Theory thread: How would you update C64?

[Weasel Fierce]

Its an alternate timeline. You get the task of updating the C64 one last time before the 16 bit systems really take over.

[ross]

Originally Posted by Weasel Fierce

Its an alternate timeline. You get the task of updating the C64 one last time before the 16 bit systems really take over.

Dual (stereo) SID.

Just imagine this beauty in the days:
[ Show youtube player ]

[Megalomaniac]

Some sort of processing boost, either by running the 6502 faster or putting in a second one. Slower clock speed was the only area where it lagged behind the Spectrum and Amstrad. For graphics and sound it was already good enough for 2D games - for any-scrolling-but-vertical games it was a match for the ST - so I'm not sure improvement there was a priority

[TCD]

I think the C128 is pretty much that.

[Samurai_Crow]

Alternate timeline? Sure! Bypass C128 and make GeoRAM the standard expander for addressing more RAM as well as I/O. This would have allowed card-slot boxed C64s.

The $DE00 address space becomes a bank selector for the $DF00 page. Normally, only 2 addresses are used for page selection that way but opens up the possibility for more than 24 bits of expansion in the future, by using more than 2 bytes of address paging. GeoRAM could address 16 MiB of addresses as is, adding more bytes of addressing up to 2^(256×8 bits) would have been possible.

Re:2nd SID chip
I had a Dr. Evil SID Stereo cartridge. It was available. It had a jumper to make it run from the $DF00 page instead of the $DE00 page.

Re:faster CPU
The PLA was using 4 MHz of memory access as it was. 1 MHz for CPU, 1 MHz for ALU, 1 MHz for VIC2 video and 1 MHz for character generator. There was no way to add more to the main bus. The only practical way to fix the speed was parallel processing.

The fact that the C128 had a separate memory bus for 80 column video, moving the memory fetching off of the main bus, freed up half of the bus cycles for 2 MHz. Even that was already insufficient.

That's why adding I/O addressing and added coprocessor support would have been superior.

[Predseda]

C 65

[Thomas Richter]

I always wondered why the C64 came with this ugly and limiting 16 color palette. It's earlier competitor (the Atari 800) had a (relatively) large palette of 128 colors. Thus, what VIC-II really misses is the possibility to adjust the 16 colors to select from - it would not take much, just 16 additional registers that contain (as in the Atari) the hue and luminance of each possible color. This was not out of reach and would have been feasible at its time - and I wonder why it was delivered with this fixed palette.

[Gorf]

Originally Posted by Samurai_Crow

Re:faster CPU
The PLA was using 4 MHz of memory access as it was. 1 MHz for CPU, 1 MHz for ALU, 1 MHz for VIC2 video and 1 MHz for character generator. There was no way to add more to the main bus. The only practical way to fix the speed was parallel processing.

Well, that depends on, "when" we are doing this - from 1988 on RAM was more fast enough to support 8 MHz memory access and double the bandwidth ... with a upgrades Cpu one could also combine the CPU/ALU step into one cycle and same goes for ViC and character generator as long as the character I stored somewhere else... all this combined would give us 4x speed with at least 2x resolution.

[ImmortalA1000]

Originally Posted by Weasel Fierce

Its an alternate timeline. You get the task of updating the C64 one last time before the 16 bit systems really take over.

They already did, it's called the VIC-III 256 colour chipset inside the $249 C65

[Promilus]

Natural C64 upgrade is 65C816 and DMA controller (so supercpu and reu basically). Replacing VIC is something like creating whole new machine rather than upgrading C64. Along with 16bit CPU and big RAM it would be nice to have really decent drive speed as well and of course dual SID as it wouldn't make it anything fundamentally different and less compatible. So basically everything ultimate does.

[Weasel Fierce]

Thinking along more humble lines is there a way to do more RAM while being compatible but without the awkward mode shift of the 128?

[Pyromania]

I upgraded my C64 in the late 1980s. I upgraded it by selling it and getting an A500. Best C64 enhancement I ever did and it only took up a little more space on my desk.

[Samurai_Crow]

Originally Posted by Weasel Fierce

Thinking along more humble lines is there a way to do more RAM while being compatible but without the awkward mode shift of the 128?

GeoRAM was much cheaper and simpler than the 1750, 1764 and 1700 RAM expanders from Commodore. It also used less power so it worked with a standard power supply.

[gimbal]

Join forces to squeeze the last interest out of the platform. A C64/MSX duo computer. GO!

[ImmortalA1000]

Originally Posted by Weasel Fierce

Thinking along more humble lines is there a way to do more RAM while being compatible but without the awkward mode shift of the 128?

This might interest you, the ill-fated Imagine who were working on their Bandersnatch 'mega game' hardware for the Spectrum that is seen in a documentary were also working in parallel with a C64 add-on. The Bandersnatch hardware wasn't much more than a RAM expansion for the C64 actually.

If you boil it down to its essence the C64, for me personally, comes down to VIC-II, SID and minimum [and only] specification of RAM of 64kb. I suppose just doubling up the machine specs you could implement 16 more colours in the palette, 16 sprites per scanline OR 3 colour 24x21 pixel hi-resolution sprites instead of monochrome, have an 80 column mode fast character mode (2kb), giving you 4 colours in something equivalent to 4x8 pixel character blocks in size on the screen, 4 global multi-color colours not just 2 per sprite/screen, dual 6581 SIDs with individual filters for each channel, 2mhz CPU, 128k RAM. That is already much more useful than what the C128 left you with.

Removable left/right borders, just like the VIC-20/Amstrad CPC allowed, would also be nice.

What would be essential is Color RAM to have 4 possible locations in memory just as screen RAM does, otherwise you can't double buffer in 1/50th or 1/60th. If that doesn't work then a hardware character shift of 1 column and/or 1 row for character based screens which would effectively give you actual hardware scrolling (C64 only has hardware pixel offset, not hardware scrolling).

Built in turbo loader as fast the one used by Crazy Comets (fastest loading commercial game on tape, around 75 seconds to load). Interface to allow 1551 disk drive. Black breadbin case with red function keys. Remove that junk CRT tube in the 1701/1702 monitor and get Sony to make your monitors if you are going to charge more than a top of the line Sony CRT TV for them too.

I think that would have made a nice mid lifecycle update after 5 years on sale etc.

[Weasel Fierce]

Originally Posted by gimbal

Join forces to squeeze the last interest out of the platform. A C64/MSX duo computer. GO!

I unironically want this

[Tigerskunk]

I think the C64 is great as it is. And in 1985, there was already the Amiga. So no room for a real C64 successor.

But if it was another timeline without the Amiga and ST: a C64 II with 256 kb, double SID and a 16 color palette that could be chosen from let's say 512 or 4096 colors, released in 1986, would have gone a long way, imo.

[Promilus]

When it comes to "real" c64 successor I'd go with TED+sprites or VDC with sprites. Or just C65.

[roondar]

Dual or triple SID sounds (ahem, pun not intended) like a great idea.
Other than that, faster CPU/VIC (so better colour/sprites). Basically a C65

[Weasel Fierce]

Originally Posted by Tigerskunk

I think the C64 is great as it is. And in 1985, there was already the Amiga. So no room for a real C64 successor.

But if it was another timeline without the Amiga and ST: a C64 II with 256 kb, double SID and a 16 color palette that could be chosen from let's say 512 or 4096 colors, released in 1986, would have gone a long way, imo.

I think even the 512 palette would go a long a way along with the other changes as a sort of "peak of the 8 bits".