IBM 5170 - Cassette BASIC
This is the BASIC that is built into the IBM 5170 motherboard.
The 5170 motherboard will boot to cassette BASIC if it cannot find a disk that it can boot from.
On the 5170 motherboard, it resides together with the BIOS in chips U27 and U47.
Yes, this is pretty much the same 'cassette BASIC' found in the 5170's predecessors, the IBM 5150 and IBM 5160. And it has the same limitation of not being able to write/read BASIC files to/from floppy disks (or hard disk drives). If you require disk support, then use the BASIC or BASICA included in IBM PC DOS.
When cassette BASIC starts, one of the things displayed is the version number.
In a 5170, it will be version C1.10
The 'C' portion is an indicator that the BASIC is the 'cassette' version.
Although cassette BASIC runs from ROM, it uses RAM (to hold your program, for variables, etc.)
If cassette BASIC is run, it uses 64 KB of whatever RAM is fitted in your 5170.
In the Guide to Operations manuals for the 5170, IBM do not use 'cassette BASIC'. IBM BASIC is used instead.
In the 5170 Technical Reference manuals, 'cassette BASIC' and 'resident BASIC' are used.