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How About: Full Banks Standard?


rje
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The FAQ notes that 512k banked RAM is the planned shipping configuration.

i reckon this is a cost consideration.  But isn’t it likely to cap programs to only use 512k?  It feels like a handicap, however minor.

 

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It's extremely minor, and easily overcome. 512k is still an embarrassment of riches for an 8-bit computer, and it means that it can act as a baseline for compatibility, and pretty much any game or application that will work within 2MB can work in some form at 512k. A program can detect the number of banks and load extra data into the higher banks for quicker access. This can make having more RAM act as a cache to mass storage to cut down on load lag. Or extra RAM can enable things like more music and sound effects, so the user experience is enhanced. If a program absolutely needs 2MB to be functional, that would definitely hamper its adoption, and chances are it could have been more intelligently designed to make it work in some form in 512k.

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Posted (edited)

That's sort of what I am thinking, except on the opposite side.  TOOLS as well as games will be written for 512K.   They COULD do RAM cache, but I suggest it's easier to make do without, unless you absolutely have to.

As you say, it is an embarrassment of riches, and so we can live without the other 1500K, and I think we will.  😞

Your examples have some merit though.  I could see a music or effects cache, and if there's a cheap and easy way to leverage that, then I could see it.  Assuming ... well assuming lots of things.  

This is a weird ecosystem.  But the part that's NOT weird is how like Commodore this process is.  Take a stab at things, have possibilities, but in the end you don't really know what sort of impact it will make.

***

I use the banks statically: I load them once and use them.  But I could see a cached solution.  Hmm.

Edited by rje
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What is the cost difference for 3 more 512x8 SRAM ICs? 20 bucks US? If it's 10% of the total cost, I'd say it's worth it to make them all 2Mb machines, and make that the lowest common denominator, because the LCD is what programmers will write for. Quadruple the embarrassment!

Having said that, here's some assembly language code to determine the max RAM bank number:

LDA #FF
STA 00
STA A000
SEC
SBC #40
CMP #FF
BNE #F4
STA 00
CMP A000
BEQ #07
SEC
SBC #40
CMP #3F
BNE #F2
RTS

Edited by Ed Minchau
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Lowest Common Denominator is what I'm thinking about.  I would REALLY want to use the full 2MB, and if I do that, I won't want to write code that accommodates a 512K system... except I'm kind of hamstrung, aren't I, into coding to LCD, in which case forget the 2MB version... But the developer inside of me says "make a decision, do one or the other and stick with it".

Note that I wouldn't have been thinking this way if Eight Bit Guy hadn't specifically TALKED ABOUT IT in his videos on the VIC-20, Plus/4, et al.

 

 

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Posted (edited)
On 6/20/2022 at 12:19 PM, Ed Minchau said:

What is the cost difference for 3 more 512x8 SRAM ICs? 20 bucks US?

Total?  Somewhere around there, it seems.

Quote

 If it's 10% of the total cost [...]

Nickels and dimes add up.  But yeah. 

Edited by rje
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Another cost consideration is the move to a single FPGA design. Quadrupling the RAM would likely be much more than a 10% increase in cost. And even with discrete through-hole RAM chips, as we have seen, the market for chips like this has gone whackadoo (I apologize for using such a technical term), with demand outstripping supply by an order of magnitude (or more!), as chip fabs put their limited resources to producing high-quantity, high-profit components for modern systems. Prices for the kinds of chips used in the X16 have doubled in the last couple years, if not tripled or worse! And supplies being how they are, there may simply not be enough RAM chips available to put more than 512k in every unit. We could even be looking at a lottery situation for completed X16 units at first.

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There's also the kit factor. If you get a board with pads/vias for more RAM, you can try your hand (literally) at adding the RAM yourself. Not that everyone will want to do this or even be able to do it.

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Removing 3 RAM chips and the support demux also saves considerable board real estate. No telling which way Kevin will take the official board, but the prototype PCB for my design left them out to save on board space and fit the whole thing into a mini-ITX form factor. I left a header and jumper for expanding the RAM if I ever felt the need. $20 extra in BOM cost does not mean $20 extra in sticker price - I hope everyone realizes this. When you start manufacturing these things you have to add margins to account for production losses (bad components, bad boards, customer returns, and on, and on).

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On 6/21/2022 at 8:43 PM, Wavicle said:

Removing 3 RAM chips and the support demux also saves considerable board real estate. No telling which way Kevin will take the official board, but the prototype PCB for my design left them out to save on board space and fit the whole thing into a mini-ITX form factor. I left a header and jumper for expanding the RAM if I ever felt the need. $20 extra in BOM cost does not mean $20 extra in sticker price - I hope everyone realizes this. When you start manufacturing these things you have to add margins to account for production losses (bad components, bad boards, customer returns, and on, and on).

Last I heard, the official story is that the sockets would be there, but that only one out of the four would be populated. So unless the plans have changed, the chip select and other hardware will be on the board. We're literally just talking about 3 memory chips.

 

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