CPC 464 prototype with Gate Array simulator board found

Started by balford, 13:58, 27 October 21

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rastislavz

Quote from: gerald on 18:14, 27 October 21However the SOLD AS SEEN UNTESTED (MAY NOT WORK) is a big showstopper for me.
I do not see that very tragic, thw guy is just scrap reseller so it does not know how and it does not want to test it, but the internals looks untouched, I think there is very high chance it may still work taking into account how sturdy these machines are in general. But I completely understand investing such huge ammount of money is quite risky.

rastislavz

#26
On Noels Retrolab discord I have offered him donation if he wins it. It would make a very nice video about it I am sure and would analyze it deeply. So if somebody else is willing to donate some money to him let him know on his discord.

Z|G

up $1500 pounds in less than 6 hrs (was $555 pounds, sitting @ $2000 pounds)....

any bets on where the price will finish up on  :D
1xCPC6128, 1xTandy Model 4, 1xC64 (IN BOX)

dragon

It have a  AM29705APC why they need ram?. .


Also it have lost one part of the board the part with the eeproms. (from the other eBay prototype).

gerald

Quote from: dragon on 20:49, 28 October 21
It have a  AM29705APC why they need ram?. .
It's  a 16 x 4bit dual port RAM. I guess it is used to store the ink configuration (but we miss 1 bit and the full border)
The ink / border registers are using about 70% of the gate array

Quote from: dragon on 20:49, 28 October 21
Also it have lost one part of the board the part with the eeproms. (from the other eBay prototype).
The EPROM side seems to be 4*2732 to emulate a 27128. Here we have a 27128 on the main board.



dragon

And in the left part they have hc chips and in the rest of the board ls chips.


I remember from the asignature of University(middle pc assembly/part of basic logic gates, karnaugh maps and  made a prototype board with her switch bus leds and so).


Don't mix hc and ls ics.. Don't mix hc and ls ics.


Well finally don't matter, we have a list of ics and in the shop.. oh I only have these in hc or I have only these in ls, or I don't have the but we have these another equivalent.



1024MAK

74LSxxx chips and 74HCxxx can be mixed, but with restrictions and limitations.

A 74HCxxx output pin can drive a 74LSxxx input without any problems.

74HCxxx use CMOS switching levels on their input pins, not TTL levels.

As 74LSxxx (and the earlier 74xxx, 74Sxxx) chips have TTL outputs, for any of these to drive a 74HCxxx, a pull-up resistor should be used. But a low value pull up resistor is needed for high speed operation, increasing power consumption. And this may not work at very high speeds due to stray capacitance.

Because of these problems, the 74HCTxxx range was introduced. These are still CMOS chips. They have the same outputs as 74HCxxx chips. But have inputs that are compatible with 74LSxxx outputs.

Mark
Looking forward to summer in Somerset :-)

retro_4_ever

£3092.00 wow !!!!! hope it ends up in noels retro lab ... 

TotO

I don't even want to imagine how much the final price would have been with the original keyboard and lower case, in working condition...  :laugh:
"You make one mistake in your life and the internet will never let you live it down" (Keith Goodyer)

retro_4_ever

how do you if the keyboard & case are not original ? should the bottom be grey as well ?
i did notice it was rated at 1.5amp on the bottom of the case, something i have not seen on any 464
and the keyboard was the same as the early productions models
when i first saw it i thought maybe £300 - £500 but 3K .. just wow !!!
i wonder how many of these were made and how many could still exist today


Bryce

As far as I know, the bottom of the prototype cases always had the dark grey colour. There was never a beige lower case.
Assuming normal prototype runs of the time for a device of this type, I'd guess there were probably 15 to 20 of these built.

Bryce.

dragon

I remember read about 50 in Google News. Probably same as software houses that program initially from the cpc.




And maybe exist some early prototype. In the spanish book of jose luis dominguez.  When he talk about how he promise to amstrad made poogaboo and Roland in the ropes. He talk that amstrad give it a computer that not appear a computer. He made in trouble in customs to explain thas was a computer, because was a mixture of wires. And appear pure trash.


These prototype appear a computer.


Gryzor


Bread80

Well, these were examples sent to software houses to create software on. So, I'd argue, more of a 'preproduction' model than a prototype.

Gryzor

Hmm an interesting point... In that light a prototype would be a wire board thing or in our case even the 6502 model

dragon

Quote from: Gryzor on 17:03, 31 October 21
I think Perry said 20?


You have lost the number "21" in the eBay computer. XD.


I'n the book is mentioned the even the ctm was a some type of strange prototype. Witouth frame.

 
https://groups.google.com/g/comp.sys.amstrad.8bit/c/QG-66_23rXY/m/JmVUNSlC7bMJ

Cliff Lawson write 50

TotO

Quote from: retro_4_ever on 17:53, 30 October 21
how do you if the keyboard & case are not original ? should the bottom be grey as well ?
i did notice it was rated at 1.5amp on the bottom of the case, something i have not seen on any 464
and the keyboard was the same as the early productions models
Because Roland Perry has said that. A shame to have replaced the original keyboard (gray keys like the tape buttons) with a new one. And the fact that prototypes CPC do not have hte metalic label under the case but a paper label.
"You make one mistake in your life and the internet will never let you live it down" (Keith Goodyer)

eto

Quote from: TotO on 21:14, 31 October 21And the fact that prototypes CPC do not have hte metalic label under the case but a paper label.


In a later discussion he acknowledged that "There must be two generations of grey 464 - because I've seen ones without the black label on the base.".

So the base might be from an original prototype.

TotO

I don't understand this sentence like an acknowledgment from him, but more the fact that he has only seen prototypes with paper label, so if this one is original, that mean there must be two generations of grey 464. I think that modern keyboard explain the back casing.
"You make one mistake in your life and the internet will never let you live it down" (Keith Goodyer)

dragon

If you come back to 2019 in Facebook group  Roland Perry upload the road of cpc 464 development.




The document tell hardware design mej


4-5 1st prototype


5-7 2nd-5nd prototypes


7-9 gate array cad


9-12 50 test units specify made.


So it appear they made five prototypes. Pre-gate array simulator board.


Bryce

Quote from: dragon on 05:00, 02 November 21
If you come back to 2019 in Facebook group  Roland Perry upload the road of cpc 464 development.




The document tell hardware design mej


4-5 1st prototype


5-7 2nd-5nd prototypes


7-9 gate array cad


9-12 50 test units specify made.


So it appear they made five prototypes. Pre-gate array simulator board.

That sounds like a completely normal development cycle for something like this.

Bryce.


Gryzor


Joseman

That Gate Array board, is the best option to clone de GA?

gerald

I have a working GA replacement, unfortunately component availability problem just can't make it happen ... yet  ;)
https://www.cpcwiki.eu/forum/amstrad-cpc-hardware/a-minimal-gate-array/msg198585/#msg198585

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