How is an instruction fetched in a processor?

Question

Electronic books

Hello! Please help me. In Petzold's book, k.o. e. The author first specifies, as a string, how the 3 byte instruction is stored in code memory. (e.g. 10h 00 00, "Load
byte at address 0000h into accumulator"). Here is the diagram and text: To make this system a reality, we must
connect three 8-bit latches to the outputs of the Codes array. Each will store one of the
bytes of the 3-byte instruction.
The command code will go to the first latch, the
high byte of the address to the second, and the low byte to the third. The output of the second and third
latches will become the 16-bit address of the cell in the array
Data. I have a question. Let's say the counter value is 0000, I have to write byte 10h. As I understand it, the command must be specified through the control panel on RAM (on the left). For example, I specified 10h, it turns out that 10h is written to all 3 latches (that is, 10h 10h 10h) ??? And how to write the command 10h 00 00 ?? Thanks in advance !

Answer 1

Let's say the counter value is 0000, I have to write byte 10h. As I understand it, the command must be specified through the control panel on RAM (on the left). For example, if you specified 10h, then it turns out that 10h is written to all 3 latches (that is, 10h 10h 10h) ???

No, it doesn't work. If the counter value is 0000, then you will write byte 10h only at address 0. And the machine will extract three bytes at addresses 0000, 0001 and 0002 into latches:

В нашем сумматоре каждая ко-
манда занимает по 3 байта и извлекается из памяти побайто-
во. Выборка одной команды занимает три цикла синхронизи-
рующего сигнала, а полный командный цикл — четыре цикла
синхронизирующего сигнала.

And how to write the command 10h 00 00 ??

You need to go to address 0001 and write byte 00, then to address 0002 and write byte 00.
The previous chapter describes how you can program such a memory.