CURRENT PROTOTYPE STATUS (SEC 64MHz 68000)

Information and news about the 68SEC000 64MHz booster.
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exxos
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Re: V2.5 BOOSTER CURRENT PROTOTYPE STATUS (SEC BOOSTER)

Post by exxos »

Forgottenmyname wrote: Mon Feb 04, 2019 11:57 am Well done Exxos
:thanksyellow:

I need to find a 55MHz osc somehow now :lol:

Hopefully this now (finally!) marks the end of my 68000 booster research :)
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Re: V2.5 BOOSTER CURRENT PROTOTYPE STATUS (SEC BOOSTER)

Post by PhilC »

Got a 233mhz one if you wanna try it :D
If it ain't broke, test it to Destruction.
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Re: V2.5 BOOSTER CURRENT PROTOTYPE STATUS (SEC BOOSTER)

Post by exxos »

A while ago I was working on the fast RAM version...

https://www.exxosforum.co.uk/forum/viewt ... q-Y#p14194

Which was actually a huge waste of time, as I now had to do a lot of design changes the current SEC booster :roll:

So I have added back on the fast ram onto the modified board, along with flash.

I did have ROM on the previous board, but as flash is on the board, and can be used externally with ROM anyway, there is little use in adding it to this board. It will also make fitting the board in the STFM actually fit without in the way of the MMU.

So this will keep me busy for a while..

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Re: V2.5 BOOSTER CURRENT PROTOTYPE STATUS (SEC BOOSTER)

Post by rubber_jonnie »

You know, you could skip 55Mhz and go straight for 60......
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800XL and 65XE both with Ultimate1MB,VBXL/XE & PokeyMax, SIDE3, SDrive Max, 2x 1010 cassette, 2x 1050 one with Happy mod, 3x 2600 Jr, 7800 and Lynx II
Approx 20 STs, including a 520 STM, 520 STFMs, 3x Mega ST, MSTE & 2x 32 Mhz boosted STEs
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Re: V2.5 BOOSTER CURRENT PROTOTYPE STATUS (SEC BOOSTER)

Post by exxos »

rubber_jonnie wrote: Mon Feb 04, 2019 2:09 pm You know, you could skip 55Mhz and go straight for 60......
From tests before it maxed out at 58MHz. There doesn't seem to be any oscs around in that range though :( Next jump seems to be 64.
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viewtopic.php?f=17&t=1585 Have you done the Mandatory Fixes ?
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Re: V2.5 BOOSTER CURRENT PROTOTYPE STATUS (SEC BOOSTER)

Post by rubber_jonnie »

exxos wrote: Mon Feb 04, 2019 2:12 pm
rubber_jonnie wrote: Mon Feb 04, 2019 2:09 pm You know, you could skip 55Mhz and go straight for 60......
From tests before it maxed out at 58MHz. There doesn't seem to be any oscs around in that range though :( Next jump seems to be 64.
64 it is then ;)

I guess there will be a logical point at which the CPUs can't be overclocked anymore. Would be very cool if it could be switched in software.
Collector of many retro things!
800XL and 65XE both with Ultimate1MB,VBXL/XE & PokeyMax, SIDE3, SDrive Max, 2x 1010 cassette, 2x 1050 one with Happy mod, 3x 2600 Jr, 7800 and Lynx II
Approx 20 STs, including a 520 STM, 520 STFMs, 3x Mega ST, MSTE & 2x 32 Mhz boosted STEs
Plus the rest, totalling around 50 machines including a QL, 3x BBC Model B, Electron, Spectrums, ZX81 etc...
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Re: V2.5 BOOSTER CURRENT PROTOTYPE STATUS (SEC BOOSTER)

Post by exxos »

rubber_jonnie wrote: Mon Feb 04, 2019 2:19 pm 64 it is then ;)
If I can find the OSC I will try it again, but doubt it will work.
rubber_jonnie wrote: Mon Feb 04, 2019 2:19 pm Would be very cool if it could be switched in software.
It is on the "to do list" but I am having issues with realtime clock switching on this board. So even switching speeds with the power on isn't going to be possible for a while. I will investigate it eventually, but I want to get on with something else like the fast-ram and flash-rom.
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viewtopic.php?f=17&t=1585 Have you done the Mandatory Fixes ?
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Re: V2.5 BOOSTER CURRENT PROTOTYPE STATUS (SEC BOOSTER)

Post by rubber_jonnie »

exxos wrote: Mon Feb 04, 2019 2:29 pm
It is on the "to do list" but I am having issues with realtime clock switching on this board. So even switching speeds with the power on isn't going to be possible for a while. I will investigate it eventually, but I want to get on with something else like the fast-ram and flash-rom.
I can understand, makes sense to get the other stuff in place, that will make a big difference.
Collector of many retro things!
800XL and 65XE both with Ultimate1MB,VBXL/XE & PokeyMax, SIDE3, SDrive Max, 2x 1010 cassette, 2x 1050 one with Happy mod, 3x 2600 Jr, 7800 and Lynx II
Approx 20 STs, including a 520 STM, 520 STFMs, 3x Mega ST, MSTE & 2x 32 Mhz boosted STEs
Plus the rest, totalling around 50 machines including a QL, 3x BBC Model B, Electron, Spectrums, ZX81 etc...
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Re: V2.5 BOOSTER CURRENT PROTOTYPE STATUS (SEC BOOSTER)

Post by exxos »

rubber_jonnie wrote: Mon Feb 04, 2019 2:48 pm I can understand, makes sense to get the other stuff in place, that will make a big difference.

I tried 64MHz.. Basically nope.. bombs on 104, 206 doesn't even try. I added in some more delays, but nope...

If I remember rightly, during my last tests, what I did was to literally just run the CPU faster on integer division test. I think it would basically lock up halfway through the test each time.

It may not necessarily be the CPU cannot run that fast, but the bus itself probably isn't anywhere near stable enough for it. Of course I already hit issues with 50MHz :(

Even so, even 50MHz is probably way too fast. Look at it that how fast they cycle is now, basically 20ns.

Even adding fast ram would mean we would need 10ns RAM which is hard to find and incredibly expensive.

I think talked about this previously that I was considering using a small bank of fast ram (10ns) to copy the ROM contents to during start-up. This is because the flash and ROM chips are basically too slow by themselves. So even adding flash is going to slow ROM access down.

In terms of fast ram, I think we will be pushed to even get 60ns RAM access speed. Which basically equates to 32MHz speeds. Realistically 32MHz would be a much better point to operate at.

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Re: V2.5 BOOSTER CURRENT PROTOTYPE STATUS (SEC BOOSTER)

Post by rubber_jonnie »

It would make sense that the bus and maybe other components may not be happy when pushing way beyond the original 8Mhz speed.

I have to take my hat off to you that you've got so far with this.

:bravo:
Collector of many retro things!
800XL and 65XE both with Ultimate1MB,VBXL/XE & PokeyMax, SIDE3, SDrive Max, 2x 1010 cassette, 2x 1050 one with Happy mod, 3x 2600 Jr, 7800 and Lynx II
Approx 20 STs, including a 520 STM, 520 STFMs, 3x Mega ST, MSTE & 2x 32 Mhz boosted STEs
Plus the rest, totalling around 50 machines including a QL, 3x BBC Model B, Electron, Spectrums, ZX81 etc...
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