Update: Compiler Added

Intro

Hey guys. I have finally finished a project that I have been working on for months

now, my very own PowderToy computer! The C4C 1 8-bit Computer is now fully functional,

complete with detailed documentation and a block diagram of the internals. I am very proud

to join the community of people who develop complex electronics and computers on TPT.

I am probably the youngest person to finish such a project, being a 14 year old freshman

in high school. You guys are truly amazing, and the feats you accomplish together as a

community are incredible (60 hz computer, GPU, video game inside a video game, etc.)

I hope now to play my part in this incredible community.

Detailed Specifications

Before we get into the computer, here is a complete specification for further reading:

https://pastebin.com/zLKL4Fth

And here is the block diagram:

http://tinyurl.com/C4C-1-Spec-PDF

Features

• An 8-bit Semi-Von Neumann architecture (data/addresses are 8 bits wide at maximum)
• A 256 byte ROM and 256 byte RAM
• 16 general purpose registers (AX - PX)
• Hexadecimal keyboard and display
• A 7 function ALU
• 16 assembly instructions
• A microcoded CPU
• OLD TECHNOLOGY!!! We've got ARAY/FILT/INST, and even a subframe ray gun! See if you can find it.
• A 0.02 HZ cycle speed to teach patience

Programming Instructions

Finally, we get to the programming refrence. You need technical knowledge for this section. It is taken from the reference. In the ROM, data is stored in filt. Filt uses a hex number which corresponds to a 30-bit wavelength in the CTYPE:

Instruction Bitfield:

• [11111][xxxx][xxxxxxxx][xxxxxxxx][00000] where INST = which instruction
• [IDENT][INST][OPERANDA][OPERANDB][EMPTY]

Data Bitfield:

• [0000000000000000000000][xxxxxxxx]
• [               UNUSED             ][   DATA  ]

Register bitfield (for use in operands):

• [0000][xxxx] where addr = address of register from 0 - 15 (AX - PX)
• [NONE][ADDR]

And an assembly instruction corresponding to instructions or data:

• Instruction: [MNEMONIC] [OPERANDA], [OPERANDB]
• Data: DB [8BIT-BYTE]

Update: Use the compiler linked at top, type assembly instruction, followed by binary operands

into compiler, then press compile instruction. When done with entire program, press create image

and copy that ROM.

To program the C4C 1 CPU in PowderToy, there are several steps you need to take:

1. Write out the instruction in assembly mnemonics, e.g. MOV AX, BX
2. Find the binary address corresponding to the instruction, e.g. 0001 for MOV
3. Encode the operands in binary, e.g. OPERANDA[AX] becomes 00000000 and OPERANDB[BX] becomes 00000001
4. Put the instruction together in binary, with the identifier at the front, followed by the binary instruction address, followed by the operands, and lastly the sequence 00000 e.g. 11111 + 0001 + 00000000 + 00000001 + 00000 => 111110001000000000000000100000
5. Convert the instruction from binary to hex, e.g. 111110001000000000000000100000 => 0x3E200020
6. Set the PROP tool to edit CTYPE and paste the hex instruction with the "0x" at the front, click OK and click on the filt memory cell you want to write to. The cells go from left to right, then top to bottom. (Address 0 - 15 first row, 16 - 31 second row, and so on until address 255)

Putting data into the ROM is similar. Simply convert the 8 bit byte to hex, put the 0x in front of it,

paste it into the PROP tool with it set to CTYPE, and click on the filt memory cell you want to write to.

Instruction Reference

HLT [NONE]

• Address: 0000
• Stops and resets the CPU

MOV a, b [REGISTER],[REGISTER]

• Address: 0001
• Copies the value of register b to register a

STORE a, b [RAMADDR], [REGISTER]

• Address: 0010
• Stores contents of register b in RAM memory location a

LOADRAM a, b [REGISTER], [RAMADDR]

• Address: 0011
• Loads contents of RAM memory location b into register a

LOADROM a, b, [REGISTER], [ROMADDR]

• Address: 0100
• Loads contents of ROM memory location b into register a

DB a [CONSTANT]

• Address: None
• This is a special instruction - the value of a is simply stored in the ROM, using the data bitfield. DB stands for data byte - the instruction stores one 8 bit byte. This data can be retreived using LOADROM, where the value for the ROM address would be the address of this byte

JMP a [ROMADDR]

• Address: 0101
• Changes value of instruction pointer to the value of a - this is an unconditional jump

JZ a, b [ROMADDR], [REGISTER]

• Address: 0110
• Changes the value of the instruction pointer to the value of a only if the value of register b is zero - this is a conditional jump

JNZ a, b [ROMADDR], [REGISTER]

• Address: 0111
• Changes the value of the instruction pointer to the value of a only if the value of register b is not zero - this is a conditional jump

OR a, b [REGISTER], [REGISTER]

• Address: 1000
• Performs logical or on values of registers a and b, stores result in register a

AND a, b [REGISTER], [REGISTER]

• Address: 1001
• Performs logical and on values of registers a and b, stores result in register a

NOT a [REGISTER]

• Address: 1010
• Performs logical not on value stored in register a and stores the value in register a

SHL a [REGISTER]

• Address: 1011
• Performs an overflow, destructive left shift on register a

SHR a [REGISTER]

• Address: 1100
• Performs an overflow, destructive right shift on register a

ADD a, b [REGISTER], [REGISTER]

• Address: 1101
• Adds the values of registers a and b together, stores result in register a

RECV a [REGISTER]

• Address: 1110
• Receive a value into register a from the I/O port

SEND a [REGISTER]

• Address: 1111
• Send a value from register a to the I/O port

Example: Fibonnaci Sequence Program

DB 1                     ;Store the value 1 in memory cell 0

SEND AX               ;Since all registers are 0 at CPU start, I can output 0

LOADROM AX, 0     ;Load memory cell 0 (a value of 1) into AX

SEND AX                ;Perform fibbonaci

MOV CX, AX

ADD AX, BX

MOV CX, BX

SEND AX                 ;Output fibonnaci

JZ 11, AX                ;Jump to terminate if AX overflows

JMP 4                      ;Jump back to fibonnaci

DB 0xEE                  ;Store 0xEE

LOADROM AX, 10     ;Retrieve 0xEE

SEND AX                 ;Print "EE" on display, signifies overflow

DB 0                       ;Why the hell would I want to end my program in addr 13?

HLT                         ;Halt

Update: Virtual Machine Emulator for C4C 1

I made an emulator in C for the C4C 1 machine. The code is here:

https://pastebin.com/7X1KamHs

Conclusion

I am very happy to finally be done with this. If you have any bugs, post them in this thread or

DM them to me using the PowderToy message system. Also post or send me any questions.

Thanks, @Eliasdbr! Also @QuanTech, you could try making a general compiler... but that is kind of difficult. I am still thinking if I want to make one.

@Quantech Oh my god! I forgot was that was called! Well, that's kind of sad. I am really dumb for not knowing that. Anyways, in your compiler, I see you are missing DB. You could make a seperate input for only data, or you could use your operand A or B input.

@Quantech

Two questions: do you input DB through the Operand A or Operand B panel? Also, you have a bug in your design where if I spam either the Operand A or B panel with spark the pstn overshoots the filt line. You need to change the maximum extension distance of the pstn to one by setting the tmp2 value. This also applies to spamming every button except DB, because they also connect to pstn. 

@QuanTech DB works a little differently than how you put it. In the DB instruction, there is no instruction identifier (first 5 bits) and the data is stored in the last 8 bits.