dk'Tronics memory expansions - different types?

Started by Ygdrazil, 23:56, 09 September 09

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Ygdrazil

dk'tronics made at least three types of memory expansions for the CPC!

a 64Kb version intended for the CPC464 to make it up to date with the CPC6128

a 256Kb expansion for the CPC6128

and

and the Silicon Disk always with the capacity of 256Kb!

Is this correct or did there exist other version's then the above 3????

/Ygdrazil

Ynot.zer0

>a 256Kb expansion for the CPC6128

Interesting, I have one of these but didn't realise it was 6128 only.... I'll re-test it on a 464 / 664 this weekend


arnoldemu

Quote from: Ygdrazil on 23:56, 09 September 09
dk'tronics made at least three types of memory expansions for the CPC!

a 64Kb version intended for the CPC464 to make it up to date with the CPC6128

a 256Kb expansion for the CPC6128

and

and the Silicon Disk always with the capacity of 256Kb!

Is this correct or did there exist other version's then the above 3????

/Ygdrazil
I think I saw a 64k silicon disk in amstrad action or acu magazine.
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Cholo

Ive got a genuine dk'tronics 256k ram expansion for 464 (small one unlike the 6128 longer ones). So those was made too  ;)

Gryzor

Why would there be different versions for the 464/6128??

Devilmarkus

Quote from: Gryzor on 08:04, 11 September 09
Why would there be different versions for the 464/6128??

Thats logical:
The 6128 already has a 2nd ram bank with 64k , the 464 not.

Also: The German CPC 6128 has centronics-connectors.
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Gryzor

Yes, but it's a 256KB extension, or an extension to 256kb?

Axelay

As I understand it from the article on ram paging on Kevin Thackers' site, the 6128s internal extra 64k would be unavailable when an external ram expansion is used as the ram manager in the expansion takes over.


So I'd wonder if perhaps the 464 & 6128 didn't have their own 256k expansions simply because the systems were a different shape at the back, and the edge connectors at different heights from the bottom.

Octoate

Quote from: Gryzor on 08:04, 11 September 09
Why would there be different versions for the 464/6128??
The 6128 already contains the banking logic in the Gate Array. The 464 doesn't and so you have to add extra logic for that.
--

arnoldemu

Quote from: Octoate on 14:42, 11 September 09
The 6128 already contains the banking logic in the Gate Array. The 464 doesn't and so you have to add extra logic for that.
Well, the PAL is seperate to the Gate-Array and this controls the banking.

But I still think that all the ram expansions will require their own PAL, because the PAL inside the CPC6128 can't access external memory and is effectively hardwired to the internal 128K ram.

I think the only difference between 464 and 6128 versions is the case design, so that the device fits to the back of the computer without it moving and being unstable on the connector.

So you could easily put a 64k ram expansion onto a 6128, although it would effectively be useless because you already have 64k extra ram inside cpc6128 so you will not be adding anything ... and then it comes down to which actually has priority; my guess is the external ram over the cpc6128's extra ram but I have not confirmed this.
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Cholo

#10
If you look in pretty much any old copy of "Computing with the Amstrad" at the center pages youll see the double page dk'tronics commercial for both 464 and 6128 expansions.

The top pictures are the slimmer but longer 6128 versions and the ones below are the 464 smaller but chunkier ones. A bit odd really is that there is a 64k in the picture for 6128. As someone mentioned, adding a ram expansion to a 6128 "replaces" the internal extra 64k. Like if you add a 512k rambox all you get is the 64k+512k in all. So adding a 64k expansion dosnt really make sense (unless the dk'tronic one is special .. and was actually made).

As to why there is both a 464 and 6128 version of the expansion, id say it was quite logical at the time. Basicly i think everyone at the time was using the same strategy as IBM (Back then only IBM hardware would run in a IBM pc .. unlike today where you can use any brand). Same reason i think Amstrad chose the odd 3" discs over the 5,25" and 3,5" ones .. to "force" people to buy from you direct. Having 2 versions of the hardware ensured that you need to buy both versions if you got both a 464 and 6128.

Gryzor

Well, as soon as I read your first sentence I remembered the contour differences in the machines' case. I think this was a valid enough reason for them to produce two models anyhow... :D

zhulien

464 RAM expansion and silicon disk variations work 100% on CPC6128 (we usually used these plugged behind a ribbon cable or expansion such as hack-it)

Bryce

Hi,
   the only difference between the 464 and 6128 versions of the expansion was the casing and the layout of the PCB. The reason for this was as suggested above, due to the different casing of the two machines. The edge connector on the english version of the CPC was very unreliable if the expansion wasn't resting on the desk and unfortunately the edge connector had a different height (slightly higher) from the desk on the 464. There was a 64K and 256K available for both the 464 and 6128. The 64K version for the 6128 added 64K to the 128K (ie: a total of 192K) however the 256K version added only 192K to a 6128, not because it "over-wrote" the internal 64K, but because the banks of 16K were numbered 0 to 15 (16x 16K) and because of this, the top banks within the expansion were not normally accessible without some trickery (poking the value 1 to the address 10006 let the user choose up to 32 Banks).

There was also a 64K and 256K Silicon Disk for both machines, although they were technically very similar to the expansion packs, they were not simply banks of RAMs and couldn't be addressed as such or switched in and out as such. The hardware emulated a disc-drive and could only be used to mirror a disk for faster access than a real disc.

Has that answered everything asked?

Bryce

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