exxos's Atari, Amiga & retro forum

Edge connector fitted...


PiStorm & Pi installed...


Does it work?

Yes it does!


It doesn't look too bad sitting in the machine either.


The Amiga can be "instantly" returned to normal by just switching off and removing the Lazarustorm card.

Note: Modifications to the A500:

• 512K RAM installed in empty location on the motherboard along with decoupling caps.
• Jumpers changed to allow 1MB of CHIP RAM.
• JP6 bridged to add the CPU clock to the expansion port. (Why wasn't this done as standard? I just don't understand why it wasn't.)

P.S. Yes, I know Lazarustorm is misspelt on the case. Fixed for the next print.

Is that a rev 6 board in the A500 then @stephen_usher?

I looked t this for one of my A500s but the working one is a rev 5 & it seems that these external PiStorm upgrades often don't like the rev 5 boards :(

I'm currently stuck with diagnosing the rev 6 (at least until I can get a DIAGROM programmed...I don't have the correct adapter to program the 27C400 in my TL866 :roll: )

JezC wrote: 16 Feb 2026 17:16 Is that a rev 6 board in the A500 then @stephen_usher?

I looked t this for one of my A500s but the working one is a rev 5 & it seems that these external PiStorm upgrades often don't like the rev 5 boards :(

I'm currently stuck with diagnosing the rev 6 (at least until I can get a DIAGROM programmed...I don't have the correct adapter to program the 27C400 in my TL866 :roll: )

Yes, it's a Rev.6.

Well, if you have a PiStorm and a known working set-up then this could be an option, by installing Diagrom as the boot ROM for the PiStorm.

stephen_usher wrote: 16 Feb 2026 17:21

JezC wrote: 16 Feb 2026 17:16 Is that a rev 6 board in the A500 then @stephen_usher?

I looked t this for one of my A500s but the working one is a rev 5 & it seems that these external PiStorm upgrades often don't like the rev 5 boards :(

I'm currently stuck with diagnosing the rev 6 (at least until I can get a DIAGROM programmed...I don't have the correct adapter to program the 27C400 in my TL866 :roll: )

Yes, it's a Rev.6.

Well, if you have a PiStorm and a known working set-up then this could be an option, by installing Diagrom as the boot ROM for the PiStorm.

Interesting option - I hadn't realised that was even an option!

I do have a PiStorm adapter on order and a Zero 2W sitting ready for it to arrive...but it's not even shipped a week after the order went in :(

I wonder if you could get the PiStorm to map normal CHIP RAM into another location and have virtual RAM for CHIP RAM and use the RTC graphics out of the PiStorm to run the machine. Then that would mean that you weren't reliant upon working system memory to run the chipset tests. Hmmm.

I run an internal PiStorm on my A500 using Emu68 and Caffeine OS, I'd be interested to see if it runs externally on the Lazarus.

Use RGB2hdmi for the main display and PI HDMI for RTG.

Hmm.. the Emu68 Imager program is a pain to use and buggy as heck, so it took me all evening to get a working system with a large enough transfer FAT32 partition.

The partition manager bit doesn't work if Windows has display scaling turned on (which under Windows 11 is practically universally on). Even when it does work most of the time something goes wrong when creating the SD card image, such as the boot FAT32 partition being "too big", i.e. above 3GB. Or it can't boot from the Amiga partition (it's not the second partition on the drive). And the Amiga doesn't mount FAT32 partitions which appear after the Amiga partition, so you can't have a second FAT partition and have it be useful.

The system also stealthily installs a trial version of a commercial TCP/IP stack rather the free AmiTCP meaning that after 5 minutes you get a window appear saying that it's turning off and you should buy the full version. That's just bad form.

Other than that it's fine. ;-)

Well, the replacement Raspberry Pi4 arrived today, so I tried with the Emu68 installation which works on the Pi3B+. When it works it's very fast, as in over double the speed with well over 100x the speed of an A4000/040 according to Sysinfo. However, it doesn't work very often and it doesn't see the FAT32 partition on the SD card when it does.

When it doesn't boot the Amiga crashes with a chip RAM failure... Somewhat similar to the RAM access failure I was having then trying to use the Pi4 with the Atari firmware in the STFM.

I wonder if trying to use the Pi4 is a critical error in the Atari PiStorm development. Yes, it has a faster CPU but the GPIO latency is far higher. Even the Amiga PiStorm people don't really support it, for good reason.

@stephen_usher I've used a pi4 on my 500+ with the same OS that @rubber_jonnie uses. Whose name escapes me right now (the OS not RJ's name).

I removed the two usb and network port so it would fit internally whilst doing the installation.

Does your PiStorm board have flip-flops or latches? I guess that could make a difference.

Mine has 373s.