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2022-06-23 17:39:06 +02:00
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@@ -30,3 +30,5 @@ The BOM contains exact component designators for all components used from either
Note that R21 (the series resistor for a keyboard LED )is NOT in this BOM, as I added it after I created the BOM, but should be 330 Ohm (if you add a keyboard LED) That is if you built the keyboard I designed for the ZX81plus35 that also works with this ZX81plus38, in the schamatic a value of 100Ohm is used, which is also okay, although much brighter.
on june 15, 2022 I uploaded a BOM for revision 1.6 of the ZX81+38 creating some corrections R20 should be 680R, R21 should be 330 R R29 should be 1M RP22 can be 10Kx8 but 22Kx8 works better with some keyboards, C7 should be 47nF, most importantly U21 should be a 74HC04 or 74HCU04 NOT A 74HC14!
On June 23, 2022 I finished the schematic for a new revision 1.7 version of the ZX81+38 with several corrections. and also updated the layout. The main correction is the rotation of the keyboard-data connector J3, so the ZX81+38 is now completely compatible with a ZX-81 keyboard foil, other changes are that U21 is now a 74HC04 with R29 as an 1M resistor. JP1 is now default jumpered for a 16K ROM space, so its compatible with the future PSG board, and the firmware for the SD interface in a second 8K ROM section, if you don't want this (you want to use four 8K selectable ROM's) then switch over JP1. I made the crystal footpad now compatible for a SMD crystal too, and printed several texts on the sikscreen bootom and top to help with selecting options, and improve compatibility with the BOM.