FPGA as graphics card?

[Mutz03 Zockt]

On 12/25/2021 at 12:30 AM, TomXP411 said:

That’s to make it easy to use in a desktop ATX case. 

yes, indeed, but fo rthese couple of people, who actually would put it into a ATX case, they need to put a AVR on the board...

thats kinda my problem...

[BruceMcF]

On 12/24/2021 at 6:43 PM, Mutz03 Zockt said:

yes, indeed, but fo rthese couple of people, who actually would put it into a ATX case, they need to put a AVR on the board...

thats kinda my problem...

Do you think it will only be a couple of people who will put it in a case?

And what is the big problem about putting an 8bit microcontroller on the board anyway? I could see the complaint if it was a 32bit or 64bit microcontroller that was more powerful than the system it was put into. Sure it isn't the variety of 8bit microcontroller used, eg, for the IBM-AT keyboard interface, but part of the vision of the system was to use off the shelf ASIC parts wherever possible.

[Ed Minchau]

On 12/23/2021 at 5:28 PM, Mutz03 Zockt said:

Hey everyone



i am actively following the X16's developing for now over 2years i beleve, and i am heck of exited to finnaly get my hands on this amazing computer.



when i saw the first videos, i was really exited, but then after one after another problem apeared, wich the Devs have solved with FPGA and microcontrollers, i got a bit upset.

its not like i have much better ideas how to solve these problems, and i have been tinkering around a lot with electronics trying to get a better way of solving these problems.

but David initially said, he does not really like to have FPGAs and AVRs in the Computer, and i agree with that, it is kinda counterintuitive, having a little Microcontroller in yoour computer wich essentially has almost the same performance as the whole computer.

as i already said i dont really know much of solutions, but i would love to gather some smart people, to maybe come together, and try to find ways, to not have to use AVRs, and FPGAs.



i know it is really dreamthinking, and unrealistic, but deam would i love to have a complete hackable, and realistic retro computer.



anyway, i am really happy how it turned out none the less, and maybe, now, when we do not get the cases with the powersupplies, we can maybe also just get rid of the AVR at least.



Regards from switzerland

Toby

Look at it this way: in the 1980s, Commodore had their own chip fabrication plant.  That's how they produced things like the VIC chip and VIA chips for audio and video for the VIC-20.

The VERA daughterboard is definitely something Commodore could have done in the 80s, though it would be a much bigger board.  And of course we're already using 512kb RAM ICs, which for Commodore would have been an enormous PCB flooded with 2kb RAM chips.  Point is, Commodore could have produced VERA, and all the rest of the Commander X16.  Their only real obstacle would be the RAM, and SD storage was just a dream back then.  An FPGA like VERA would have been a factory-programmed gate array rather than field programmable, or several such ICs.

The ATtiny used for Reset and power on wouldn't have been present on Commodores because of the external power box feeding a single voltage to the computer, but if they had needed something like that it would have probably been done with a special-purpose chip that they fabricated themselves as well.  It isn't doing a whole bunch of 16 bit or higher math, and might have been implemented with a bunch of TTL logic gates instead.  If they were putting 2Mb of banked RAM in a machine, the case would already be big and would contain lots of PCBs, so what's one more?

[Mutz03 Zockt]

On 12/25/2021 at 11:23 PM, Ed Minchau said:

Look at it this way: in the 1980s, Commodore had their own chip fabrication plant.  That's how they produced things like the VIC chip and VIA chips for audio and video for the VIC-20.



The VERA daughterboard is definitely something Commodore could have done in the 80s, though it would be a much bigger board.  And of course we're already using 512kb RAM ICs, which for Commodore would have been an enormous PCB flooded with 2kb RAM chips.  Point is, Commodore could have produced VERA, and all the rest of the Commander X16.  Their only real obstacle would be the RAM, and SD storage was just a dream back then.  An FPGA like VERA would have been a factory-programmed gate array rather than field programmable, or several such ICs.



The ATtiny used for Reset and power on wouldn't have been present on Commodores because of the external power box feeding a single voltage to the computer, but if they had needed something like that it would have probably been done with a special-purpose chip that they fabricated themselves as well.  It isn't doing a whole bunch of 16 bit or higher math, and might have been implemented with a bunch of TTL logic gates instead.  If they were putting 2Mb of banked RAM in a machine, the case would already be big and would contain lots of PCBs, so what's one more?

ok look, i can understand this, but for me the Vera Board is liek a "magic box" where things happen, and i cant really hack it, nor understand it as easely as the rest of the system. wich for me and my reason why i want to get the CX16,  it is for me kinda upseting.

BUt i can understand your point, yet am trying to build a Graphics card myself.



also a thing is, the whole system is based of parts wich were avaiable in the 80s.

fpgas and AVRs werent.



i am trying to make a CPU driven GPU off a Motorola 68K. if it works it will have similar functions as the VERA board, but will be really easely hackable, and also debuggable.

will probably take up more space than the Vera board.

but i dont know if it ever gonna work, due to me not being a educated electronics engineer. im just a nerd doing dump shit, wich works some of the times...

[BruceMcF]

On 12/26/2021 at 2:56 PM, Mutz03 Zockt said:

ok look, i can understand this, but for me the Vera Board is liek a "magic box" where things happen, and i cant really hack it, nor understand it as easely as the rest of the system. wich for me and my reason why i want to get the CX16,  it is for me kinda upseting.



... also a thing is, the whole system is based of parts wich were avaiable in the 80s.

fpgas and AVRs werent. ...

The VIC-II and the MOS 8563 were both pretty much "black boxes" where things happen. Understanding down to the level of what register to set to get what effect in the VIC-II, MOS 8563 or Vera seems to be similar levels. Obviously if Dave owned his own fab, and if the X16 was expected to sell in the millions, Vera could be done as a +5v compatible ASIC chip.

The whole system based on parts which were available in the 80s was not part of the vision of the project ... that would be a different project. That's not to say that other project is unworthy or anything, but "build to the extent possible with DIP ASIC parts currently in production" and "build with parts which were available in the 80s" are two different goals that are going to disagree substantially.

Indeed, the alternative "chips available in the 80s" goal is violated quite extensively by the X16. Byte addressed 512KB Static RAM chips were not readily available in the 80s, and that's a big part of the chip count of the "big" chips in the system. Nor were 14MHz rated 65C02 or 6522 chips.

[Wavicle]

On 12/25/2021 at 2:23 PM, Ed Minchau said:

The VERA daughterboard is definitely something Commodore could have done in the 80s, though it would be a much bigger board.  And of course we're already using 512kb RAM ICs, which for Commodore would have been an enormous PCB flooded with 2kb RAM chips.  Point is, Commodore could have produced VERA, and all the rest of the Commander X16.  Their only real obstacle would be the RAM, and SD storage was just a dream back then.  An FPGA like VERA would have been a factory-programmed gate array rather than field programmable, or several such ICs.

A component with the capabilities of VERA in the 80's would have been prohibitively difficult to bring to market. The tooling to create a die large enough to hold 1Mbit of SRAM just didn't exist at the time. It's difficult to appreciate how many Moore's-Law-Doubling-Transistor-Count-Cheaply cycles we've gone through since then. Had Commodore sunk every dime of profit they ever made into the custom tooling necessary to produce such a component at the node size achievable at the time, they would still have been hundreds of millions of dollars short of what was needed.

A 1989 VERA would have to have been its own board. Even then it would have been very difficult and prohibitively expensive. 8-bit systems were all about not being prohibitively expensive.

[BruceMcF]

On 12/27/2021 at 3:36 AM, Wavicle said:

A component with the capabilities of VERA in the 80's would have been prohibitively difficult to bring to market. The tooling to create a die large enough to hold 1Mbit of SRAM just didn't exist at the time. It's difficult to appreciate how many Moore's-Law-Doubling-Transistor-Count-Cheaply cycles we've gone through since then. Had Commodore sunk every dime of profit they ever made into the custom tooling necessary to produce such a component at the node size achievable at the time, they would still have been hundreds of millions of dollars short of what was needed.



A 1989 VERA would have to have been its own board. Even then it would have been very difficult and prohibitively expensive. 8-bit systems were all about not being prohibitively expensive.

As with the MOS 8563, it would have to be a chip with its own DRAM bus, but running it that fast would have been a "challenge", pushing it more toward the Feonix solution of having the dedicated video RAM being a wider data path than 8bits.

[Wavicle]

On 12/27/2021 at 10:53 AM, BruceMcF said:

As with the MOS 8563, it would have to be a chip with its own DRAM bus, but running it that fast would have been a "challenge", pushing it more toward the Feonix solution of having the dedicated video RAM being a wider data path than 8bits.

Moving the video RAM off-chip presents a packaging problem. 32 VRAM data pins + 15 VRAM address pins + 17 system interface pins (8 data, 5 address, CS, RWB, clock, INTB) + video clock + 5 pins video out (analog RGB, Hsync, Vsync) + 2 power pins puts the lower limit of pin count at 72. Even more to support audio and a mass storage interface (and a few others like the VRAM RWB pin and whatever else I can't think of off the top of my head). There may have been 80 pin DIP packages, but the largest I am aware of is the 64 pin MC68000. VERA would have been too large for a through-hole DIP package and would have been a surface mount component. At some point we have to admit that it would look sorely out of place among all other 8 bit components on the PCB. VERA's capabilities are defined more by what the FPGA it is using today can do than what would have been a practical graphics solution in the age of 8 bit systems.

[BruceMcF]

On 12/27/2021 at 4:59 PM, Wavicle said:

Moving the video RAM off-chip presents a packaging problem. 32 VRAM data pins + 15 VRAM address pins + 17 system interface pins (8 data, 5 address, CS, RWB, clock, INTB) + video clock + 5 pins video out (analog RGB, Hsync, Vsync) + 2 power pins puts the lower limit of pin count at 72. ...

I don't think the audio would be on the same chip, and AFAIU, there's no functional connection between the audio registers and the video registers, but if address pins were column / row strobed like the MOS 8563, that still hits the speed.

The MOS 8563 was limited to 64KB and it had a system bus interface based on an address and a data register with 37 logical registers, with a byte based local address bus and row/column strobed local memory address, but that arrangement wouldn't have nearly the bandwidth required by Vera.

 

[Edmond D]

On 12/27/2021 at 12:36 AM, Wavicle said:

Even then it would have been very difficult and prohibitively expensive. 8-bit systems were all about not being prohibitively expensive.

An opinion more on the financial side from a 80's teenager:



I agree that a 1980s VERA would probably have been an expense the market couldn't bear at that time. I scrapped together $100 CDN in the early 80's to by a datasette, I remember most game carts going for $40-$60 which put them out of my reach as a youth. A 1541 was way out of the question for me, so I lived with tape. The load times were not painful, perhaps in part because an unexpanded VIC just didn't have too much memory. While my family's economic situation wasn't direr, my hobby had to compete with my three other brothers, two of which played hockey (which was the norm for kids in Canada.) Sports gear was expensive too, but there was a strong second-hand market since most kids grew out of gear before it wore out. I think the used computer market didn't really exist, or may not have existed for me. Machines seemed to be kept around and upgrade mania wasn't a thing then since new processors didn't come out every other week.

I think there would have been another limitation in the displays used at the time. Most low end systems required an analog TV, others could support a monitor. Creating a board that may have required a new "monitor" to be purchased might have slowed its adoption. I'm glad that aspect of a retro system is gone, not being forced to purchase a old CRT or a bridging device. 



The other factor is a computer that would be able to use a 1989 VERA. I've read that the C64 or Apple II might be able to use a modern VERA, but until it ships that's just an idea that has yet to be proven. I don't think a VIC 20 with VERA would be a useful system if possible. 

 

Finally, any product has a target market with a price to hit that crowd. The general consumer market always likes a low price. I remember the early 80's 8 bit marketing was either price, the number of colours or the RAM size. Companies may have wanted my geeky teenage self to go buy something, but it was normally cost prohibitive to me. ?