Building a Terrible Fire 536 Accelerator

I already have a Terrible Fire 534 accelerator, but Terrible Fire created an improved 68030 based accelerator for Amiga 500, Atari ST and similar machines called the TF536. This accelerator uses a 100MHz crystal which clocks the CPU at 50MHz. Whilst it does not have an FPU like the TF534, it does have 64MB of RAM onboard, which is significantly more than the 4MB of the TF534 and more than I’ll probably ever need.

PCB Build

Blank boards for the TF536 can be purchased from Exxos Store which already have the bottom passive SMT components fitted, I also purchased the CPU socket from there. There is a BOM available on the forum on the same site and I bought all the other required components from DigiKey.

All the SMT work was soldered on using a 0.2mm soldering iron tip to do each pin and a magnifier (plus lots flux!). When cleaned up the board looked like this:

Then all that is needed is the CPU socket and the pins to plug it into the 68000 socket on the motherboard. It is at this point I used my Pi Xilinx programmer to flash the firmware. The CPU itself is the newer ceramic 68030 I purchased for my TF534.

One particularly bad day with extreme lack of sleep later and I managed to solder the pins upside down onto the PCB, so I had to desolder them and fit them again. But the end result turned out OK, this is just before I made that mistake:

Testing

When I plugged it into my Amiga and turned on the power, I was greeted with a second of flashing colours and then a black screen. Nothing else happened. So, time to break out DiagROM.

DiagROM booted up but showed that the RAM on the TF536 was not being detected. I then tested by going into the RAM edit mode, manually entering some data in the memory area of the TF536 and then refreshing it. The data I had written was not what was being returned. It was clear that some bits were not being written / read correctly. On closer inspection I found a few dry soldering joints on the memory buffer ICs. After reflowing these, DiagROM discovered the full 64MB and a RAM test of this area passed.

I suspect the Xilinx programming is designed to halt the Kickstart boot if the RAM is not detected properly.

So, I then switched back to Kickstart 3.1.4 and got the familiar boot screen Amiga fans known and love. Next up, AmigaTestKit to check the RAM, this was after several hours of running. All clear:

Then we load up SysInfo to get some quick benchmark numbers:

Finally for a stability test I ran the game “Frontier: Elite II” and let the intro / demo of that play out for a few hours. It all checked out OK. So, I decided to run some real punishing tests by doing things the Amiga 500 was definitely never designed to do.

Doom

Whilst Doom technically may have worked on the TF534, with Workbench running in the background there wasn’t enough RAM to try it. Now I had 64MB of Fast RAM I could actually try this out. You can download ADoom for free here and I already have the WADs to go with it from previous ownership of the game. From here it was pretty easy to get Doom 2 up and running.

Whilst it wasn’t very fast (I think 5-10 FPS with max resolution) it was surprisingly playable.

SCUMMVM

How about something else a little taxing. I love the LucasArts adventure games, one of my favourites as a youngster was Sam & Max Hit The Road. But there was definitely no Amiga 500 version. So, I tried the PC CD version with full speech enabled in an ECS version of SCUMMVM.

The cut scene animations were a little laggy and mouse clicks didn’t always respond properly, but I was surprised how well the machine handled this. I would expect a 486sx/25 to probably have similar performance. The performance was likely held back by the ECS chipset and the slower speed it was running at.

All in all the TF536 is a great card and is definitely staying in my Amiga.