Replace Basic with Action

[gozar]

Since Action! has an 8K footprint, what would it take to replace the built-in basic with Action? You would have to add some circuitry to bank in the other 4K banks, so I have no idea if it's even possible. It would be nice for the U1M too, but that would probably require a firmware upgrade.

 

One of my What If fantasies is What If Atari had replaced Basic with Action (along with add 80 columns) in the XL line?

[Rybags]

Probably just use the original cart board which then takes care of the bank select stuff. Would need to take a copy of the /CCTL line which goes active on page D5 accesses. Bank changes could occur regardless of whether Basic is in/out via PORTB and whether a cartridge is present but it shouldn't matter.

 

The OSS carts can be switched off completely to allow access to the Ram by certain writes to D5xx - this wouldn't work if it was incorporated as a Basic replacement.

 

 

To do OSS carts in Ultimate 1 Meg - Pretty sure it can only do a contiguous 8K Rom part to $A000. OSS carts work by having the lower 4K switched among 3 possible parts of the Rom. To do this in U1Meg would need 3 * 8K images with the top 4K the same in all. Then a stub of code would need to live somewhere to do the cart switching... my suggestion would be to use the OS to do it.

[+Larry]

Metalguy66 (Ken) made a small adapter board that plugged into the mobo. He had one for XL and one for XE. I *think* it was possible to do a 4-in-1, but I don't remember all the details. You might contact him. I've got one for the XE that I've never installed.

 

-Larry

[ricortes]

A [74LS175, 74LS00, 74LS02]. You probably wouldn't want to do that though. I think the hardware design for the XEGS carts is superior on a couple of levels. It only uses two chips IIRC [74LS374, 74LS00} and gives you more banking bits. It isn't a perfect design for OSS carts since it natively it doesn't switch 4k banks, but it could be rewired to switch exactly like the OSS carts or as Rybags ~mentions, you could just use a large ROM and bank large sections with fixed non banked portion replicated in every bank.

Edited November 14, 2016 by ricortes