RE: [N8VEM-S100:4500] Re: ALTAIR/IMSAI 8080 CPU replacement board -MOD

Hi Don & to All...

I put together a list and included it in the Manual. The Manual also covers the jumper settings, a block diagram, some verbage and the ECO change.

Please find the manual on the Wiki page
http://n8vem-sbc.pbworks.com/w/browse/#view=ViewFolder&param=S-100%20ALTAIR-IMSAI%208080%20CPU%20Board

I don't know about starting a "Build Page".

Regards,
Josh Bensadon

Date: Tue, 8 Jul 2014 10:17:25 -0700
Subject: Re: [N8VEM-S100:4500] Re: ALTAIR/IMSAI 8080 CPU replacement board -MOD
From: cap...@uxpro.com
To: n8vem...@googlegroups.com
CC: shum...@att.net

Josh,

Have you put together a bill-of-materials yet?

Is there a build page on the N8VEM wiki yet?

If not I can start one and add a BOM like I did for the backplane, complete with part

numbers for Mouser, digi-key.

On Tue, Jul 8, 2014 at 9:48 AM, Crusty OMO <crus...@hotmail.com> wrote:

Hi Group,

Some of you have recieved this board already. I wish to inform you that 1 mod is required.

I did not design the 3.3V to 5V circuit well enough and as it turns out, it's not really even needed.
The 3.3V data output of the SD Memory Card can be tied directly into the LS TTL input of the 74LS299 shift register.
One trace needs to be cut for this mod.

I am working on a manual for this board, I plan to publish it later today. But, for now, before you build, you might want to cut this trace.

The trace is on the component side, from pin 11 of the 74LS299 chip. Just below the silk screen text "SD LOOP BACK", there is the best place to cut it since there is ample space on either side. See photo attached.
A jumper wire then should then be placed between the resistor lead above the silk screen text "R7" to pin 11.

Regards,
Josh

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Don Caprio cap...@uxpro.com
http://www.uxpro.com
(925) 240-UNIX

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