4 Most minimal extension of friend's 'CPU In a Week' in a day

4 : Most minimal extension of friend's 'CPU In a Week' in a day

Design render
  • Author: Gregory Kollmer
  • Description: 8-bit Single-Cycle CPU
  • GitHub repository
  • Clock: 0 Hz

How it works

This project is the most minimal extension (add CLR & MUL to ISA) of Ramyad Hadidi's 8-bit CPU that details the design and implementation of an 8-bit single-cycle microprocessor. The processor includes a register file and an Arithmetic Logic Unit (ALU). The design was crafted to handle a simple instruction set architecture (ISA) that supports basic ALU operations, load/store operations, and status checks for the ALU carry -- all within less than a week. While the current version lacks a program counter and external memory, thus omitting any form of jump operations, it provides a solid foundation for understanding basic computational operations within a custom CPU architecture.

ISCA Overview

The ISA is straightforward and is primarily focused on register operations and basic arithmetic/logic functions. Below is the breakdown of the instruction set:

// ISA --------------------------------------------------------------
//-- R level
`define MVR 4'b0000            // Move Register
`define LDB 4'b0001            // Load Byte into Regsiter
`define STB 4'b0010            // Store Byte from Regsiter
`define RDS 4'b0011            // Read (store) processor status
// 1'b0100 NOP
// 1'b0101 NOP
// 1'b0110 NOP
// 1'b0111 NOP
//-- Arithmatics
`define NOT {1'b1, `ALU_NOT}
`define AND {1'b1, `ALU_AND}
`define ORA {1'b1, `ALU_ORA}
`define ADD {1'b1, `ALU_ADD}
`define SUB {1'b1, `ALU_SUB}
`define XOR {1'b1, `ALU_XOR}
`define INC {1'b1, `ALU_INC}
`define MUL {1'b1, `ALU_MUL}
// 1'b1111 NOP

How to test

The processor has been tested through a suite of 12 testbenches, each designed to validate a specific functionality or operation. These testbenches cover basic ALU operations, data movement between registers, and the load/store functionalities. Although basic operational tests are passing, timing interactions between instructions have not been exhaustively verified, and it is anticipated that a sophisticated compiler would handle these timing considerations effectively, reminiscent of approaches taken in historical computing systems. [ADD TESTS FOR MUL EXTENSION]

External hardware

Currently, the processor does not interface with any external hardware components. It operates entirely within a simulated environment where all inputs and outputs are managed through testbenches. This setup is ideal for educational purposes or for foundational experimentation in CPU design.

IO

#InputOutputBidirectional
0Register 1 (R1) Address bit 0Data out bit 0 (either register data / Processor stat)Data in bit 0 / Register 3 (R3) Address bit 0
1Register 1 (R1) Address bit 1Data out bit 1 (either register data / 0)Data in bit 1 / Register 3 (R3) Address bit 1
2Register 1 (R1) Address bit 2Data out bit 2 (either register data / 0)Data in bit 2 / Register 3 (R3) Address bit 2
3Register 1 (R1) Address bit 3Data out bit 3 (either register data / 0)Data in bit 3 / Register 3 (R3) Address bit 3
4Instruction ISA Opcode bit 0Data out bit 4 (either register data / 0)Data in bit 4 / Register 2 (R2) Address bit 0
5Instruction ISA Opcode bit 1Data out bit 5 (either register data / 0)Data in bit 5 / Register 2 (R2) Address bit 1
6Instruction ISA Opcode bit 2Data out bit 6 (either register data / 0)Data in bit 6 / Register 2 (R2) Address bit 2
7Instruction ISA Opcode bit 3Data out bit 7 (either register data / 0)Data in bit 7 / Register 2 (R2) Address bit 3

Chip location

Controller Mux Mux Mux Mux Mux Mux Mux Mux Mux Mux Mux Analog Mux Mux Mux Mux Mux Mux Mux Mux Mux Mux Mux Analog Mux Mux Mux Mux Mux Mux Mux Mux Mux Mux tt_um_chip_rom (Chip ROM) tt_um_factory_test (TinyTapeout 06 Factory Test) tt_um_analog_factory_test (TT06 Analog Factory Test) tt_um_analog_factory_test (TT06 Analog Factory Test) tt_um_urish_charge_pump (Dickson Charge Pump) tt_um_psychogenic_wowa (WoWA) tt_um_oscillating_bones (Oscillating Bones) tt_um_kevinwguan (Crossbar Array) tt_um_coloquinte_moosic (Moosic logic-locked design) tt_um_alexsegura_pong (Pong) tt_um_iron_violet_simon (Iron Violet) tt_um_tomkeddie_a (VGA Experiments in Tennis) tt_um_MichaelBell_tinyQV (TinyQV Risc-V SoC) tt_um_andychip1_sn74169 (sn74169) tt_um_mattvenn_r2r_dac (Analog 8bit R2R DAC) tt_um_thorkn_audiochip_v2 (AudioChip_V2) tt_um_faramire_gate_guesser (Gate Guesser) tt_um_urish_simon (Simon Says game) tt_um_TT06_SAR_wulffern (TT06 8-bit SAR ADC) tt_um_soundgen (soundgen) tt_um_ledcontroller_Gatsch (ledcontroller) tt_um_digitaler_filter_rathmayr (Digitaler Filter) tt_um_histefan_top (Snake Game) tt_um_mayrmichael_wave_generator (Wave Generator) tt_um_advanced_counter (jku-tt06-advanced-counter) tt_um_FanCTRL_DomnikBrandstetter (PI-Based Fan Controller) tt_um_ps2_morse_encoder_top (PS/2 Keyboard to Morse Code Encoder) tt_um_calculator_muehlbb (16-bit calculator) tt_um_hpretl_tt06_tempsens (Temperature Sensor NG) tt_um_haeuslermarkus_fir_filter (FIR Filter with adaptable coefficients) tt_um_mattvenn_rgb_mixer (RGB Mixer demo) tt_um_analog_loopback (Analog loopback) tt_um_entwurf_integrierter_schaltungen_hadner (Projekt KEIS Hadner Thomas) tt_um_seven_segment_fun1 (7-segment-FUN) tt_um_moving_average_master (Moving average filter) tt_um_rgbled_decoder (SPI to RGBLED Decoder/Driver) tt_um_4bit_cpu_with_fsm (4-Bit CPU mit FSM) tt_um_flappy_bird (Flappy Bird) tt_um_drops (drops) tt_um_enieman (UART-Programmable RISC-V 32I Core) tt_um_gabejessil_timer (2 Player Game) 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tt_um_wokwi_395055341723330561 (Workshop_chip) tt_um_jduchniewicz_prng (8-bit PRNG) tt_um_wokwi_395054564978002945 (Bestagon LED matrix driver) tt_um_wokwi_395054466384583681 (1-Bit ALU 2) tt_um_wokwi_395058308283408385 (test for tiny tapeout hackaday) tt_um_s1pu11i_simple_nco (Simple NCO) tt_um_wokwi_395055359324730369 (Tiny_Tapeout_6_Frank) tt_um_disp1 (Display test 1) tt_um_pckys_game (PCKY´s Successive Approximation Game) tt_um_tiny_shader_mole99 (Tiny Shader) tt_um_wokwi_393815624518031361 (My Chip) tt_um_minibyte (Minibyte CPU) tt_um_emilian_rf_playground (IDAC8 based on divide current by 2) tt_um_triple_watchdog (Triple Watchdog) tt_um_wokwi_395142547244224513 (EFAB Demo 2) tt_um_chisel_hello_schoeberl (Chisel Hello World) tt_um_aiju_8080 (8080 CPU) tt_um_wokwi_395134712676183041 (Inverters) tt_um_nubcore_default_tape (DEFAULT) tt_um_wuehr1999_servotester (Servotester) tt_um_wokwi_395055722430895105 (Servo Signal Tester) tt_um_exai_izhikevich_neuron (Izhikevich Neuron) 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modulation tester) tt_um_csit_luks (CSIT-Luks) tt_um_wokwi_395357890431011841 (Trivium Non-Linear Feedback Shift Register) tt_um_drburke3_top (SADdiff_v1) tt_um_cejmu_riscv (TinyRV1 CPU) tt_um_rejunity_current_cmp (Analog Current Comparator) tt_um_loco_choco (BF Processor) tt_um_qubitbytes_alive (It's Alive) tt_um_wokwi_395061443288867841 (BCD to single 7 segment display Converter) tt_um_SJ (SiliconJackets_Systolic_Array) tt_um_ejfogleman_smsdac (8-bit DEM R2R DAC) tt_um_wokwi_395055455727667201 (Hardware Trojan Part II) tt_um_ericsmi_weste_problem_4_11 (Measurement of CMOS VLSI Design Problem 4.11) tt_um_wokwi_395034561853515777 (2 bit Binary Calculator) tt_um_mw73_pmic (Power Management IC) tt_um_Counter_1_shivam (8-bit Binary Counter) tt_um_wokwi_395054508867644417 (SynchMux) tt_um_otp_encryptor (TT06 OTP Encryptor) tt_um_wokwi_395514572866576385 (Parity Generator) tt_um_ADPCM_COMPRESSOR (ADPCM Encoder Audio Compressor) tt_um_3515_sequenceDetector (Sequence detector using 7-segment) tt_um_faramire_stopwatch (Simple Stopwatch) tt_um_ks_pyamnihc (Karplus-Strong String Synthesis) tt_um_dlmiles_muldiv8 (MULDIV unit (8-bit signed/unsigned)) tt_um_dlmiles_muldiv8_sky130faha (MULDIV unit (8-bit signed/unsigned) with sky130 HA/FA cells) tt_um_tommythorn_ncl_lfsr (NCL LFSR) tt_um_lk_ans_top (ANS Encoder/Decoder) tt_um_MichaelBell_latch_mem (Latch RAM (64 bytes)) tt_um_wokwi_395179352683141121 (Combination Lock) tt_um_Uart_Transciver (UART Transceiver) tt_um_dgkaminski (4-Bit ALU) tt_um_DigitalClockTop (TDM Digital Clock) tt_um_wokwi_394640918790880257 (IFSC Keypad Locker) tt_um_wokwi_395355133883896833 (BIT COMPARATOR) tt_um_alu (SumLatchUART_System) tt_um_alfiero88_VCII (VCII) tt_um_ALU (3-bit ALU) tt_um_topTDC (Convertidor de Tiempo a Digital (TDC)) tt_um_UABCReloj (24 H Clock) tt_um_CDMA_Santiago (CDMA_2024) tt_um_dr_skyler_clock (Clock) tt_um_motor (motor a pasos) tt_um_mult_2b (mult_2b) tt_um_CodHex7seg (Decodificador binario a display 7 segmentos hexadecimal) tt_um_S2P (Serial to Parallel Register) tt_um_PWM (PWM) tt_um_ss_register (serie_serie_register) tt_um_stepper (Stepper) tt_um_g3f (Generador digital trifásico) tt_um_ALU_DECODERS (ALU with a Gray and Octal decoders) tt_um_ram (4 bit RAM) tt_um_sap_1 (SAP-1 Computer) tt_um_guitar_pedal (Integrated Distorion Pedal) tt_um_mbalestrini_usb_cdc_devices (Two ports USB CDC device) tt_um_adammaj (Tiny ALU) tt_um_wokwi_395567106413190145 (4-Bit Full Adder and Subtractor with Hardware Trojan) tt_um_gak25_8bit_cpu_ext (Most minimal extension of friend's 'CPU In a Week' in a day) tt_um_hsc_tdc (UCSC HW Systems Collective, TDC) tt_um_BoothMulti_hhrb98 (UACJ-MIE-Booth 4) tt_um_dlmiles_poc_fskmodem_hdlctrx (FSK Modem +HDLC +UART (PoC)) tt_um_simplez_rcoeurjoly (tt6-simplez) tt_um_nurirfansyah_alits01 (Analog Test Circuit ITS: VCO) tt_um_ppca (drEEm tEEm PPCA) tt_um_wokwi_395522292785089537 (Displays CIt) tt_um_fpu (Dgrid_FPU) tt_um_duk_lif (Leaky Integrate and fire neuron(LIF)) tt_um_bomba1 (Latin_bomba) tt_um_chatgpt_rsnn_paolaunisa (ChatGPT designed Recurrent Spiking Neural Network) tt_um_bit_ctrl (Bit Control) tt_um_array_multiplier_hhrb98 (Array Multiplier) tt_um_wallace_hhrb98 (UACJ-Wallace multiplier) tt_um_I2C_to_SPI (TinyTapeout SPI Master) tt_um_rng (Random number generator) tt_um_wokwi_395599496098067457 (EVEN AND ODD COUNTERS) tt_um_8bitALU (8bit ALU) tt_um_aleena (Analog Sigmoid) tt_um_rejunity_1_58bit (Ternary 1.58-bit x 8-bit matrix multiplier) tt_um_rejunity_fp4_mul_i8 (FP4 x 8-bit matrix multiplier) tt_um_PWM_Controller (PWM Controller) tt_um_couchand_cora16 (CORA-16) tt_um_frq_divider (clk frequency divider controled by rom) tt_um_wokwi_390913889347409921 (Notre Dame Dorms LED) tt_um_timer_counter_UGM (4-Digit Scanning Digital Timer Counter) tt_um_koconnor_kstep (kstep) tt_um_lancemitrex (DIP Switch to HEX 7-segment Display) tt_um_PWM_Sine_UART (PWM_Sinewave_UART) tt_um_nicklausthompson_twi_monitor (TWI Monitor) tt_um_wokwi_395615790979120129 (Cambio de giro de motor CD) tt_um_ancho (Circuito PWM con ciclo de trabajo configurable) tt_um_wokwi_395618714068432897 (32b Fibonacci Original) tt_um_voting_thingey (Voting thingey) tt_um_hsc_tdc_buf (UCSC HW Systems Collective, TDC - BUF2x1) tt_um_hsc_tdc_mux (UCSC HW Systems Collective, TDC - MUX2x1) tt_um_petersn_micro1 (14 Hour Simple Computer) tt_um_sanojn_tlv2556_interface (UART interface to ADC TLV2556 (VHDL Test)) tt_um_gray_sobel (Gray scale and Sobel filter) tt_um_wokwi_395614106833794049 (Universal gates) Available Available Available Available Available Available Available Available Available Available Available Available Available Available Available Available Available Available Available Available Available Available Available Available Available Available Available Available Available Available Available Available Available Available Available Available Available Available Available Available Available Available Available Available Available Available Available Available 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