6502 test circuit. We see the letters appear on the screen.

6502 test circuit Join me, as I discuss supporting both MOS 6502 and WDC W65C02 CPU’s in a project Generic 6502 Emulation, Simulation and test suites There are many programs available here that allow you to test and debug 6502 code on your computer without a "real" 6502. Aug 3, 2023 · 6502 SBC prototype - testing PCB rev 1. Now we’ll give it a clock and a clean start every time you power on, rather than relying on a function generator. 777557100298 µs has elapsed and then reset to 0. And many others followed! My collection of 65XX ICs is Jul 27, 2004 · Programming the 65816 Including the 6502, 65C02, and 65802, by David Eyes and Ron Lichty, is a well-regarded tutorial and reference for the entire 6502 family. These leads are connected to the main PCB using 0. It is electrically compatible with the 6502 and offers lower power consumption due to the use of CMOS technology. Bender in Futurama has a 6502 processor for a brain. Accuracy / Compatibility Generally, the emulator simulates a NMOS 6502 MPU. Its core goals are accuracy, ease of development, clear documentation, and extensive test suites for validating correctness. A software engineer by trade, he decided to learn hardware from scratch and within months built his own custom computer based on the 6502. org Users Forum » Newbies All times are UTC Then add 6502. 1 The Power Supply Unit The power supply unit fitted to the BBC Microcomputer is a switch mode type. Oct 16, 2023 · The data sheet (. The On this page my experiences with an Apple 1 clone, my third! Build as kit, a nice experience and another 6502 system in the house. We're also building a cycle-accurate 6502 emulator Oct 19, 2024 · Task: Troubleshoot the 6502 Processor on Your Atari 8-Bit Computer Circuit Board Using an Oscilloscope Needed: Atari 8-bit computer, oscilloscope Time: 15-30 minutes Introduction Nothing is more frustrating than a beloved Atari 8-bit computer that isn’t booting properly into Memo Pad on the 400/800 or BASIC on the XLs and XEs. (Note that the other flag clearing instructions -- CLC, CLD, and CLI -- have corresponding flag setting instructions, namely SEC, SED, and SEI. 6502 test equipment pdf manual download. I've found some online, but they all use some kind of microcontroller, which I'd like to avoid. RC6502 Apple 1 SBC My third Apple 1 clone! A-One, Replica 1 are the other two. I don't think it's shorted, so does that mean it's a bad CPU? I do have a CPU from my apple II, but I don't want to put it into something that could kill it because it is a vintage chip. I used TASM assembler. Feb 15, 2020 · There are a number of different test circuits that can be built to test a 6502, but for simplicity, I used the simple NOP design, where a 1MHz clock is applied, and the data lines are 'hard wired' to either 5v or ground to pass a singlecommand to the CPU - in effect telling the CPU to run the same command over and over. This single board computer is a basic learning tool for programming the 6502 with low level instructions hex code. Note that I bought my new crystal clock from Mar 30, 2025 · Symon is a general purpose simulator for systems based on the MOS Technologies 6502 microprocessor and compatibles. Finally, the first v1. Stian Søreng wrote the original 6502 simulator in JavaScript. Hello everyone! I've decided to share my simple 6502 Emulator, meant to be readable and understandable by people that want to dive into CPU emulation. Several custom ICs in the Atari 8-bit computers have NMI pins for these signals including the 6502 CPU. The 6502 was revolutionary in its time, and widely adopted in early home computers and gaming consoles. Layouts of the IPC-9253 and IPC-9254 test board structures (CAF Test Boards) are shown in Figure 1. The emulator also dumps its memory before exiting for further debugging. org has lots of useful things, including a documents archive, a source code repository, and a forum. e. pdf) has the circuit, ideas for implementation, sample code, and more, which you can use to build such a circuit onto your own board, or you can buy mine. Apr 6, 2023 · On the E&L breadboard, I wired up a 6502 CPU circuit, to test several questionable 65C02 microprocessors. That means RAM, ROM, and basic I/O. Please send your contributions to us via in any format. Check out the video after the break to see some single stepping action. Thus it made sense to make a single test system to handle as many of these CPU/MCU’s as possible. Is there a simple test circuit (short of a whole system) that could be rigged up for each of these processors to verify that they are functional? The 6502 CPU, from MOS Technology, has been widely used since its debut in 1975. Designed by a group of people at MOS Technology led by Chuck Peddle, later of Commodore fame, and used in machines like the PET and C64. 1 Summary This method is for measurement of relative permittivity (er) and dissipation factor or loss tangent (tan d) of circuit board substrates under stripline conditions. I start with describing building the kit and getting it to work, last running some Apple 1 programs. We’re always looking for classic computer hardware in danger of being lost, especially broken or non-functional components created before about 1986. Material in this Test Methods Manual was voluntarily established by Technical Committees of IPC. Contribute to Kielan/6502-circuit-diagram development by creating an account on GitHub. They're used pulls from various places so I don't know the history on them. Much of the complexity of this development board lies in ensuring it can be expanded into a prototype of my final CPU card design. This is how it looks. A device that can test a 6502 MPU for partial functionality and prove if the device is faulty or fake Designed by Circuit Surgery in United Kingdom Dec 3, 1973 · 6625-00-327-6502 6625003276502 003276502 is a test set specifically designed for use in making examination of plug-in items, commonly referred to as modules or potted components, that are part of an electronic equipment. Having already built several of the 8-bit Museum's Motorola CPU NOP testers, it was now time to build a 6502 NOP tester. 6551 ACIA test program Page 1 of 1 Page 1 of 1 Board index » 6502. The way this works is the same as my Z80 CPU tester, which is wired such that, on power-up, the CPU goes to fetch the starting address, but the data bus is wired for the NOP instruction, which effectively does Oct 17, 2020 · The 6502 will set this flag automatically in response to an interrupt and restore it to its prior status on completion of the interrupt service routine. We see the letters appear on the screen. I needed a way to automatically reset the 6502 on power up. Department of Computer Science | The New Age of Discovery To design a circuit to meet this criteria, it must know when 31. Switch bouncing is the non-ideal behavior of any switch which generates multiple transitions of a single input. On this page manuals, most English, some German and other MOS Technology documents User manual Hardware manual Programming manual KIM Hints KIM Application Note #2 Interval timer Operation Circuit diagram poster KIM-2 – KIM-5 manuals, TIM MOS Technology Cross assembler KIMath Subroutines package First Book of KIM (with sources and binaries) MCS6500 Instruction Set Summary cards MOS MOS 6502 Emulator & Interactive Monitor. BBR and BBS can test any of the 8 bits without affecting any flags or using any registers. Pocket-sized 6502 coding! It doubles up as a 6502 programmable calculator, plays chess, and is a pretty good machine language learning tool. Featuring four easy to select output ranges and uses standard C cell alkaline batteries Test insulation resistance up to 10TΩ Four Insulation Test Voltage Output Ranges: 500V Brian Silverman‡ Playful Invention Co. Selectable clock frequency 1MHz, 2MHz, 4MHz and 8MHz with DIP switch. Also quickly adapted by computer designers like Steve Wozniak in the Apple series, the 1 and ] [ and 2 and 2e and 2c and 3. Over the years it has been manufactured by Western Design Center, NCR, GTE, Rockwell, Synertek and Sanyo. This was the first truly low-cost microprocessor that started the personal-computing revolution. Nick Morgan adapted the simulator for Easy 6502. Currently the PCB version is stable with the CPU overclocked to 32. Versions of 6502 found their way into the Atari 2600, Apple II, Nintendo Entertainment System, Commodore 64, Atari Lynx, BBC Micro and many other computers and game consoles On the E&L breadboard, I wired up a 6502 CPU circuit, to test several questionable 65C02 microprocessors. The new features are a reset circuit and a 4-digit hexadecimal display to monitor the address lines. It also includes the additional components needed for connecting it to the 6502 computer kit Here you will find a collection of useful programs and routines (mostly written in assembly language) that can be adapted to any 6502-based computer. I want to know what exactly each control signal in 6502, how the clock cycles work and additionally I would like to see an example of these control signals producing a single instruction from start to finish. This unit produces +5 volts at 3. This Introduction In this tiny ebook I’m going to show you how to get started writing 6502 assembly language. org forum finalised a verilog model of 6502 which was informed by the transistor netlist found in visual6502, but written by hand as a high level document of the function. Use the online emulator and assembler from the easy6502 tutorial and disassembler from mass:werk For in-depth 6502 investigation and some more advanced features, try our Advanced page. However, here are a few general rules for what to do with the ones whose functions don't interest you. Nov 19, 2023 · I had just received some old MOS 6502 microprocessor chips from AliExpress, for a project that I was working on. This CPU tester will make the 6502/6502C run the NOP instruction (opcode EA) and cycle through all the addresses. So, why Jan 1, 2025 · Task: Label the 6502 CPU, ANTIC, GTIA, POKEY, and PIA Chips for Easier Troubleshooting Using a Multimeter or Oscilloscope Needed: Printed Pinouts and Double-Sided Tape Time: 10-15 mins Disclosure: Note that as an eBay Partner Network Affiliate, I may earn from qualifying purchases. The C74-6502 is plug-in - 6502 Chiplab Back to 6502 homepage This page lets you run programs to run against a real 6502 chip. 175MHz, consistently passing the Dormann test suite and various memory soak tests. 0 How do you test and fix your first PCB rev? What did I learn from the experience of moving perfboard prototype to a PCB? Dec 22, 2020 · A simple test rig to test the basic operation of a 6502 processor using the NOP instruction provide a binary count on the Address Bus outputs. Interactive online analog & digital circuit simulator with built-in step by step CPU design examples (6502 compatible CPU) Introduction This site contains documentation for the various MOS 6502 opcodes and concepts, an editor that lets you write your own programs and a simulator that lets you run these. Supp… Note that as with TRB, the term reset in BBR is used to mean clear. Some instructions support several different modes while others may only support one. In this post we will cover a simple 555 Timer Clock circuit and reset circuit. The MOnSter 6502 A dis-integrated circuit project to make a complete, working transistor-scale replica of the classic MOS 6502 microprocessor. We can ignore the Address bus at the 8032 SP9000 Model 9000 - Swapping In A 6502 CPU To Test The Circuit Board Danger Cord - Episode 1436 Dave Bradley - 8-Bit Commodore Man 2. Oct 24, 2025 · 6502 Retro Console Part 2 Add a Reset and Clock Circuit In Part 1 we powered up the 6502 and watched it running a NOP test with just the CPU and LEDs on the address bus. 3. 0 gerbers sent off for prototype PCB manufacture in Nov 2023. What would be good would be to place the 6502 into a known state and run a program. these plug-in items are inclosed and sealed in a case, and are provided with plug-type connectors for insertion into or removal from the component or equipment of which they Aug 13, 2021 · It is a stand-alone board that can test basic functionality (executing instructions) of a 6502 CPU by generating NOP instructions. Sep 22, 2022 · I need a simple circuit to generate VGA or composite video for a project I'm working on. The three red leads carry +5 volts to various points Jan 8, 2012 · These components form circuits in a few simple ways according to how they contact each other, so by intersecting our polygons, we were able to create a complete digital model and transistor-level simulation of the chip. The simulation code and JavaScript demo by Barry and Brian Silverman was many months of work and is used for both chips. So, for this test circuit, I use PHI2, RW, /CS (Provided, in this case, by the C64 PLA) and the data bus as inputs. Each program is allowed to execute for 100 cycles. This tester allows you to perform a quick test of a 6502 CPU to determine if the chip is likely to be good or is faulty or fake. The method permits a wide variety of specimen configurations, varying in 2 days ago · A Non-Maskable Interrupt (NMI) signal is one in which the computer cannot ignore or mask. Apr 4, 2004 · A common use of BIT is to follow it with a BVC or BVS instruction to test bit 6 of a particular memory location. h and 6502. My intention is to design the microcomputer board that uses 6502 as a CPU. Oct 13, 2021 · 6502 PRIMER: Building your own 6502 computer What Do I Do With the "Mystery" Pins, SYNC, RDY, S. Mar 3, 2012 · The 65C02 microprocessor is an upgraded CMOS version of the MOS Technology 6502 8-bit CPU. New addressing mode for W65C02S. The main goal of this project is to understand how CPUs works by directly emulating one and to debug it by single stepping instructions. g. However, when the CPU is inserted, my Arduino shuts off. Source code is available on github visual6502. Even the Terminator was programmed in 6502. Also for: W65c02. The 8 LEDs are Oct 20, 2025 · Build the simplest working 6502 CPU circuit using only power, clock, and LEDs. This model is very accurate and can run classic 6502 programs, including Atari games. See the previous video for details about the Feb 21, 2025 · Clock Circuit for the Atari 800XL The NTSC Clock Circuit on an Atari 800XL Showing a Replaced Bad Resistor (R113, Blue), a Replaced Bad Capacitor (C109, Yellow), and a new Crystal Clock (Silver). Feb 23, 2019 · This is the second iteration of my 6502 tester. This is a great example to learn a bit more about how ALUs work and how "When one particular geek stuck one particular chip into one particular computer circuit board and booted it up, the universe skipped a beat. Whether you want to build your own C74-6502, or just learn more about its inner workings, this is the place to dig deeper. The kit is suitable for today student to learn many addressing modes and hardware of the 6502 CPU. Using the tools presented here, you can accurately test your 6502 code and perfect it before ever loading it into an actual machine. 6502. NOP Tester. Feb 10, 2022 · There are a number of test suites for 6502, each with their own intentions and peculiarities. memory access, arithmetic, etc. Development Tools, Emulators and test suites Jan 15, 2013 · Finally, he walks us through the circuit on the actual 6502 die, showing how the circuit is constructed in silicon. Mar 12, 2022 · 6502 System Design My goal for this stretch is to get the critical core features done. Symon simulates a complete Nov 4, 2021 · Test circuit and software After testing everything on breadboard, I connected the new interrupt controller to my 6502 computer. To achieve this, the pins are pushed as far as possible into the plastic holders before being soldered to the underside of the board. KH-Labs. Because of the processor's state machines mentioned earlier, you must purposely make it start out in a known state to begin orderly operation. Figure 1: A section of the 6502 showing, from left to right, (1) a chip die photograph from which a polygon representation was derived, (2) all polygons corresponding to physical chip layers (3) polygons reduced to substrate regions split by transistors, where green and red indicate substrate connected to ground and supply, and yellow indicates 6502 NOP generator circuit. I like the idea of using a 556 in my computer as it was available at the time of the 6502! Figure 2 shows the circuit so far. The 6502 processor was massive in the seventies and eighties, powering famous computers like the BBC Micro, Atari 2600, Commodore 64, Apple II, and the Nintendo Entertainment System. It’s about time to target some real hardware, so for the past few weeks I’ve been following Ben Eater’s 6502 computer tutorial. Both the Motorola MC6800 and MOS MCS6502 (which had a very similar design) have spawned many dozens of additional processors/microcontrollers that differ in pin out, features, process (CMOS/NMOS) speed, on board memory and other things, yet retain the same basic 6800 or 6502 architecture. Schematic coordinates in the… Apr 21, 2021 · This isn’t much of an inconvenience for a breadboard hobby computer, but it would be a bit clunky in my planned handheld 6502. Part one shows the construction of a NOP (No-Operation) Tester/Generator for the 6502 Processor, based on the Arduino schematic and code b Forum posts indicate that many members are uncomfortable with interrupts or even misunderstand why they are used. This section provides detailed explanations of the circuitry in each PCB o… The 6502 from November 11, 2009 to December 12, 2009, and the TIA from May 26, 2010 to July 7, 2010. If you have anything to contribute, whether in 6502 W65C02 6502C CPU tester NMOS / CMOS 1-8MHz from LP74S00 on Tindie6502 tester features advanced CPU testing compared to simple NOP testers executing NOP instruction in an endless loop cycle. The chip and its variants went on to become the main brains of ridiculously seminal computers like the Apple II 6502. The BRK instruction for both the NMOS 6502 and 65C02 is a 2 byte instruction. The most interesting feature is that it supports some new instructions. Jan 8, 2012 · These components form circuits in a few simple ways according to how they contact each other, so by intersecting our polygons, we were able to create a complete digital model and transistor-level simulation of the chip. Before moving on to write the code for the computer that will reside in the EEPROM, I want to test the circuit and make sure that it is outputting the scan codes and only the 8-bit portion that I’m interested in. This lack of orthogonality in the instruction set is one of the features that makes the 6502 trickier to program well. Holland, first edition, pages 37 & 53. a65 is an assembler sourcecode to test all valid opcodes and addressing modes of the original NMOS 6502 cpu. Read-Modify-Write, add 2 cycles. txt. Test board designs shall have sufficient minimum spacings on outer layers to ensure that surface insu-lation resistance failures do not occur. The Decimal flag controls how the 6502 adds and subtracts. IPC-TM-650 TEST METHODS MANUAL Scope This test procedure is designed to measure the level of extractable ionic contamination on the surface of printed boards and printed board assemblies by ion chroma-tography. org Users Forum » Newbies All times are UTC Jun 4, 2019 · 4 I'm trying to make a 6502 replica in Logisim. We continually strive to remain the largest and most complete source for 6502-related information in the world. Contribute to tdinucci/6502-emulator development by creating an account on GitHub. The idea came from the book "Advanced 6502 Interfacing" by John M. svg). I've changed the time base for every four address lines, to get somewhat accurate frequency measurements. O. I will use the one that uses the 556 for testing purposes, as I will be able to control the frequency and duty cycle. On the E&L breadboard, I wired up a 6502 CPU circuit, to test several questionable 65C02 microprocessors. Board index » 6502. There are plenty of resources on the web that discuss various reset circuits. It does this by presenting a permanent "NOP" (No Operation) instruction on the data pins, so that when a good device under test is powered up or reset, it will step through all the 64k addresses in sequence and the progress is Jul 8, 2021 · I’ve been using 6502 assembly for some hobby projects recently, but only testing in an emulator. Nov 30, 2011 · A toggle switch allows her to choose the crystal, or a 555 timer circuit which uses a push button to fire each clock pulse. (Instead of using a dedicated test suite, it can also be useful to run a monitor or BASIC interpreter, although the test coverage isn't very high and the run time is. The Load menu will load example programs contributed by various authors. I don't want to spend an inordinate amount of time only to find the processor is toast. Favourites are: Apple 1 monitor, Apple 6502 W65C02 NOP Tester from Circuit Surgery on TindieThis tester performs a quick test of a 6502 CPU to determine if the chip is likely to be good or is faulty/fake. Aug 7, 2016 · I wrote the monitor program using 6502 instructions. Longer pins could have been used for this, but the standard pins mean that the board rests firmly on top of the MEGA. This is what bringing the RST (say, "reset-not") pin low and then back high does. I built this testing circuit to see if it was good. Please note that this archive is for emulation of 65xx chips and is not intended for machine-specific emulators (Commodore 64, Apple II, etc). ). Another use of BIT is to set V, since the 6502 has a CLV instruction, but no corresponding SEV instruction. Jun 18, 2022 · To reduce this to a working circuit design, the 6502 team had to come up with a digital design of instruction decoders, arithmetic/logic unit (ALU), registers and data paths (high-level register-centric design) that could be implemented using individual gates made out of the NMOS transistors and depletion loads (low-level circuit design). Contribute to arcos-dev/sim65 development by creating an account on GitHub. org Mar 29, 2025 · The MOS Technology 6502 (P/N 156-1425-00) is an 8-bit microprocessor monolithic integrated circuit introduced in 1975 that was originally developed by a team led by Chuck Peddle at MOS Technology (later purchased by Commodore). The history of the 650… Feb 5, 2010 · Information about new additions and changes to the 6502. 11" blade type push-on receptacles. The 6502 processor (aka Sally) is a great place to start your Actually 22 articles: Intro & why a 6502, address decoding, memory-map requirements (plus why 6502 goes low-btye-first), interrupt connections, 74xx logic families and timing margins (plus "Do I need bus transceivers?", and static-handling precautions), clock generation, reset circuits, what to do with the "mystery" pins, construction for good Jul 18, 2024 · The key design of the original circuit is a set of flip-flops which latch the information on the data bus, and a switch that can be pressed to let the processor grab its next instruction, as well Books for the 6502 Fanatic If you're running to your local library for books, check out this list of must-read titles for the 6502 fanatic. A CPU passing this test will produce a flashing pattern on the three LEDs onboard, connected to address bits A13-A15. Why settle for a 6502 emulator when you could use the real thing! New here? Learn more about this system, and find some test programs here. The following sections list the complete set of 56 instructions in functional groups. Costs: about $12 in commonly av…. The utility model discloses a 6502 electric interlocking inserts circuit combined test ware in other direction, including the relay circuit unit, the input output port and the control cabinet. Sixth, replace any faulty components. c to your project and configure its build system so that CPU_6502_STATIC and CPU_6502_USE_LOCAL_HEADER are predefined when compiling the sources. doesn’t care about the second byte) by incrementing the program counter twice. The 6502 electric concentrated interlock system's that the relay circuit unit includes the 6502 electric concentrated interlock system switch area section circuit assembly that comprise the relay Hi everyone, I've recently gotten really interested in low level programming through watching Ben Eater's videos on making a 6502 computer from scratch (check them out if you haven't seen them, incredibly interesting series). 1 amps which are supplied to the main printed circuit board (main PCB) via seven flying leads. Nov 1, 2012 · This test procedure is designed to measure the level of anionic (including weak organic acid anions) and cationic contamination on the surface of circuit boards and circuit board assemblies by ion The C74-6502 microcode is composed of 195 individual microinstructions, each designed to configure the CPU’s datapath in particular ways to achieve specific operations. Commercial Support for the 6502 Distributors of 65xx chips, commercial development tools, trade magazines, and other commercial links useful to the 6502 enthusiast. 3. I don't want to overestimate my skill level The emulator only shows you what's going on under the hood of a 6502 CPU by executing a simple program (you could load yours) that the user must single-step. This primer was written to help with basic interrupt understanding and how to implement interrupts on 6502 systems, without getting into too much detail of individual hardware setups. It currently supports the full instruction set of the 6502 (plus a few extensions) and has an extremely rudimentary simulated I/O bus. There are a lot of ways of achieving this but in any scenario, I need to create some form of counting circuit. Garth Wilson’s 6502 Primer has a page covering several reset circuits. Programs are queued in the order they are received. Were it not for that, this system could be done with 6 or so ICs and maybe one For measurement of individual ionic species (type and level of residue) see IPC-TM-650, Test Method 2. Watch the address lines count with a NOP test. In addition the two index registers can not always be used interchangeably. The test was successful and demonstrates that the circuit and the 6502 is working. The 65C02_extended_opcodes_test. May 19, 2025 · 6502 PRIMER: Building your own 6502 computer Clock Generation All links verified 12/13/20. 0 PCB was assembled and tested. A lot of things could be done better, especially the graphics, but I focused more on the technical side of Jul 29, 2015 · The 6502 is a classic piece of computing history. The progress is displayed by the LED's. Fifth, use a multimeter to test the two transistors in the circuit. Here's a simple circuit, built from bits in the junk box, that has saved many hours of head scratching when that just finished new 6502 circuit failed to work first time. Build a 6502 computer Learn how computers work by building and programming a computer with the classic 6502 microprocessor. By eliminating the delays of CPU NOP testers While building the Retro Chip Tester, designed by Stephan Slabihoud, and documented on his 8bit-museum website, I noticed Stephan also designed CPU NOP testers and made designs as gerbers and BOM available. (The frequency of a parallel-resonant one will be slightly off in this This is a little circuit to test a 6502-family CPU. Jan 10, 2024 · Test out the program by writing it to the ROM, powering on the circuit and holding reset. It's a nice introduction, you Dec 27, 2017 · The C74-6502 is a homemade implementation of the venerable MOS 6502 microprocessor. PCB On the PCB the 6502 CPU is placed next to the clock and reset circuitry. As you can see, every address line divides the frequency by 2 because the program counter is incremented by 1 after each NOP operation. Dec 28, 2003 · Addressing Modes The 6502 processor provides several ways in which memory locations can be addressed. Nov 19, 2023 · I just received some old MOS 6502 microprocessor chips from AliExpress, for a project that I’m currently working on. This design is a microprogrammed, discrete-component 6502, an architecture that was prevalent in 1970s-era mainframe computers which pre-dated modern microprocessor technology. Students will learn basic of the computer hardware and software of the Feb 10, 2022 · In January 2010 user Xor on the 6502. Measure-ments are made by measuring resonances of a length of strip-line over a wide frequency range from below 1 GHz to about 14 GHz(1,2). Looking at these various mic… The !CS_IO signal can be generated with an 8-input NAND gate 74LS30 . 75 amps and -5 volts at 0. More complex systems can be built on top as things progress. It passes Klaus Dormann’s functional test suite for the 6502 and the extensive decimal mode (BCD) test for ADC and SBC instructions by Bruce Clark. Mar 25, 2025 · 6502 PRIMER: Building your own 6502 computer Reset Circuits All links verified or updated 12/13/20. Back then it was used in video consoles and home computers including the Atari, Apple II, Nintendo Entertainment System, BBC Micr… Mar 25, 2020 · Engineers like to build, but Nick Bild takes it to the stratosphere. With the PCB of the Retro Chip tester I laso bought the PCB’s for 6502 and Z80 NOP tester from him. This kit includes the components for re-creating the circuit from my "World's worst video card" videos. Symon is implemented in Java. \\nI am a complete beginner when it comes to electronics, so I spent a bit of time making useless circuits to toggle LED’s, then jumped right in to building the View and Download Circuit Surgery 6502 user manual online. If you want your interrupt service routine to permit other maskable interrupts, you must clear the I flag in your code. Introduction I have previously posted about using a multimeter and oscilloscope for testing and troubleshooting An Understandable 6502 Emulator. Now, I needed a way to test that the received chips were actually functional. This is a set of functional tests for the 6502/65C02 type processors. When the CPU is not inserted, the power rail is fine. KIM Uno - a 6502 KIM-1 Computer on Arduino: The KIM Uno is an open source replica of the classic 1976 KIM-1 computer. 640 in binary is 1010000000, which is a 10-bit number. It does this by presenting a permanent "NOP" (No Operation) instruction on the data pins of the device under test so that it will step through all the 64k addresses in sequence if it is not faulty or fake. 75K subscribers Subscribed Ben Eater's Reset Circuit Page 1 of 4 Go to page 1, 2, 3, 4 Next Page 1 of 4 Go to page 1, 2, 3, 4 Next Board index » 6502. Join me, as I discuss supporting both MOS 6502 and WDC W65C02 CPU’s in a project, then building a Join me, as I discuss supporting both MOS 6502 and WDC W65C02 CPU's in a project, then building a CPU NOP tester, and finally using it to test my old MOS 6502 chips and a new W65C02 CPU chip. We've found some interesting things on the 6502, from the layout level, up through circuit level to the programmer visible level. Mitchell MIT6502 5KV Insulation Resistance Tester and Megohmmeter The MIT6502 5kV insulation resistance testing Megohmmeter is built into a rugged hard case and can handle the rugged outdoor environments with ease. The data l The test was successful and demonstrates that the circuit and the 6502 is working. This is quick test of a standard 6502 processor with my newly built clock and a NOP code which forces the CPU to count up the program counter. org website. The latter follows the circuit of the original MOS Technology 6502 (as reverse engineered at visual6502. This observation led me to test the resistors in that circuit which were all fine (see NMI circuit diagram below). The circuit is simple and easy build. Adding a capacitor across the switch can help to clean things up but it’s not a good long-term solution. Same principle: the computer part is identicl tot the Apple 1 (with modern RAM and Although this circuit will reset the 6502, it could cause problems, due to the nature of switch bounce. Figure 1: 6502 Microprocessor kit To get the most basic test case, let's suppose I only have a 74377 8bit register (With a /E input, and positive edge triggered clock) to hold 1-byte value, and a 74244 tri-state buffer to output that same value to the data bus when requested. Krzysztof's Projects - Krzysztof Swiecicki is a 6502 enthusiast from Poland. Emulation is a facinating and incredible capability. MC6500 Microcomputer Family Programming Manual describes the original 6502 instruction set in detail. org Users Forum » Newbies All times are UTC A 6502 processor simulator with cloud program saving. This includes everything from articles and project descriptions to schematics and source code. On the 6502 and 65C02, bit 7 is typically the most convenient bit to use for I/O and software flags because it can be tested by several instructions, such as BIT and LDA. ) In this case, the V flag is Mar 19, 2022 · A two-part video. Branch taken, add 1 cycle if branch is taken. 28, Ionic Analysis of Circuit Boards, Ion Chromatography Method. The board has hex keypad and 7-segment display for entering the instruction hex code and test it directly. , Φ1, MLB, BE, and VPB? First, rest assured that for simple systems, it is not necessary to understand and use every single pin. 6502 Minimal Computer (with Arduino MEGA) Part 1: The 6502 microprocessor first appeared in 1975 and was designed by a small team led by Chuck Peddle for MOS Technology. www. The test is to force a NOP instruction on the data lines. If you're using an old NMOS 6502, you will have to have a square wave input to the Φ0 pin. As I don't have the money to build something similar myself, I decided to try my hand at writing a 6502 emulator using python. The 6502_functional_test. The geek was Steve Wozniak, the computer was the Apple I, and the chip was the 6502, an 8-bit microprocessor developed by MOS Technology. Feb 22, 2025 · This is a nice example of repairing an Atari computer by looking for clues using an oscilloscope and following the related circuits on a circuit diagram. Jul 27, 2025 · 6502 and W65C02 CPU "NOP" Tester The 6502 CPU is used in a number of vintage computers and games consoles including the Acorn BBC Micro, Apple I & II, Commodore 64, PET, Atari, Nintendo, and many more. To remove the bouncing from the circuit Switch Debouncing Circuit is used. However, it doesn’t demonstrate anything further! The addresses that are being displayed are meaningless. Versions of this CPU were found in everything from the Apple ][, to the Nintendo Entertainment System, and the Commodore 64. A crystal oscillator is fed into a 4-bit binary counter acting as a clock divider for the CPU. The goal of this project is to make a general-purpose 6502 computer run as quickly as I can, using standard through-hole parts. x6502: a simple 6502 CPU emulator x6502 is an emulator for the 6502 class of processors. All of the required signals are exposed via pin headers on my 6502 computer, more information about that can be found on previous blog posts. The NMOS and CMOS devices simply skips the second byte (i. It has pluggable support for additional I/O modules, and I've OVERVIEW The 6502 Microprocessor kit is a new design single board computer using the G65SC02 as a CPU. A commonly used clock-generation circuit went like this: With this circuit, use a series-resonant crystal to get the frequency printed on it. Before recycling or tossing your old computers or game systems, please check our website to see if they could become a valuable contribution to computer history. svg schematic of the 6502 microprocessor. Emulators allow your computer to simulate the functions of a 6502 microprocessor (and in some cases the support chips) right on your computer, entirely through software. Implicit For Card B holds the ALU, the Control Unit (CU), the Status Register (P), as well as other special registers which are used to implement specific 6502 Undocumented Opcodes. 768MHz, and the breadboard prototype is stable at 25. Switch bounce is a problem caused by the contacts of switches making contact multiple times before settling down. a65c tests all additional opcodes of the 65C02 processor including undefined opcodes. I first built this modified circuit, changed the ACIA register definitions accordingly and verified that my hello world program still works. org is a resource for people interested in building hardware or writing software for the 6502 microprocessor and its relatives. This is an svg schematic of a 6502 microprocessor, consisting of a block diagram (bd. Having already built several Motorola CPU NOP testers, it was now time to build a 6502 NOP tester. org) very closely, and the layout of the chip quite closely: differences with the original are noted in the file diff. svg) and a circuit diagram (cd. Is there a book about 6502 or other processor that goes in depth about it's control signals? Summary I have two clock circuits: one using a 556 timer IC and the other using a crystal oscillator. westerndesigncenter The circuit board is quite compact and the underside plugs directly into the Arduino MEGA. !CE and !OE are connected to !CS_RAM and 1. A Normal Repeating Waveform for Pin #6 (NMI) of the 6502 CPU 6502 CPU and NMI Circuit U29 CO60472 Delay Line Circuit Instructions I built an 8-bit computer, and it's not working. Part 5: Video: What is a stack and how does it work? Notes and steps taken: 6625-00-327-6502 A test set specifically designed for use in making examination of plug-in items, commonly referred to as modules or potted components, that are part of an electronic equipment. Then i built the !CS_RAM circuit using a 74LS00 NAND and one 74LS04 inverter and connected a 61256 32k x 8 SRAM to the address and data buses. Here’s a simple circuit, built from bits in the junk box, that has saved many hours of head scratching when that just finished new 6502 circuit failed to work first time. Hope y'all appreciate it, feel free to give me feedback and to contribute! Nov 20, 2023 · You'll find the 6502 NOP Tester topic here: Building a 6502 (and W65C02) NOP Tester The Schematic and PCB layout was completed, and v1. I have lined up the 6502 and 6522 ICs so that they The 6502 has a relatively basic set of instructions, many having similar functions (e. In a suitable browser, the circuit diagram has wires which can be highlighted on mouseover or click. Video Klaus' 6502 Board - Klaus Mussler designed and built a small printed circuit board with 32K of RAM, 16K of ROM, three VIAs for I/O, and a 6551 ACIA and MAX232 circuit for RS-232 communications. orfrpma zwrzd djydzo zocibiwd zam fxmzh usnc ohuz tguo ljofca vfz ewlekz uqvr uwpwj ualxs