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VERA CHIP


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49 minutes ago, Varun said:

Hey community,

I just wanted to ask, if you wanted to, where could you buy the VERA chip. It would be quite useful for a project that I am working on

It's not for sale as a standalone product yet.  The idea has been floated by the CX16 creators, but you're not likely to see it sold separately until it's first been included in an integrated system (the X16 or X8, for example).

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  • 2 weeks later...

Well, maybe we can continue this thread with speculation and recommendations for the add-on version for when it comes time to think about that.

Obviously, for form factors, they'll need to cover the basics, which would include...

8 and 16-bit ISA,

Apple II expansion slot

Apple IIgs expansion slot

BBC Micro Tube Interface

Commodore VIC20/64/128 User Port

Commodore Vic20/64/128 Cartridge Slot

Commodore VIC20/64/128 VIC/VIC II/VIC IIe Socket Riser Domino

MSX Expansion Cartridge

Atari 800/XEGS "Big Cartridge" Slot

Atar 8 Bit Serial I/O module

Sinclair ZX Spectrum/Timex-Sinclair 2048-4096 Expansion Module

 

May I also suggest dropping the PSG and PCM channels, so that they can be put on a different FPGA?  That way we could split the thread into separate proposals.

Possibly more latar.

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On 9/27/2021 at 8:00 PM, Kalvan said:

Well, maybe we can continue this thread with speculation and recommendations for the add-on version for when it comes time to think about that.

Obviously, for form factors, they'll need to cover the basics, which would include...

...
Commodore VIC20/64/128 User Port
Commodore Vic20/64/128 Cartridge Slot
Commodore VIC20/64/128 VIC/VIC II/VIC IIe Socket Riser Domino
...

This is five different form factors ... which is, it would appear, part of the jest ... but in all seriousness, this can be boiled down to Commodore Vic20/C64/C128/PET User Port and C64/C128 Cartridge slot ... and once you put one in a C64 cartridge slot, it might as well be a 512KB geoRAM card as well, because you have two expansion pages and only need 32bytes for Vera, while geoRAM uses one page and the first two bytes of the other one.

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On 9/27/2021 at 8:24 PM, BruceMcF said:

This is five different form factors ... which is, it would appear, part of the jest ... but in all seriousness, this can be boiled down to Commodore Vic20/C64/C128/PET User Port and C64/C128 Cartridge slot ... and once you put one in a C64 cartridge slot, it might as well be a 512KB geoRAM card as well, because you have two expansion pages and only need 32bytes for Vera, while geoRAM uses one page and the first two bytes of the other one.

I had originally planned to to wait until the team was ready, but what I was toying with was, depending on form factor and addressing capabilities, anywhere from one to seven unpopulated 128K RAM DIP sockets, for use as extra Video RAM.

The idea is not so much to add all new modes to the hardware as to (at the customer's option) maximize the capabilities of the current modes in the FPGA.  With three of those DIP sockets filled, there is enough Video RAM space for all 128 sprites at 64x64  4-bit pixels with no scanline limits, with the tilemode or bitmap depth to match, for example.  Stick this version of VERA in an Atari 520/1040ST, and (in theory) you have the architectural missing link between the Apple Lisa/Macintosh XL and the first-generation Sharp X68000, hardware feature-wise, at least.

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On 9/27/2021 at 6:50 PM, Kalvan said:

I had originally planned to to wait until the team was ready, but what I was toying with was, depending on form factor and addressing capabilities, anywhere from one to seven unpopulated 128K RAM DIP sockets, for use as extra Video RAM.

The idea is not so much to add all new modes to the hardware as to (at the customer's option) maximize the capabilities of the current modes in the FPGA.  With three of those DIP sockets filled, there is enough Video RAM space for all 128 sprites at 64x64  4-bit pixels with no scanline limits, with the tilemode or bitmap depth to match, for example.  Stick this version of VERA in an Atari 520/1040ST, and (in theory) you have the architectural missing link between the Apple Lisa/Macintosh XL and the first-generation Sharp X68000, hardware feature-wise, at least.

The VERA registers currently have two unused bits that could be (in theory) allocated to addressing more RAM. 17 bits supports 128K. One more bit would allow a second 128K. Two more bits would allow a third and fourth 128K.

That doesn't mean that there are sufficient resources to handle 19 bit addresses. I don't know. But to access more than 3 extra banks of 128K would require more effort from a quick perusal of the documentation. And even if those resources did exist, there probably aren't enough IO pins available to access three external 128K RAM chips given what we've been told about the resources used and things that were removed in favor of other features. A quick search reveals there are 32 pins on the first 128K x 8 static RAM chip I could find. To select from three of them would require at least one more chip select pin.

What would be nice is if VERA HDL becomes available so that one could target a larger FPGA that could support more internal video RAM.

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On 9/27/2021 at 8:50 PM, Kalvan said:

I had originally planned to to wait until the team was ready, but what I was toying with was, depending on form factor and addressing capabilities, anywhere from one to seven unpopulated 128K RAM DIP sockets, for use as extra Video RAM.

The idea is not so much to add all new modes to the hardware as to (at the customer's option) maximize the capabilities of the current modes in the FPGA.  With three of those DIP sockets filled, there is enough Video RAM space for all 128 sprites at 64x64  4-bit pixels with no scanline limits, with the tilemode or bitmap depth to match, for example.  Stick this version of VERA in an Atari 520/1040ST, and (in theory) you have the architectural missing link between the Apple Lisa/Macintosh XL and the first-generation Sharp X68000, hardware feature-wise, at least.

The Video RAM is the 1Mbit (accessed as 128Kbyte) Single Port RAM built into the FPGA. That is how one linebuffer can be displayed at the 50MHz dotclock while the next one is being generated with two layers and that many sprites. "More Video RAM" would not be about including more RAM on the cartridge, it would be about finding a member of the family with a larger embedded SPRAM.

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