I found that a single chip solution would be great to reduce development effort and improve performance of such a solution. The 6502 cpu is a fondlyremembered cpu for good reason. The mos technology 6502 is an 8bit microprocessor that was designed by a small team led. In my design the two 8255s behind con1 are used to simulate the host system. You precharge to vdd in phase 1 through a path with high drive strength and then in phase 2 only the fast pulldown network has to do any work if needed. Electronic design automation eda is a category of software tools for designing electronic systems such as printed circuit boards and integrated.
In particular, mensch was responsible for the design of the chips circuitry. Help support the museum by buying from the museum shop. They offered development software on a timeshare computer, the. Software for ic design and circuit design verification. Wdc is the home of the 65xx brand cmos microprocessors. But instead of rom and io chips, it uses a propeller microcontroller. Nowadays such detailed design is reserved for the patterns that are repeated over and over especially memory cells. The design team had formerly worked at motorola on the motorola 6800 project. For example, a system based on the 6502, where i could start with learning the basic of the chip and build up to creating a nes or c64. Please quote this reference id in any communication with the centre for computing history. Western design center wdc home of 65xx microprocessor technology as with the question from michaelkellett i am also curious why you are going with such an old chip brought back a lot of old memories.
The new direct register and stack relative addressing provides capability for reentrant, recursive and relocatable programming. The c746502 is a homemade implementation of the venerable mos 6502 microprocessor. Mensch was one of the primary designers of the 6502 and was part of the cadre of former motorola employees who defected to the pennsylvaniabased mos technology in late summer 1974, led by chuck peddle, whose idea for a lowcost cpu was rejected by motorola top brass. More interesting perhaps, the 6502 is the electronic brain of bender, the depraved robot in futurama, as revealed in a 1999 episode. The lstar project is a singleboard computer that you can build yourself, based on the venerable 6502 processor. The chip layout began in late 1972, the first 6800 chips were fabricated in. The propeller bitbangs the bus of the 6502 to make it think its in a computer thats not actually there. Bill mensch is cocreator of the 6502 chip, the microprocessor thats the heart of the atari 8bit computers, the apple, commodore 64, and many other classic computers. Eprom stores the monitor program and sram stores the variables and stack memory. His page includes schematics, monitor software, and an interesting 65c02. The finished program is then downloaded into the target 6502based computer. The retroshield 6502 is another example of a software implemented apple i. Dajgoros 6502 projects based in part on daryl rictors sbc2 design, dajgoros.
The mos technology 6502 typically sixtyfiveohtwo or sixfiveohtwo is an 8bit microprocessor that was designed by a small team led by chuck peddle for mos technology. I started to use spi in my designs with the sdcard interface and the netusb2 card for my csa computer. What is the best software for vlsi ic chip layout designing. You can use it to emulate early 6502based computers such as the apple1 or the osi challenger, or you can invent your own 6502 computer. Below is a brief description of each of our 65xx chips and a link to a quick reference. So all hardware and software design files are open source. Main parts are 6502 cpu, memory chips eprom and sram. At first, we want a real feeling for the capabilities of the 6502 prototype board, so at least lets have a keyboard, and a video screen to communicate with it. This talk will present the way from a chip package to a digital representation, how to simulate transistors in software, and new insights gained form. Today, almost all 6502 software is written on machines such as a pcs or unix boxes. The story of the 6502 makes up the first chapter of brian bagnalls on the edge. Its also not exactly an emulator, since it uses an actual 65c02. There are at least two famous robots that run on 6502. The 8 bit 6502 architecture and the first mos technology 6502 chip were designed in months.
The birth of the 6502 microprocessor in 1975 is, for many, a holy event. My goal is to make a daughtercard for every 8bit microprocessor out there. I wrote the monitor program using 6502 instructions. The most comprehensive ic design, verification, dfm and test technologies available today. The propeller monitors the address bus and data bus, and emulates memory and io. Dynamic nmos requires a large number of transmission gate transistors that are used to switch currents.
What is the most used ic design software in companies. You are invited to learn more about us, our products and our support for your 65xx brand embedded microprocessor pcb, asic andor fpga product development. The lstar is an opensource singleboard computer design that uses a propeller to control a 6502 processor. The monster 6502 uses the original dynamic nmos logic design. Contribute to jacgoudsmitpropeddle development by creating an account on github. We continually strive to remain the largest and most complete source for 6502related information in the world. The software that runs on the propeller determines how the 65c02 sees the world. His pages contain photos and descriptions of several 6502 sbc projects along with documentation and software for sos symon ii.
Our technologies address the most pressing challenges facing ic development teams for custom analog and digital, rtl synthesis, digital place and route, mixedsignal and. Permission is hereby granted, free of charge, to any person obtaining a copy of the software, schematics and pcb design and the associated documentation files the project, to deal in the project without restriction. While some program examples are oriented specifically to the rockwell aim singleboard computer, this in no way detracts from the perfect understanding of the programming algorithms and processes. I thought it might be fun to write some 6502 code for part of one of these robots, so i downloaded a sound sample of the terminator and loaded it on this chip along with some code to communicate with an mcp4921 dac chip. At the yearend of 2014, 32 years since i was a student, i picked the 6502 cpu and designed the microcomputer kit again with hex key and 7segment display. See also the source code repository for more 6502 software in assembly language.
The mos 6502 cpu, which was designed in 1975 and powered systems like the apple ii, the atari 2600, the nintendo nes and the commodore 64 for two decades, has always been subject to intense reverse engineering of its inner workings. In the old days i just watched a video about the 6502 design the full chip down to the layers, which is even more detailed than just the transistors were designed and drawn using tape by hand. This is a microprogrammed, discretecomponent 6502, a design architecture that was prevalent in 1970sera mainframe computers and predated modern. The memory and io spaces are selected by pld decoder. Is the software available to simulate building a computer from the. A disintegrated circuit project to make a complete, working transistorscale replica of the. Retroshield 6502 for arduino mega from 8bitforce on tindie. Its something in between, which i call a software defined computer. Here you will find public domain and shareware assemblers, disassemblers, compilers, and optimizers for crossdevelopment of 6502 programs, and also emulators and test suites. My favorite part of the description of the development of the 6502 is the actual chip layout. Along the top edge of the upper sheet there are several boxes marked with x or o which we believe allow for a 6501 or 6502 variant using only minor changes to the contact mask. The 6502 integrated circuit is a very popular microprocessor that is currently being used in generalpurpose microcomputers, video games, and personal computers. Building your own computer and knowing all the details of how it works, is arguably a lost art.
A simplified block diagram of the 6502 microprocessor kit is shown in figure 2. Processor design is the design engineering task of creating a processor, a key component of. This design enables the ttl6502 to update one or more registers in just one step. Computer programmers who program directly in assembly language want a cpu to support a full featured instruction set. The 6502 would also be quite acutely sensitive to the speed of memory, so the chip would not be able to run any faster than ram could feed it data it has only three user accessible 8bit registers, and only one of those can be used for computations. The chapter arrangement, starting with very fundamental material and gradually introducing more complex topics, is intended to increase your understanding of the 6502 integrated circuit in an orderly. Radicalbrad chose to design like its 1979, and limited his ode to the machines of his youth to the 6502 cpu and logic and ram chips available before 1980. The 6502 chip design used precharging for exactly that reason. The 6502 was inexpensive and easy to programtwo features that ultimately. The w65c816s extends the 65xx technology family to handle 16bit processing with a 16mb memory space while its emulation mode allows complete hardware and software compatibility with 64kb 6502 designs. This project lets you build a 6502 computer that helps you not just understand, but also control important details of how it works.
You can use it to emulate early 6502 based computers such as the apple1 or the osi challenger, or you can invent your own 6502 computer. The lstar project is an opensource singleboard computer design that uses a propeller microcontroller to control a 65c02 processor. Designed by western design center wdc, the processor is pin as well as software compatible to the original 6502 and runs at up. Microcomputer interfacing with the 8255 ppi chip ncr basic electronics course, with experiments ncr edp concepts course pet interfacing programming and interfacing the 6502, with experiments real time control with the trs80 16bi. Digging into technologys past archaeology magazine archive. The core of the flag register fr is made out of ten 74 dflipflops ic1519. The monster 6502 uses the original dynamic nmos logic design, implemented at the individual transistor level.
The chip handles four instead of eight devices the miso is separate for each device in case that separation is not necessary you can put the same signal on all pins there are four highactive interrupt inputs one for each device, with interrupt enable bits each, to forward the interrupts to the host 6502. My intention is to design the microcomputer board that uses 6502 as a cpu. Lstar connects a western design center w65c02 to a parallax propeller. A single bit in the status register could be set to change the cpu from one that looked exactly like the 6502 to a psuedo16 bit device with advanced instructions and even greater capability than the 6502. The internet didnt exist for downloads, and you didnt take your taperom chipdiskcartridge back to the store to upgrade game v1. This functioning monster 6502 is a larger than life. Chris cowens jimini platform cpc microsystems is a website created by christopher cowen detailing some of his microcomputer projects. We can use the 6502 cpu to operate the communications chip. The 6502 was revolutionary in its time, and widely adopted in early home computers and gaming consoles.
Western design center wdc home of 65xx microprocessor. This has many advantages over writing code directly on the 6502 machine in either a limited assembly language or machine code. A working, transistorscale replica of the mos 6502. A 6502 computer, with acres of breadboard and dozens of chips. The communications chip already knows how to communicate with the rs232 modem port on our pc. For various technical reasons, only a 4terminal mosfet can make an effective nmos transmission gate. Mouser sells classic 6502 antique processor toms hardware. The monster 6502 runs at about 120th the speed of the original, thanks to the much larger capacitance of the design. Modern 6502 software is almost always crossdeveloped on a pc or workstation platform. Assembly in one step by ron kneusel adapted from leo scanlons 6502 software design a classic introductory text online, also available here.