ZX81plus38 simple to build ZX-81 clone

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Project ZX81plus38
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Most people I showed my ZX-81 clone (ZX81+35) said they liked it, but with such a tiny board and with so many "difficult" surface mount components, they they doubted whether they would be able to build this kit, so I restarted my effort.
Status Initializing
Contact mahjongg
Last Update 2019-09-18


September 18, 2019 I started

For now I will call it ZX81+38, but I doubt it will be finished in 2019, so it will probably be renamed to ZX81plus39... :-)

I started analysing my current schematic, to see whether it contains components that are not available in PTH, and unfortunately there are some, for example "unbuffered inverters" (74HCU04) is no longer available in DIP. Also SOME other logic isn't available in DIP, 13MHz crystals are hard to get in PTH versions, and 6.5MHz are no available at all. I decided to switch from 128K flash ROM to 32K OPT ROM's because the latter are available in DIP-28. I also found cheaper 32K x 8 static RAM also in DIP_28, which wil be easier to use.

I'll design it with KiCad unlike te older version which was designed using Ulticap and Ultiboard.

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