Commander X16

On 10/27/2022 at 8:01 PM, Kalvan said:

So long as the expansion architecture allows expansion cards to augment, rather than simply replace the capabilities of VERA and the sound interface (merely removing scanline limits and/or allowing the display of all sprites at maximum size, or adding in an extra wavetable or PCM chip while still allowing normal use of the geometry channels and the YM2151, as examples), ...

On 10/27/2022 at 7:47 PM, TomXP411 said:

I intentionally picked 60 pins on Proto 3 because it's uncommon and a lot of pins.  This prevents A2 & ISA cards and I think none of the console carts will fit in here, maybe Famicom?  But hey, it is its own thing, so please, only X16 stuff!

On 10/28/2022 at 2:01 AM, Kalvan said:

rather than simply replace the capabilities of VERA

On 10/29/2022 at 6:33 AM, neutrino said:

Should the pins for the existing expansion bus be insufficient it would be possible to reduce the number of ROM pins by providing a ROM address instead of a fully decoded output.

On 10/29/2022 at 6:33 AM, neutrino said:

It can be handled by the same setup the 3Dfx cards used on the PC. Physically route the video output through an expansion card, and then connect the monitor to the output connector.

On 10/29/2022 at 4:46 PM, BruceMcF said:

RTFM, it is analog video outputs from Vera.

On 10/29/2022 at 4:46 PM, BruceMcF said:

Look at the picture. It is a ROM address, not a fully decoded output.

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  Target 512KB of RAM. Future systems will be limited to this, with 2MB for "power user" systems, such as developers
  


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  Rough estimate of retail sales is: "Christmas of next year." 
  

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The purpose of the development run is really two-fold. One is to get the hardware into the hands of early developers. We already have a lot of folks developing on the emulator, but it's not a complete substitution for the real thing in all cases, so the idea is to get a head start on development for the final release.

Secondly, I want to make sure the system is stable. We have had the system running code for some time now, but only in the last six months were we able to actually validate that everything was working correctly. Wavicle and some other members of the Discord team had found that the YM2151 was not terribly happy at 8MHz. While it was working, it was dropping some data at times, and reads from the IC were also not terribly reliable. I sort of knew this might happen, but had never been able to test to a level where I could fully validate it. They were able to come up with a clock streching circuit to effectively slow reads and writes down to 2MHz for slower devices. This change is now on the dev board, and has been tested for a little while now. The really cool thing about this addition is that pretty much any device that will work at 2MHz or faster will now run directly on the bus! IE, you could cram a SID or two on an expansion card if you really wanted to.

We want to chase any other gremlins out of the system before shipping, so the other part of the dev run is to have folks beat on the HW to make sure everything is working as we hope. I know 95% is the magic number for still not finished, but I really meant 95% done routing this particular board, not the HW itself. What I believe is more at question, is what software will ship with the system at launch.





This is where the magic is, IMO. 2MB of RAM happened, because of math, not because it was necessarily a good idea. I mean, who doesn't want more RAM, but do you need it? The banks for RAM and ROM are stored in an 8-bit shift register, so I have 256 'banks' of 8k on the RAM available. This equals 2MB. Likewise, the ROM has a 16k window with 256 banks, so 4MB of ROM. In reality, they could both be RAM or ROM, but the two windows are there. But as stated, I just put 2MB on there, because I could, not because it was a good idea. The ROM was originally only 128K, then 512K, but now the whole range is accessible via the expansion port.

However, as the system has evolved, we know loading data from the SD card is plenty fast for you to swap out data in the 512k range. The only real reason to have 2MB would be for laziness. � 512k should be plenty for most games, but, David actually came up with an interesting idea. Let's say you're a developer, with 2MB, you would have enough RAM to run a compiler environment in the top 1.5mb, then compile and run the code directly on the system, but only using the lower 512k. I can imagine an OS like GEOS would benefit from the RAM, and I think eventually, this machine could be used for music composition, so 2MB of RAM would be handy for more sample time. Pretty sure the Roland S550 I used to own in the 90s had 2MB or heck, maybe 1MB. Point is, there are times when you might be able to use it, but for gaming, 512k is probably going to be fine.





The next versions of the system will likely be capped at 512k of high RAM, so the message we want to send to developers is use 512k. For power users, this version of the system will always be the go-to version as it will allow you the most flexibility. But, the more cost reduced versions will be less capable, but still run all of the games available and likely other SW with reduced capacity. IE, I have less sample time, or less RAM for GEOS, etc.





There are a lot of exciting tools in the works as well for the system, so I really hope that this is one of the most complete 8-bit homebrew systems ever, before we launch! This will give developers a really easy path to getting stuff up and running, and will offer features that no other 8-bit machine has seen. I think it was Steve Ballmer that said, "It's the software, stupid!", in this case, I think he is correct. We should have a lot to offer before day 1, and I really think it will only grow from there!

On 10/29/2022 at 11:20 AM, neutrino said:

The picture just says ROMB0 - ROMB7 and the FAQ specifies 32 banks ie 5-bits but not how much will be present on the expansion bus. There's no pinout description nor any schematic asfaik. So the board isn't self evident in function.