keith
So the very first A500 I had been testing on since the beginning of the project had a Bug Katcher installed. It turns out that I wasn’t really using it, but I left it plugged in anyways. I’m not sure...
Sweet success, card works 100% in different DUT(Amiga)
So I think the Amiga 500 I was testing with has problems. I’m not sure precisely what or why but Today, I dropped my new A501 replacement card into a known-working Commodore Amiga 500. It fired up immediately no...
Logic Analyzer probe loading seems to fix boot issue
While I had my logic analyzer connected to my memory card tonight, I noticed that I no longer had the white screen hang on bootup problem that I’ve been plagued with since this card came in. As a matter of fact...
Stress testing the memory board
So I’ve written some assembly in the monitor software I’ve been using, and I’ve just created a large loop to see if I can get the card to fail. I’m still having plenty of problems on bootup, but...
Workbench booted up with the new card installed!
For those of you who might not get the significance, workbench loads a number of libraries into the extended fast memory on bootup. As you can see in this image below, more fast memory is actually being used than the...
RTC Progress
RTC appears to be working and keeping the date and time across cold-starts. I picked the Epson RTC-72423 which is about a $6 chip, but is obviously directly compatible with the OKI Semiconductor MSM6242B. The design...
Found potential race condition on writes
After looking at datasheets for the 273 latches used and 74act74 flipflop used, the worst case propagation delay is something like 12.3ns. But my NAND gate ACT00 logic which is triggered by the same CAS signals has a...
Populated PCB with fix for unneeded inverter
Lots of progress but little time to talk about it. Here’s the fully populated card installed. There were two issues identified so far with the PCB design. One, the battery holder silkscreen was upside...
PCBs have arrived!
Just in time for Christmas, the PCBs have arrived from China. I used Seeed Studio (Fusion PCB Service) and they look pretty good. Here’s the first look at them. I’m just about to solder one up, so wish me...
PCB ordered from Seeed Studio
I placed the order late last night for the PCB! The PCB design is obviously finished, fully passes the kicad DRC checks, the problems with the footprints were solved. I’ve decided to go with Seeed Studio’s...
Found problems with incorrect footprints used for some chips
So I received all of the SMT parts today, and attempted to verify that I’ve used the right footprints for the parts. This was a worthwhile effort because I found a few different problems. Also, digi-key shipped me...
All SMT parts on order, rough idea of parts costs
So all the SMT parts have been ordered for the prototype PCB. Once they come in, I’ll be testing the placement of the parts on top of a printed layout to see if the chips/parts match the layout — if there...
Finalized schematic and PCB is coming along nicely
SMT parts will be ordered soon. Once they arrive, I’ll double-check the pad design/placement is good, and then order the PCBs! Everything is coming along swimmingly and I should have a prototype PCB in a few...
Moving from prototype on a solderless breadboard to PCB soon
So I’ve got a reasonable number of memory tests passing with the prototype solderless breadboard. There are some minor issues that are mostly related to the stability: Sometimes my memory board steps on the built...
Sometimes the amiga recognizies my ram board, some very basic memory tests are passing
So I’m starting to make some progress here, but I still have some troubles with my expansion board prototype. For the first time, the initial exec-rom-based check passed, and the memory auto-configured. This...
Testing shows databit 10 is always stuck high on commodore amiga expansion
With help from Ralf on this comment I was able to Disable the memory by no-longer grounding PIN 32, and sometimes forcing CE high on the SRAM chip. Boot a workbench disk, and then break it on startup. Insert a disk...
Amiga Guru Meditation number 00000003.00C06560
Found a bad flip/flip replaced it, and now I’m on my way. The amiga appears to be getting past the initial boot stages including the ram memory checks! I see the blue screen, and the disk drives starts loading...
