexCL]

As a follow up I removed the ROMs...

The Mac booted normally using soft ROM from the PiStorm with the real ROMs physically removed.

This means testing modified ROMs in software and getting the real ROMs off the address/data buses to eliminate false positive results...

 

[pfuentes69]

As a follow up I removed the ROMs...

The Mac booted normally using soft ROM from the PiStorm with the real ROMs physically removed.

This means testing modified ROMs be all software...

Does it keep doing the scary noises when booting without ROM, or just stands still until the PiStorm service is alive?

 

[AlexCL]

Does it keep doing the scary noises when booting without ROM, or just stands still until the PiStorm service is alive?

I put the RAM back in before I took out the ROMs...without physical or soft ROMs it just would stay at a black screen.

It will boot without physical ROMs.

I wonder if you could could connect the SIMM slots directly to the PDS slot so the BBU would have access to the PiStorm memory...hmmm.

Also you could read the video and sound buffers from memory and put those out separately I guess.

I'm sure most of this wouldn't work...but it is fun to think about.

 

[Towmater]

Is there a use for the Pi's HDMI output?

 

[AlexCL]

Is there a use for the Pi's HDMI output?

In theory a graphic card emulation could be written...there is video output on the Amiga and experimental video out on the AtariST.

I'm the only person I know who is working on getting the PiStorm working on the Macintosh right now...my programming and electronic skills are limited...I am an oldschool Mac person who perferred GUIs to CLIs.

 

[68kPlus]

View attachment 9685

Sorry this isn't related, but what kind of external floppy drive is this?

 

[AlexCL]

Sorry this isn't related, but what kind of external floppy drive is this?

External 800k drive. This label is the only marking. It came with a Mac SE purchased on eBay.

 

[AlexCL]

I was able to use RamDisk+ to create a startup disk...I was able to copy a file to the disk which does not work on real floppies. In addition it keeps the system in RAM so you can insert a new disk on a single drive system.