Denial

If I use 1" as the pitch, the total length ends up 9.9" for 6 slots:

I still need to shift the ports to 1", but I went ahead and placed the original and new designs on github.com: https://github.com/go4retro/xpander-vic Thanks to Orangeman96 on the forum for prodding me to provide the files I've held off on shifting the ports, since the board is routed in two sp...

srowe wrote: ↑Sat Apr 20, 2024 3:18 am I've just checked the spacing in my Arfon expansion unit, the slots are 1in apart.

I was thinking the same. Nice round number, easy to place on the PCB grid, gives a bit of space between, and keeps the design from being too long.

I'd recommend just passing [pins 20 and Y] through exactly like all other lines. There exist cartridges which misuse either pins 20 or Y on their edge connectors to simplify routing. If one cartridge connects 20 or Y to +5 V and one other cartridge connects the same pin to GND you short the power s...

I wouldn't attempt to fit the largest available cartridges in it because of the extra cost involved - I have an 80 column cart that is about 2x the thickness of a standard one. People can always sacrifice one slot for something big like that. As long as the spacing is large enough to accommodate ca...

Revisiting my X-Pander 3 VIC design as I plan to get it up on Github and perhaps consider a re-run. It had bugs and I'd like to get them fixed before I put something into the wild. Is there a preferred port spacing? Also, as I recall, pin 20 and pin Y, though noted as N/C on many pinouts, were in ac...

As I remember Jim made 100 of these, but noticed the dip-switches were to close to the cartridge slots, so you could not plug in a standard cartrdige fully. You can still buy this for $22 a piece and I got one some years ago: https://store.go4retro.com/non-functional-goodies/ See the notes at the b...

Sorry I didn't see this earlier. It's very much appreciated!

Let me know how I can help get this working on real HW.

Jim

As the linked posting illustrates, the inverters are open collector, which is very important for the bus. You could somewhat accomplish the same thing by putting pullup resistors on all the VIA pins connected to the bus and switching the output to an input when you want to send a '1',, but the 6522 ...

Does the ARM automatically connect to the DRAM and handle refresh, or do you implement your own refresh scheme?

Jim

Does the cart allow FLASH in any bank besides 5?

Jim

I'd fix this by using an 29F040b, which only requires 12 bit unlock codes. It's still 512kB, and I believe it still available. That way, the unlock can be done from any bank.

And, I think they are less expensive that your current option.

Jim

Here's the repo for UltiMEM: https://github.com/go4retro/UltiMEM And, the register description is here: http://www.go4retro.com/products/ultimem/ Essentially, each of the various memory segments (RAM 1,2,3 | BLK1 | BLK2 | BLK3 | BLK5 | IO2 | IO3) can be set to read/write RAM, R/O RAM, ROM, or nothin...

I'll put the UltiMEM schematics and such into github, as it sounds a lot like your current project (8MB FLASH, 1MB RAM, bankable blocks and rams and IO segments)

Jim

Ingo's dedicated opinion is not a good basis to get things done, Well, given that these things are passion projects, not financial items, I think it's as good a basis as any if one expects Ingo to do the work. The promise of open source was that lots of people would contribute to source code, but t...