Denial

Ok, so obviously they still all come with 5K, 3.5k usable for basic.
What I mean is in the current VIC community, do most people only have up to the origonal 16k expansion.
Or is it common for people to have their VIC expanded to 32 or 35K?

Basically, if I were looking at making a game, is there a best or optimal specification to code for.
Or is it largely reduntant because people ether use emulation or have their VIC fully expanded?

Hi Garry68,

Wirh all the modern options for RAM expansions, I guess it is very common to have it ‘fully’ expanded to 35 kB.

Cheers

I'd say go for 35K-expansion if that is what your game needs. All modern expansions of at least the last 10 years provide that (MegaCart, FE3, Penultimate, UltiMem, ...) and people serious about using the real VIC will have or get that expansion anyways. All the others can use VICE.

If you like the challenge of programming for the 5K-machine that's fine also. If your game fits in a smaller expansion that is nice as well, but don't get blocked creatively because you need 24K instead of 16K-expansion or 35K instead of 32K.

Added note: 35K-expansion means the VIC then has a total of 40K available (5K built-in + 35K expansion). This gets mixed up a lot. I suspect you both mean expanded by 35K, not expanded to 35K (which is not really possible).

tokra wrote: ↑Thu Dec 16, 2021 3:36 pm Added note: 35K-expansion means the VIC then has a total of 40K available (5K built-in + 35K expansion). This gets mixed up a lot. I suspect you both mean expanded by 35K, not expanded to 35K (which is not really possible).

Yes, sorry. I meant expanded ‘BY’ 35 kB.

Cheers

My personal development philosophy (w/r/t the VIC-20) is "Pretend that it's 1980." My VIC-20 Etsy shop literally implores visitors to "Vote Carter/Mondale this November!" This means that I'd theoretically top out at 16K. Sure, it's always been possible to go beyond that, but I didn't even see cartridge expanders in my local game shop in 1980.

I can't make a case for anybody else to adhere to my philosophy, and you should use what your project needs. But I'm not so sure it's a slam-dunk that every VIC-20 user or retro-computing hobbyist has a 35K expander. Everybody on Denial probably has one, we who focus on the VIC-20 enough to want to read and post on a VIC-20 forum. I'd bet there's still an inverse relationship between a project's memory footprint and the number of people who can use it.

I was thinking about seeing if I can convert my 'Trapped' game for the Vectrex to the unexpanded VIC.
This is just shy of 5k on the Vectrex and I already have an idea of how I would do this on the VIC.
https://www.youtube.com/watch?v=ZU2LigCTyus
https://drsnuggles.github.io/jsvecx/?rom=Trapped

But I also have another idea that would probably take quite a bit more than that. So I may aim for 40K for that one.

This has been asked many times before, I think last time, the consensus what 16K was the most common and the minimum expected. Authors should move up to 32K if they need it creatively (I did for Popeye) and 35K was more of an outlier (I think only Doom needed it then), a lot of cheap 32K expansions were around.

Since then we've had penultimate so I guess 35K isn't such an issue now.

btw, I've posted a poll for this on the Facebook group which has more casual users - I'll post the results here in due course.

Thanks for this, The game I was thinking about making is a sort-of RPG that uses the same basic engin that I made for Trapped, but expanded to include indoor and outdoor locations. I started this also on the Vectrex before my vectrex died.

So the memory used basically turns into the size of the game. If 16K is the default I can aime for that, and expand if I need to.

I don't really use Facebook, but may have a look at the user group as well. Thanks again...

Welcome..it seems that 16K will give you the widest possible audience (other than unexpanded of course), however 35K seems to be the most popular expansion now, so there should be no issues targeting that either if your program needs the space.

Historically the RAM expansion was provided as 3k in lower part of BLK0 "OR" in BLK1(+BLK2)(+BLK3) because they was intended for expanding the BASIC usable RAM (using only 1 cart with poor RAM...).
In the modern era RAM chips are larger in size so it can be easy to use a lot of expanded RAM, but I recommend to don't use some configuration that, for historical reasons, couldn't be declared "standard".
For example, is uncommon mixing the +3k (RAM1,2,3) expansion area with the +8/16/24/32k (BLK1,2,3,5) expansion area:
please use +3k (or better: +8k) "OR" +8/16/24/32k.
If I have to choose I prefer a machine fitted with +8/16/24k ram expansion (in accordance with the necessity),If more RAM is required the 2nd next step is to mount the BLK5 (+8k), the 3rd step is to mount the RAM1,2,3 (+3k) and the 4th step is to mount the I/O2, 3 (+2k) for a maximum expansion of +37k unpaged RAM.

If more RAM/ROM is required paged banks can be used:

viewtopic.php?f=3&t=7706

viewtopic.php?f=10&t=9950

Hi Garry,

garry68 wrote:[...], if I were looking at making a game, is there a best or optimal specification to code for. [...]

I have put a condensed write-up of all possible/sensible RAM configurations into a sticky post in the Programming section of Denial, "VIC-20 Memory Layout". Please take a closer look at the notes below the diagram!

Especially with a view of a port from a Vectrex game, which would suggest the use of bitmapped vector graphics: that'd most probably require the use of most internal RAM ($1000..$1FFF, to be more exact) to hold the bitmap and an auxiliary address generator in the text RAM, implying you'd need a RAM expansion anyway to solve the resulting resource conflict.

Finally with regard to MCes mentioning I/O2 and I/O3 as possible extra RAM: this area is supposed to hold cartridge I/O registers and the only legit user is the cartridge firmware! Any inconsiderate writes (and even reads!) by 3rd party software might result in unexpected behaviour - more details found here: viewtopic.php?t=9181&start=22&hilit=I/O.

Greetings,

Michael

Mike wrote: ↑Sun Dec 19, 2021 5:27 am Finally with regard to MCes mentioning I/O2 and I/O3 as possible extra RAM: this area is supposed to hold cartridge I/O registers and the only legit user is the cartridge firmware! Any inconsiderate writes (and even reads!) by 3rd party software might result in unexpected behaviour.

It's true,
using the I/O areas for 2k of RAM expansion is a not standard use that can be dangerous if the HW set is not exactly as expected,
for maximum compatibility with physical HW i suggest to expand RAM into:
"3k in lower part of BLK0 OR in BLK1(+BLK2)(+BLK3)"

Other configurations are declared as possible (whit the related HW of RAM expansion), but not recommended (they can generate more HW complexity and/or implementation problems),
I agree with Mike

So as for the poll:

218 responses:

20 only have unexpanded machines
10 only have 3K expansion
13 only have 8K expansion
41 only have 16K expansion
9 only have 32K expansion
125 have 35K expansion

Therefore if you are targeting an expanded Vic, it would seem sensible to go down the 8K+ route using as much memory as you need to implement your program. i.e. 8,16,32,35 as mentioned in an earlier post.

My VIC has all of it's memory inside, no cartridges. Memory is installed at:
$0400 - $0FFF : internal so the VIC can use it
$2000 - $7FFF : internal
$8000 - $8FFF : two 4K banks to share with VIC as character RAM
$9800 - $9FFF : internal: IO2 IO3
$A000 - $BFFF : internal: Game RAM
$C000 - $FFFF : RAM banked under Kernal and Basic

Let's see, that's 61K.

+8K internal expansion here, dont have any other