Speed
¼× Original 4× 16×
Sound
Sound off
Port 4 = 0: silent
The second option is the wiring of the manual's melody generator (listing 40); it is switched on when that program is loaded, and off otherwise because Port 2 idles with all lines on. Instruction 23 (P4A) switches the Port 4 tone: 0 (and 255, the switch-on value) is silence, 1 is middle C, and each step up is a semitone higher.
Ports
The module above the computer has eight LEDs for Port 2 (outputs) and eight switches for Port 1 (inputs). Line 1 counts 1, line 2 counts 2, line 3 counts 4, and so on up to 128.
Ground rail and contact clips (manual section 1.53): a clip on a Port 1 terminal is a push button — hold it and that line reads 0. Clips fitted on lines:
Click a clip on the machine, or hold Shift +1 …8 . Switches stay put; clips spring back.
Port 2 lines 1–8 go to Port 1 lines:
Inside
Program counter 000 Entry pointer 000
Red line: the program counter, where RUN and STEP continue. Blue line: the entry pointer (Eingabezeiger), where INP stores and OUT reads. Click a line to edit that cell (5 digits: 2 for the instruction, 3 for the operand).
Keys
PC keyboard: 0 –9 digits · Enter /I INP · O OUT · P PC · A ACC · R RUN · . /H STP · T STEP · Delete /X CLR · L CAL · S CAS · Esc power off/on.
Enter a program: type an address and INP (e.g. 0 0 0 INP ), then five digits and INP per instruction — two for the instruction, three for the operand. Start it with the address, PC , then RUN . STP stops it, ACC shows the accumulator, an address and OUT shows a cell, 9 OUT shows where the next INP will store.
Programmer's guide
Instructions: 01 HLT · 02 ANZ show · 03 VZG wait ms · 04 AKO load constant · 05 LDA load cell · 06 ABS store · 07 ADD · 08 SUB · 09 SPU jump · 10 VGL = · 11 SPB jump if true · 12 VGR > · 13 VKL < · 14 NEG · 15 UND · 16 P1E port 1 in · 17 P1A port 1 out · 18 P2A port 2 out · 23 P4A port 4 out (tone) · 19 LIA load indirect · 20 AIS store indirect · 21 SIU jump indirect.