Denial

You easily get a display of 40 (fairly readable) characters per line with a pure software solution; with either a full BASIC editor emulation like FAT-40, or as output-only oriented routines like those used in MG BROWSE.

Take memory expansion carts for the VIC-20. They are quite common, a good deal of programs exists which actually use them, but they do not require a special "brand" of a certain, say +16K, expansion. These all work equally well.

In converse, the different display adapter cards are not really compatible to each other, or to the 22 column display beyond simple BASIC programs. Most programs in machine language would simply not be aware, that enhanced display hardware was present, and why indeed should they have been? In those times, hardware abstraction at that level didn't interest anyone. Even the start address of screen memory was hardcoded in most programs.

So besides some text-oriented programs, most other programs, and certainly all of the games would not have "magically" been enhanced in resolution by the new hardware. And a program specifically written for a certain display adapter is tied to that hardware, severely limiting the audience. That program would have been better written for a machine natively supporting 80 columns.

The Data20 came with a disk of utilities that made use of the 80 column capabilities - word processor, terminal etc. ral-clan made a D64 of it a while back I think.

Another aspect is that you get dual-screen capabilities with these, you can run the 22-column and 40/80 column displays simultaneously. So that opens up possibilities for two-player games, etc.

Sorry guys maybe I wasn't 100% clear in what I was asking. I do know of the software only solutions and that there is little out there that supports 80 column hardware for the vic. I guess what I was wondering is if, for example, I made an 80 column cart that used the PET's display hardware, could I expect to maybe get some PET programs to work on the VIC? Is there anything useful/interesting out there other than a word processor, terminal emulator, or text editor? It sounds like the Data20 may be my best best as at least a little software exists for it. Thanks everyone for the feedback so far!

dano wrote:I guess what I was wondering is if, for example, I made an 80 column cart that used the PET's display hardware, could I expect to maybe get some PET programs to work on the VIC?

ral-clan wrote this in another thread concerning the Data20 80 columns card:

ral-clan wrote:Oh, I should mention that a bunch of PET games will run on the VIC with this 80 column cartridge. So can see what is going on in the game, but anything that POKES to the PET screen memory locations will need to be changed to the 80 column cart screen locations.

Emphasis by me. So there's still some re-work required.

Thanks for the link Mike, that pretty much answers my question. I had remembered some mention of PET games running on the VIC, and thought "maybe if a new 80 col chip used the same memory range as the PET it would allow programs that POKE to screen memory to run". Well, the PET's video is at 8000, right where the charater ROM is on the VIC. So that idea isn't going to work. That thread you pointed me to mentioned cloning the Data20 cart. I would be very interested in getting one if that ever happens!

As long as BASIC is involved, it is pretty easy to install a BASIC extension, which then diverts the address being POKEd, or PEEKed from the 32768 range to the correct screen RAM address of the hardware - that is how FAT-40 does its job in the soft 40-columns mode. There you can do, for example, 'POKE32768,0', and get an '@' in the top-left corner!

Of course that scheme cannot be easily applied to machine code, unless you're adventurous enough to write a 6502 emulator in 6502 code itself.

Mike wrote:Of course that scheme cannot be easily applied to machine code, unless you're adventurous enough to write a 6502 emulator in 6502 code itself.

That has already been done