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Today I finished off the board (except for the floppy disk separator board) and tested it with 4K of RAM. I plugged it in and it fired up beautifully! CompleteWith4K.jpg Here is what I was greeted with when I turned it on: Boot12K.jpg Now I have to build the separator and acquire a floppy. I have pu...

Here is info on setting the jumpers for Single or Dual sided floppies: Im not sure about X5-X14. Can anyone in the know verify this jumper for double-sided?

Also, R7 is 1K ohms.
/Jeff

Here is my parts list, complete with links where to buy components. Here are two handy chip placement guides.
This one is courtesy OSI. UPDATE: revised color PCB layout file; added RAM chips and jumpers
/Jeff

I too picked up a 610 replica and a pair of data separators from Grant and am going to use them to add a floppy drive interface (and optionally, RAM) to my recently acquired C1P. The second separator will be used to add a different floppy drive to my C1PMF, hopefully restoring it to full functionali...

@ Grant: Your design (or, perhaps, Bill's) sounds much more versatile than mine. It sounds like with it, you could add as much RAM or ROM to a system, essentially anywhere in the memory map as desired. Would it sit on the 48 pin bus, or would it use the 40 pin expansion? or both??? Are you going to ...

Hi Bill, thanks for the reply! I have been busy breadboarding just one of the memory chips (the one at $2000 - $3FFF) and have modified the circuit as follows: Bread.jpg I put jumpers on the 600 board in place of the 8T28's and haven't used any buffers on the data bus either.....just for simplicity,...

Yesterday I took my Superboard out of its anti-static bag so I could start testing my memory board. Sadly, the entire keyboard was now suffering from 'E' key syndrome (no longer working). So I plugged in my soldering iron, and located my solder sucker and went to work. Keyboard Repair.jpg The last p...

BillO wrote:trimming the long arms of the nylon "+" on the Futaba's plunger.

Wonderful outside the box thinking, right there!

/Jeff

Personally, I plan to leave the first bank empty in some cases, so I don't have to modify the system I am upgrading. And in another (my C4PMF) I plan to have it replace a 527 board, which will only be 24K (in the first 3 banks), as my 541 board has 24K on it which would collide, and since the 541 bo...

Hi All, I have been spending some time designing a memory board for the challenger line. I have come up with the following design and would love some input from the hardware guys on this site. My concept is to divide the memory into 8K blocks and use 28 pin sockets and 2764 Eproms and GM76C88 SRAMS....