Vic 20 memory

[carlsson]

I can't recall what the switches 1-7 on the homemade one will do, but the 16K Cardram should fit your purposes. You want one of the two blocks to be mapped to BLK5 - meaning one out of four DIP switches should be on and the other off. The other block usually should map to BLK3 in the same fashion, but a few 16K cartridge games will instead load the second half into BLK1. If you want to load Scott Adams' text adventures, you need to enable BLK2 and BLK3. Which block is which is not really important, as long as the two 8K blocks are mapped to one area each.

 

Supposedly the homemade one works in a similar way, but I would've expected eight switches in order to work as 2 blocks x 4 switches.

[WicoKid]

So, weekend warrior on this but had recently gotten a VIC 20 and with limitation using the SD2IEC as far as loading game cartridges I found a VIC-1111 16K RAM Cartridge. When searching online in 2021, I could only find a picture of an opened but already modded 8K expansion cartridge. Below is the picture of my VIC-1111 16K RAM...as I see it, the 4 pads on to the right middle top of cartridge must the ones that are dipped switched on the 8K version; the red arrow points to the pad that is default jumpered (removed in this picture) on the 16K version (VIC-1111) and the green arrow shows where to jumper (pad/switch 1) for cartridge loading ($A000 RAM/ROM cartridge space). 

 

I had been been loading the cartridge images into basic memory. Now it works fine. When you change this, the space available for basic is once again 3583 bytes, so you have to use FB20 (commodore file browser) not FB20-8K. Then once loaded type "sys 64802" as above to start the game. 

 

I'm still working through the games, so likely to have some issues pop up with the 16K games I guess.

 

Thank you Atari  Age/above thread contributors.

[WicoKid]

Yes...I did have problems with the 16K files. But....Wow...this...now it works as two independent 8K blocks that can be assigned to Blocks 1,2,3 or 5. Printing a case now. I saw posts about the VIC-1110 8K modification and adding switches to the VIC -1111  16K  but no details....didn't think it would be this straight forward. In this picture its set for 8K to Block 2 ($4000) and 8K to block 1 ($2000).

 

Any 3K options/additions with this? Still looking through OLD posts, lots of references to long gone pictures.

Edited March 30, 2021 by WicoKid

[carlsson]

3K expansions use the pins for RAM1, RAM2 and RAM3 so it would require additional logic and wires to the connector, so unfortunately I don't think this one is a suitable candidate for that. Not that there is a ton of programs for 3K expansion anyway.

[Touio]

 

Hello guys. I also have the Vic-1111 but I don't know how to place the switches to activate block 3 and 5. In the manual it says that they are 3 and 4 but they cannot be activated both at the same time. How do I do it then?

[carlsson]

What the manual refers to is that each 8K block can only be mapped to one block at the same time. With two groups of four DIP switches (or at least pads) you would set one group to BLK3 (third switch) and the other group to BLK5 (fourth switch). BLK4 is the ROM and I/O area which are available on separate pins on the cartridge slot anyway. You should probably never have more than one switch enabled within each group of four, and also not point both groups to the same BLK.

[Touio]

Thank you very much. I understand then that the configuration for block 3 and 5 in this?

 

OIOO IOOO

 

or

 

IOOO OIOO

 

[carlsson]

Yes. To my knowledge, either of those two would work. You can always POKE 24576,x:PRINT PEEK(24576) and do the same for 40960 to verify that you got RAM connected. If not, you would get 0, 255 or some random value back from the PEEK.

[Touio]

15 hours ago, carlsson said:

Sí. Que yo sepa, cualquiera de los dos funcionaría. Siempre puede POKE 24576, x: PRINT PEEK (24576) y hacer lo mismo para 40960 para verificar que tiene RAM conectada. De lo contrario, obtendría 0, 255 o algún valor aleatorio del PEEK.

All perfect. Thanks for helping.