The Hidden Front Panel of the IBM 5100

[Quadibloc]

Although no blinkenlights are provided, a very small amount of front bezel real
estate was needed...

The IBM 5100 had a switch, Registers/Normal, that changed its built in CRT from
displaying the dialog between the user and the program running to displaying the
CPU's internal registers.

This might make it the last well-known computer to have some sort of provision for
viewing the processor's registers like that...

John Savard

[Oregonian Haruspex]

My HP41 can do that too.

[Christian Corti]

Post by Quadibloc
The IBM 5100 had a switch, Registers/Normal, that changed its built in CRT from
displaying the dialog between the user and the program running to displaying the
CPU's internal registers.

To be more precise, it's only a coincidence that you can see the
internal registers. Technically, you see the first 512 bytes of the RWS,
but the registers are memory mapped (16 words for each IL, 64 words total)
at X'0000, they are implemented separately on the CPU card with two 64x9
bit TTL RAMs.

Christian