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RE: [N8VEM-S100:4466] Re: ALTAIR/IMSAI 8080 CPU replacement board

Hi Group,

I've been having some trouble with the level shifter between the SD card and the 74LS299 Shift Register.

On advice from a friend, he suggested I just route the 3.3V signal directly into the 74LS chip.  Apparently, this is how it's done on the Arduino shield.  I did this and it works perfectly.  This mod requires 1 cut trace, and 1 jumper.

I have updated the schematic with various IC,  resistor and capacitor values
It also has the mod described and shown.

I am presently working on the BIOS and a manual for this board that should include the BOM and this recent MOD.

Please find the latest schematic on the share site at:

Josh Bensadon