Author Topic: [NC Series] Dreamwriter 225, The missing link  (Read 5545 times)

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Offline Gryzor

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Re: [NC Series] Dreamwriter 225, The missing link
« Reply #25 on: 20:55, 17 September 13 »
Thanks for the pics! :)

Offline TFM

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Re: [NC Series] Dreamwriter 225, The missing link
« Reply #26 on: 22:57, 17 September 13 »
Yepp, MaV's avatar is amazing  ;)
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Offline MaV

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Re: [NC Series] Dreamwriter 225, The missing link
« Reply #27 on: 17:08, 18 September 13 »
Interresting idea. What would be the advantage of the V20 over the 6 MHz Z80? Is it pricing?
Hm, that would need a profound comparison of the two chips.
I don't have any data on pricing, and 80's/early 90's data on pricing is probably impossible to get these days.

Much like the 8088, the V20's basic instructions take as few as two cycles (8088 min. 3 cycles?), but as soon as memory is addressed the cycle count takes a leap. It also has block- and test/bit/set-instructions. An 8088 can beat a Z80, and the V20 is ~30% faster than an 8088.
Unfortunately, I've not found any infos on the instruction cycles for the 8080 mode.

Quote
Well, I can't imagine that they wrote the ROM new for another CPU, that would be a major task. So the 8080 mode seems not to be too far out of reality  :)
On the other hand, the 8088 - and therefore V20 - has an equivalent instruction for any single 8080 instruction, so converting the ROM assembly code might have been as easy as building a script and slightly modifying the result.

Besides, you have to take into consideration that the company's long term strategy might have been to change the architecture. Since all but the first model are V20 based, this seems to be the case. A one time conversion of the ROM looks feasible then.

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Offline MaV

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Re: [NC Series] Dreamwriter 225, The missing link
« Reply #28 on: 17:21, 18 September 13 »
Yepp, MaV's avatar is amazing  ;)
Hehe.

That is the picture of Luis de Góngora y Argote. A passage of one of his works is in my signature.

Translation:
"Because in a village a poor lad has stolen one egg
He swings in the sun and another gets away with a thousand crimes"


That is ever so true now as it was then.
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Offline TFM

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Re: [NC Series] Dreamwriter 225, The missing link
« Reply #29 on: 17:38, 18 September 13 »
An 8088 can beat a Z80

That remains to be prooven. I take the bet against evey 8088 coder here. The Z80 has a second register set, the 8088 not. I say the Z80 beats the 8088 when programmed right.  :)   8)   ;D  [nb]If I wouldn't say so, my life would end tragicly[/nb]
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Offline MaV

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Re: [NC Series] Dreamwriter 225, The missing link
« Reply #30 on: 14:01, 20 September 13 »
LOL! You need not fear for your life. ;) Yep, in a lot of cases you might be faster than an 8088, no doubt.

I wrote "can" on purpose.

The 8088 is a bit more complex to optimise for, because of the 4 byte prefetch queue. If it is empty - which happens when you have a string of fast operations - then you are down to the speed of fetching the commands from memory. A 2 clock cycle command then takes 4 cycles to execute, IIRC. So you need to rearrange the commands - if possible - to achieve better results.
Plus, a conventional CGA- or Hercules-graphics card inserts wait states, so you'll write and read slower to/from graphics memory.

This all is on top of my head, so take it with a grain of salt, until someone confirms or proves me incorrect.

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Offline robcfg

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Re: [NC Series] Dreamwriter 225, The missing link
« Reply #31 on: 21:55, 11 October 13 »
Hi guys!


I got a swedish NC100! Yep, swedish. I didn't knew that even existed, but goddess Fortuna guided me to it  :)


I've already dumped the rom, and it works flawlessly on MESS.


It's also available on the downloads section of the NC series page here at the CPCWiki.


Scans will be available during the weekend.


Cheers!

Offline Gryzor

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Re: [NC Series] Dreamwriter 225, The missing link
« Reply #32 on: 21:09, 12 October 13 »
Nice man, thanks :)

Offline SyX

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Re: [NC Series] Dreamwriter 225, The missing link
« Reply #33 on: 00:26, 26 October 13 »
With a lot of delay, but i'm here :)

Thanks robcfg!!! You always get the more sexy machines  :D ;)