What kind of RAM speed for APPLE 1?

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asbesto's picture
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Joined: Aug 22 2012
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Hi there,

I saw many kind of MOSTEK ram chips like 4027N-1 or 4027N-3 or 4096-11... I think the last digit is the speed. Does someone know if they all work on the ALLPE 1, due to his low working speed?

Thank you,
Gabriele

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73 de IW9HGS - Gabriele "Asbesto" Zaverio"
Director of "Museo dell'Informatica Funzionante" Computer Museum
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asbesto's picture
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Re: What kind of RAM speed for APPLE 1?

I also found some TMS-4027-30 or ITT 4027-6J memories... will they work? Smile

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73 de IW9HGS - Gabriele "Asbesto" Zaverio"
Director of "Museo dell'Informatica Funzionante" Computer Museum
http://museum.freaknet.org - Palazzolo Acreide (SR) - Italy

speedyG's picture
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Re: What kind of RAM speed for APPLE 1?

Hello asbesto,
not all extensions clearly indicate the speed.... common endings like -1 or -2 or -3 do so.
-1 is = 100 nS, -2 = 200 nS and -3 = 300 nS.
usualy you should use for the apple1 rebuild the Mostek MK4096 which is also indicated by the circuitplan of the apple 1
( see apple 1 manual ) and the common used chips were -2 or 200 nanoseconds... -3 probably are to slow and can cause errors by to slow timing.... ROMs have other timing and therefor may be slower --- up to maximum of 350 nanoseconds...
sincerely speedyG

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Joined: Jun 5 2008
Posts: 381
Re: What kind of RAM speed for APPLE 1?

Most original units were populated with MOSTEK 4096-11. Those are the slowest of the MOSTEK chips of that era - 350ns access time and 500 ns cycle time and 320mW power consumption.

Faster parts may work, but be aware that they draw more power and there is marginal power distribution, especially to the DRAM on the Apple 1 motherboard. I vaguely remember someone telling me that they tried MK4027s and they worked.

Regards,
MIke Wilelgal