5200PicoCart (a8PicoCart rework)

[pirx]

@electrotrains devised a very cheap and surprisingly good cartridge emulator based on super cheap (we are speaking under $2) clones of PiPico like https://www.aliexpress.us/item/3256804090698520.html?gatewayAdapt=glo2usa4itemAdapt

I have such a device and it works like a charm.

I asked the author if it would be possible to modify the project to work for 5200 and it seems to be doable - there are more address lines required, but there are some signals missing in 5200 like Phi2, R/W, CCTL (?), so it should be OK. I know nothing (practically) about electronics and designing PCBs, but I know a bit about programming on 5200, so maybe someone could make a PCB, I'd modify/write the A8 firmware to run 5200 carts and we'd have a beautiful and super inexpensive cart emulator.

 

This is a call for the hardware specialist to look at this small but mighty project.

[0078265317]

This will be like a cart for running rooms like the atarimax sd?

[pirx]

this is the basic idea - you upload cart files to the cart (pipico) via USB (PCs see it as an external disk) and then run them from a small menu on 5200. pipico has 16MiB "disk", so a bunch of carts will fit.

the cart is then loaded to pipico RAM and served to 5200 from there. RAM is not large (<256KiB), so really big cartridges will not work, but I am not sure if there are many (any?) of such huge games for 5200.

[Wrathchild]

The absence of the cart bus and r/w lines means you have to 'fake' communication between the 5200 and the ARM when compared to how the existing UNO/Pico carts work (this had come up before).

 

And this really only applies to the initial menu selection stage, e.g. entering text for a title search, conveying menu selections.

At its simplest I would think using a page in the ROM area to simulate a 128 byte range and then treating access to them as a 'Send Character'.

e.g. access a command byte to instigate a 'Send Text' mode and then repeat 'Send Character' until they are done,

      either the address&0x7F of the value after the 'Send Text' gives the length or just use an 'End Text' command byte.

 

[pirx]

I see, I did not know about this difference.

I think even something simpler would work - it would suffice to poll a single byte in the cart area, maybe the copyright date as it is read only once. or the start vector.
I suppose text search is not that necessary, just some numeric selection and/or cursor moves. As far as I understand this can be done entirely in software, so no additional hardware in the cart is needed, just pipico hooked up to the 5200 cart.

 

As a first step, the pipico software could start just a single cart (e.g.: file with a certain extension). It would be a useful cart already.

Edited October 19, 2023 by pirx

[coachbrj]

I am not a tech guy, so if this question is too dumb to answer please ignore it. But could what you are asking/doing lead to this... 

 

 

[pirx]

no, this is a much simpler idea, not a console replacement, but a programmable cartridge replacement using super cheap parts. like poor's man atarimax cart.