Prior to the Unicode era, the following Harvard-Kyoto scheme was developed for putting a fairly large amount of Sanskrit textual material into machine readable format without the use of diacritics as used in IAST. Instead of diacritics it uses upper case letters. Since it employs both upper and lower case letters in its scheme, proper nouns' first letter capitalization format cannot be followed. Because it is without diacritics, it enables one to input texts with a minimum motion of the fingers on the keyboard. For the consonants, the differences to learn are: compared to IAST, all letters with an underdot are typed as the same letter capitalized; guttural and palatal nasals (ṅ, ñ) as the corresponding upper case voiced plosives (G, J); IAST ḷ, ḻ, ḻh are quite rare; the only transliteration that needs to be remembered is z for ś. The vowels table, the significant difference is for the sonorants and Anusvāra, visarga are capitalized instead of their diacritics. Finally, it is fairly readable with practice.
Sanskrit text encoded in the Harvard-Kyoto convention can be unambiguously converted to Devanāgarī, with two exceptions: Harvard-Kyoto does not distinguish अइ (a followed by i, in separate syllables, i.e. in hiatus) from ऐ (the diphthong ai) or अउ (a followed by u) from औ (the diphthong au). However such a vowel hiatus extremely rarely would occur inside words. Such a hiatus most often occurs in sandhi between two words (e.g. a sandhi of a word ending in 'aH' and one beginning with 'i' or 'u'). Since in such a situation a text transliterated in Harvard-Kyoto would introduce a space between the 'a' and 'i' (or 'a' and 'u') no ambiguity would result.
^Aksharamukha transliteration tool. Akshara Mukha is an Asian script (two way) converter. It converts between 20 different South Asian & East Asian scripts. It also supports 5 major Latin transliteration conventions such as IAST, ISO, Harvard Kyoto, ITRANS & Velthuis. You can access the project from here. While using the tool, 'source' can be set to for example: ITRANS or Harvard-Kyoto, and 'target' can be set to a particular script like Devanagari-Hindi.(When you are using a north Indian script, tick the box: Remove ‘a’.) It can work in reverse too, for example from Hindi to Latin by ISO transliteration.