I got a new batch of the 6502 expansion PCBs. I made a small change regarding the patch needed for disk drives, it is described on the construction page.
I still need to have another batch of 2364 adaptors made. They're
out of stock now.
Finally I got a few PCBs for the C2N232I to build a prototype. So
far it's working nicely, but now Marko will have to do changes in the
firmware and the software, and after this is done I will have to order
Wolfgang Moser's article on
the 6502 RAM/ROM expansion board has been republished in the Commodore Free Magazine #6!
I removed the order page. In case you need PCBs or (spare) parts, mail me: please visit my contact page.
I added a page about the usage of the 6502 expansion board in 1541-II drives. It's listed on the index page. Also, I added a paragraph about troubleshooting this board to the construction page. There was also a bug in the new flash software that corrupted the data in the FlashROM. There is a new fixed version now instead, download it from the disk drive page.
Thanks to a short holiday I was able to finish a new version of the flash program for disk drives! It includes several bugfixes and enhancements, read the included history file for details.
Also have a look at Tim Schürmann's report on Dolphin DOS usage
with my hardware (in German
language). Thanks, Tim!
Some updates after a long time: Marko Mäkelä wrote an improved flash program for the PET and VIC20 platforms. You can find it on Funet. Thank you very much, Marko! I also added two new products to the order page, the A570 2MB RAM expansion and the PET video adaptor. I made only very small quantities of those products and most are sold already. If there is enough interest I might make another batch.
A new project was added: A 2MB RAM expansion for the A570 CD-ROM drive.
Several updates to the web pages. Wolfgang Moser published an independent test report on his site, have a look if you're interested in his opinion and experiences.
While testing different floppy speeders a problem with the expanded floppy drive RAM became obvious. To make use of RAM in the area $2000-$7FFF a little hardware change and an updated GAL chip is needed. The changes have been added to the construction page and to the DIP switch configuration guide.
The flash program for the disk drives is finished. Read about it on the disk drive page.
There is a construction page now that explains how the components have to be installed on the board. I also moved the prototype pictures and news to a separate prototype page.
I shipped the first few devices to customers and they're all very satisfied. You can also download flash programs for the PET and the VIC-20 now.
I got the PCBs for this and other (6540, 6550 and 2364 adaptors) projects this week, now I'm waiting for the parts to finish a few boards. I had enough parts here to test one of each PCBs and all of them work as expected. Especially with the 2364 adaptor this is a nice surprise, I never made a prototype of it.
I just finished the second prototype with the option to use narrow DIL-28 SRAM chips which can be found on many old 486 mainboards. Since the board design is error free now, I'll try to find a cheap manufacturer for the PCBs now.
I created two other sets of GAL equations, one for the VIC-20 and another one for the 1541 and compatible models (2031, 1540, 1570, 1571, 128D, 128DCR). In RAM mode, both work as expected, but I didn't test the FlashROM yet (again, I need to write flash programs first). There are problems with fitting the device into the limited space of the VIC-20, especially the old orginal version with the big heat sink. In the floppy drives, everything should fit well except in the slimline models 1571 and 1541-II.
I finished a very simple flash program, with this I was able to copy the PET ROMs onto the FlashROM, and the PET can now work without its original ROM and RAM chips.
I added equations for Flash support into the GAL, and after that none of the configuration switches worked anymore! I wondered why putting back the previous content into the GAL didn't help as well, so I suspected a hardware problem. Seems the GAL forgot that it is supposed to have internal pull-ups on its inputs, because the circuit worked as fine as before when I soldered in the "optional" resistor array into the holes near the DIP switch.
The board worked on the first try with the 27C512 and the W24257 SRAM chip. Everything else also seems to work (RAM size configuration to 4, 8, 16 or 32kB, ROM banking). The GAL does not yet have support for programming the Flash ROM. Below are some pictures of the test scenario.
Currently a 6502 works fine on the board with the LS245 installed. Next I'll program the GAL chip and test the board with a 27C512 EPROM (yes, it's pin compatible) and the SRAM, if that works, I can be sure that the board is okay, and start working on flashing software.