Speed of later models
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The 8-Bit Guy
- Posts: 46
- Joined: Wed Jun 17, 2020 3:26 am
Speed of later models
Indeed. The 8 Mhz limitation is due to various components on the board such as ROM, the sound chip, the Vera, etc. In fact, we only have it working stable at 4 Mhz at the moment on the latest rev of the proto-board. But, with a few minor changes we still fully expect to get it back up to 8 Mhz and stable.
Having said that, stage 2 and stage 3 do present the possibility to go faster. Specifically stage 3, which is all inside a single FPGA. We have a prototype of that which runs at 14 mhz and seems stable. But, as far as the DIP style board, which serves as the basis for the whole computer architecture, 8 Mhz will likely be all you will ever see.
Speed of later models
46 minutes ago, The 8-Bit Guy said:
stage 3, which is all inside a single FPGA. We have a prototype of that which runs at 14 mhz and seems stable
Oh my. That. Sounds. Awesome. I love and hate you right now. ?
Speed of later models
2 hours ago, The 8-Bit Guy said:
Indeed. The 8 Mhz limitation is due to various components on the board such as ROM, the sound chip, the Vera, etc. In fact, we only have it working stable at 4 Mhz at the moment on the latest rev of the proto-board. But, with a few minor changes we still fully expect to get it back up to 8 Mhz and stable.
Having said that, stage 2 and stage 3 do present the possibility to go faster. Specifically stage 3, which is all inside a single FPGA. We have a prototype of that which runs at 14 mhz and seems stable. But, as far as the DIP style board, which serves as the basis for the whole computer architecture, 8 Mhz will likely be all you will ever see.
Aha, hence "enhanced", a "turbo" mode, a la the original IBM PC and the IBM XT.
But it's phase 2 I have my eye on, and I'm more hoping that it has the real sound chip than worrying about it's clock speed. I can buy heaps of Chinese portable game consoles with much faster clock speeds than the CX16p for well under $100 ... but I am not interested in doing much programming on them.
Speed of later models
4 hours ago, The 8-Bit Guy said:
Indeed. The 8 Mhz limitation is due to various components on the board such as ROM, the sound chip, the Vera, etc. In fact, we only have it working stable at 4 Mhz at the moment on the latest rev of the proto-board. But, with a few minor changes we still fully expect to get it back up to 8 Mhz and stable.
Having said that, stage 2 and stage 3 do present the possibility to go faster. Specifically stage 3, which is all inside a single FPGA. We have a prototype of that which runs at 14 mhz and seems stable. But, as far as the DIP style board, which serves as the basis for the whole computer architecture, 8 Mhz will likely be all you will ever see.
I should mention that Gideon has managed to get the Ultimate 64 running at 48MHz. So it's definitely possible to run the 6502 at that speed; although I'm not sure precisely how he manages the CIAs and other forms of I/O, though.
If the U64 only had an 80-column output....
Speed of later models
5 hours ago, TomXP411 said:
I should mention that Gideon has managed to get the Ultimate 64 running at 48MHz. So it's definitely possible to run the 6502 at that speed; although I'm not sure precisely how he manages the CIAs and other forms of I/O, though.
If the U64 only had an 80-column output....
Looking at reviews and photos on the Ultimate 64, it looks to me like the U64 eschews physical instances of the typical supporting 65XX chips. Presumably any I/O support is part of the FPGA. There are sockets for physical SID chips, but I suppose they can use variable clock speed to interface with those if installed. From what I've read on 6502.org, it gets a lot easier to achieve stable faster clock speeds when most of the system is on a single chip.
Speed of later models
Not had much input into these things but it seems that at the very least the phase 2 and 3 versions should have the same speed (if not all of them). If you don't you end up with the issue that the original systems had which is that when making software you will always end up aiming for the lowest common denominator. Even worst if someone writes software that is CPU speed dependent (I guess you would need a Turbo button :))
Speed of later models
1 hour ago, Cunnah said:
Not had much input into these things but it seems that at the very least the phase 2 and 3 versions should have the same speed (if not all of them). If you don't you end up with the issue that the original systems had which is that when making software you will always end up aiming for the lowest common denominator. Even worst if someone writes software that is CPU speed dependent (I guess you would need a Turbo button :))
The present prototype board is wired to be selectable between 2, 4 and 8MHz ... that's what the reference to only booting it up stable at 4MHz at the present is. So, eg, a jumper to select between 8MHz and 12MHz in phase 3 (CX16"e") shouldn't not be TOO difficult.
Speed of later models
2 hours ago, BruceMcF said:
The present prototype board is wired to be selectable between 2, 4 and 8MHz ... that's what the reference to only booting it up stable at 4MHz at the present is. So, eg, a jumper to select between 8MHz and 12MHz in phase 3 (CX16"e") shouldn't not be TOO difficult.
That makes sense (and I recall that being the case from the previous videos) I guess it needs to be locked down for the later revisions if the intention is to avoid devices competing with each other and a split software base (or more likely an unused potential)
Speed of later models
15 hours ago, Cunnah said:
That makes sense (and I recall that being the case from the previous videos) I guess it needs to be locked down for the later revisions if the intention is to avoid devices competing with each other and a split software base (or more likely an unused potential)
Well, hopefully the CX16P and CX16C have the same hardware constraints on their ASIC chip timings, which would imply the same speed constraint. The only one where that hardware constraint would not be the same would be the CX16E. So a common speed for all three and a single "turbo" mode option for the CX16E is what makes sense for me.
Mind, it's not my call, and I'm not worried about the design team making a real blunder, so I'm not going to fret about it.
Speed of later models
Now I wonder how many 6502's one could cram onto a single die using modern 14nm and smaller transistor sizes.