Emulator for the Bill's Drum 1 Architecture in development. Total toy, total crap.

(bdi is pronounced "Beady Eye")

32 long drum lines of 32 words each. 1024 Words. 10bit addresses.

Memory access is only load / store to from registers.

Up to 32 single word registers as "short lines." 5 bit addresses. Each register gets a name.

In Drum Computer fasion each operation includes a Next Instruction address.

Read one word from any address in memory and write to any register.

Read one word from any register and write to any memory address

Read one word from any register, writing to any other register

The only way anything interesting happens on the BDI is via special registers.

Reading and writing to the A register is unremarkable. Whatever value is written is stored.

Writing to the A+ register occurs via a serial adder who's other input is the A register.

Reading from the A+ register results in the same value as the A register.

C and D may be read and written normally.

Reading the C+D reads the values of these two via a serial adder.

They may be convenient for loops. Call them Count and Decrement, put N in C and -1 in D. Each time through the loop effect a transfer of C+D -> C to decrement the count. A subsequent transfer of C -> BRA can be used to branch out of the loop when C is reaches zero.

Writing any value to the OUT register results in the first 8 bits of the word being written to the serial terminal.

Reading the OUT register returns the value of the terminal's CTS Line

Is this realistic in hardware?

Writing any non-zero value to the Branch Register causes the next instruction to be taken from N+1 instead of N.

Writing any non-zero instruction to the Halt Register halts computation.

Perhaps an NCAR style approach?

Some bitwise operations?

Input?