@cstanhope Nothing comes to mind right now, except that you had to have permission from them to be an officially licensed developer for those platforms. IIRC, TI in particular would viciously go after anyone who made software for the platform and sold it for profit without having a license. Tandy didn't much care so much, but you couldn't put Tandy/Radio Shack logo on your box without that license, and they'd not be sold through the Radio Shack stores.
@cstanhope Ahh, https://en.wikipedia.org/wiki/Texas_Instruments_TI-99/4A#Lack_of_third-party_development discusses TI's rationale a bit.
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