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2026-05-28T06:32:57Z

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{{FormatInfo
|subcat=Error detection and correction
|released=1983-01
}}
'''Rainbow Chek''' (RBOWCHEK) by Dennis S. Lewandowski is a type-in program checker for Tandy TRS-80 Color Computer (CoCo) by The Rainbow Magazine.

'''Rainbow Check Plus''' by H Allen Curtis is a significant upgrade that adds support for the MC-10 and 4K CoCos.

Jerry Stratton wrote RCHECK+ in Perl and rcheck+ for macOS so that programs could be entered on modern computers.

The first version only supported the 16K and 32K variants and simply counted up the number of (crunched) bytes in the program, presenting the total in hex.

These totals were only provided after a group of lines, so they didn't specify which exact line had the problem.

Rainbow Check Plus has a running total of the value of all characters up to 255 (decimal) before rolling over. It catches far more errors than the original Rainbow Chek but still misses transposition errors.

== Sample Output ==
[[File:Rainbow_Chek.jpg]] Rainbow Chek

[[File:Rainbow_Check_Plus.jpg]] Combined Rainbow Chek and Rainbow Check Plus listing

== Links ==
* [https://archive.org/details/rainbowmagazine-1983-01/page/n93/mode/2up Rainbow Chek] (The Rainbow Magazine Jan 1983 pg 95)
* [https://archive.org/details/198402Rainbow/page/20/mode/2up Rainbow Check Plus] (The Rainbow Magazine Feb 1984 pg 21)
* [https://www.hoboes.com/Mimsy/hacks/coco/rcheck-plus/ RCHECK+ in Perl and rcheck+ for MacOS]
* [https://www.hoboes.com/Mimsy/hacks/coco/typing/ Thoughts on typing 8-bit code]
* [https://www.youtube.com/watch?v=YRwQyLVAUqs The clever way Rainbow Magazine "solved" BASIC typos for CoCo]
* [https://cocotownretro.wordpress.com/2026/05/27/rainbow-magazines-check-plus-solves-typos/ Rainbow Magazine's CHECK PLUS "solves typos"]
* [https://github.com/cocotownretro/VideoCompanionCode/tree/main/RainbowCheck .BAS files for Rainbow Chek and Rainbow Check Plus, disassemly and commentary of Rainbow Check plus]
* [https://subethasoftware.com/2025/02/22/rainbow-check-plus/ Rainbow Check and Rainbow Check Plus at Sub-Etha Software]

Rainbow Chek/Rainbow Check Plus - Revision history

Parchivist: Created page with "{{FormatInfo |subcat=Error detection and correction |released=1983-01 }} '''Rainbow Chek''' (RBOWCHEK) by Dennis S. Lewandowski is a type-in program checker for Tandy TRS-80 C..."