Connect an EPROM with 4289

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Mizutsuki Raki



Joined: 23 Mar 2014
Posts: 59
Location: Seoul, Korea

PostPosted: Fri Jan 02, 2015 10:48 am    Post subject: Connect an EPROM with 4289 Reply with quote

Hello, I'm going the design the 4004/4040 testboard in a simple way. Using 4201 clock generator and less components.
But I found there's two method to connect an EPROM with 4289.

In picture resister_absent, I have seen this method normally. That is, an EPROM directly connected to 4289.
But some people added resisters on EPROM's data bus. Like resister_present picture.

What's the difference? I think it's the difference of push-pull and open drain.
http://www.cpu-galaxy.at/cpu/Ram%20Rom%20Eprom/ROM/Intel%202716%20section-Dateien/2716_Datasheet.pdf
Unfortunately, I'm new in this. I'm going to use 2716 UVEPROM. And I can't find whether the 2716 is push-pull or not. I need some help please.

Thanks a lot.
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lhf_james



Joined: 17 Oct 2008
Posts: 337
Location: Nanjing China

PostPosted: Fri Jan 02, 2015 11:46 am    Post subject: Reply with quote

I didn't add the pull-up resistors on my testboard mainly because space constrains, and the circuit works without problem. I also used the oscilloscope to check the data lines and the slew rate looks great. So there's actually no need to add these resistors I think, and 2716 isn't open drain actually. Some circuits add the resistors just to increase the stability.
I also checked my collection and found a board made by rockwell that was used on Boeing aeroplanes. It has C2708 directly connected to D4289, without pull up, and should (of course) work fine Wink

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Mizutsuki Raki



Joined: 23 Mar 2014
Posts: 59
Location: Seoul, Korea

PostPosted: Fri Jan 02, 2015 12:13 pm    Post subject: Reply with quote

Oh, many thanks.
I'll share the schematic when I complete a testboard.
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