With the Wonderful Chip Scarcity nevertheless delaying deliveries of new elements, now could possibly be a fantastic time to appear close to your lab and examine these piles of chips that you thought “might arrive in helpful a person day”. Possibilities are you will locate a very good stack of 74xx series logic, once ubiquitous but right now typically out of date thanks to impressive microcontrollers and FPGAs. It would be a disgrace to let them go to waste, so why not use them to make a neat 1980s-fashion computer system?
With this strategy in head, [Anders Nielsen] built the ABN6502: a single-board computer system centered on the venerable 6502 processor, but with comparatively fashionable interfaces like a VGA watch output, a PS/2 keyboard connector and even a wireless module to simplify firmware uploads from a Computer system. Just one style requirement was to reduce the range of new factors required the ordinary hacker interested in building the ABN6502 will almost certainly have a lot of of the chips lying around somewhere in their workshop.
The component record reads like a usual bill of elements for a 6502-dependent laptop, but comes with a ton of overall flexibility to permit for element subsititution. For the CPU, each the basic NMOS 6502 as very well as the modern day CMOS-dependent 65C02 are supported, along with their 6522 companion chip that presents I/O ports and timers. A ROM socket can hold either modern day, quickly flash chips or classic but sluggish UV-erasable EPROMs.
In its place of making use of DRAM chips with their complicated refresh requirements, [Anders] went for 32 KB of SRAM to put into practice the main memory unaffordable in the ’80s but effortlessly readily available nowadays. Regular 74xx sequence logic chips glue all the parts alongside one another, once again with many selections to add or eliminate functions as the user prefers. Pin headers carry out the I/O ports for easy connection to exterior peripherals.
The ABN6502’s software package library is at this time restricted to a bootloader, but a comprehensive progress toolchain primarily based on the CC65 compiler should really make it quick to establish all kinds of courses on this platform. We have already highlighted the intelligent wireless ROM flashing system, as perfectly as a demonstration of the 6502 driving RGB LEDs.