Jump to content

Replace Basic with Action


Recommended Posts

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?

Link to comment
Share on other sites

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.

Link to comment
Share on other sites

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.



Link to comment
Share on other sites

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 by ricortes
Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

  • Recently Browsing   0 members

    • No registered users viewing this page.
  • Create New...