μKenbak-1 Data Lights Toggle?

[Tom Lake]

On the μKenbak-1 repeated pressing of the data switches 0 - 7 will toggle the data lights on and off. In the JavaScript emulator at 

Kenbak-1 JS

once a data light is on, the only way to turn it off manually is to press CLEAR. Which is the correct behavior for an authentic Kenbak-1?

In reading the manuals, the JS emulator seems correct since EX 1-4 in the lab exercises book says, "If you make a mistake, use Clear to erase all of the 1's and try again." so it seems like once you press a data button, the data should stay at 1,

[Frank P.]

Mark Wilson's emulator defaults to allowing you to toggle the lights, but in case you want it to work just like the original Kenbak-1, he included a way to make that happen. If you execute a SYSX instruction (0360) with 0210 in the A register and 0 in the B register, it will change the behavior such that you must use CLEAR. If you repeat that instruction but with 1 in the B register, the toggling behavior is restored. Here is the relevant paragraph from Mark's emulator documentation:

010: Flags controlling the Kenbak-uino. 

Currently only 1, if b0 is set, pressing one of the Data switches *toggles* 

the bit, otherwise it only sets it (as per the KENBAK-1).

Here's the code (starting from 0):

210

000 [change to 1 to enable toggle]

000

004

360

000

343

004

[Michael Uhlmann]

thank you, that was I looking for!

[Vicente González]

I frequently use manual mode to change the behavior of the data switches.

Kenbak-uino Flags (System Register 10 in octal).
010: Flags to control the Kenbak-uino. There is only one flag (bit-0).
     If b0 == 1 the Data-switch "toggles" the Data-bit.(default state)
     If b0 == 0 the Data-switch "sets" the Data-bit (original KENBAK-1).

The content of this register can be read or write using STOP+READ or STOP+STORE
    1.- Set the Flags register address (010) using the Input register (Data Leds) and pressing  SET (ADDRESS).
    2.- Then after putting (001) for "toggle mode" or (000) For "set mode" in the Input Register, press STOP+STORE.

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