troed wrote:I have just piggy-back upgraded a 520ST using memory chips I've carelessly hot-aired out from other ST machines, and predictably some of the chips have faults. During the hunt to find out which, I realized it would be nice to be able to force a RAM test program like this to test a specific memory size/range even though TOS hasn't detected it
(Since my bank 1 has errors TOS initializes to 512KB)
No one reads the included documentation anymore...

Quoting from it: "YAARTTT.TOS has a "hidden feature": Pressing 'M' at the prompt right
after startup will switch to manual address entry mode. You can then
enter any start and end address, e.g. to test memory that is not
registered with GEMDOS. However, testing allocated or non-existing
memory will crash the system or cause data corruption!"
PS: Even though it's call YAARTTT, it'll run on your ST.