Embedded {hardware} engineer and classic computing fanatic Ted Fried is again with the aftermarket modifications for computer systems lengthy since vanished from retailer cabinets — however this time it is a downgrade somewhat than an improve, turning the comparatively widespread Apple II into the purposeful equal of a uncommon Apple I.
Launched in 1976, the Apple Pc — which might later be generally known as the Apple I, to distinguish it from its successor — would spend little over a 12 months in manufacturing however had an outsized influence on the historical past of non-public computing. Created by Steve Wozniak and marketed by Steve Jobs, the Apple I — an eight-bit single-board laptop primarily based on the MOS Know-how 6502 processor — bought for $666.66 to an keen viewers, however its restricted manufacturing lifespan and a buyback program which noticed boards destroyed in change for a reduction on an Apple II imply working fashions are uncommon as hens’ enamel immediately.
It is potential to emulate an Apple I, in fact, however Fried determined to take a distinct strategy to experimenting with the machine which launched the Apple empire: downgrading the significantly extra widespread Apple II into its predecessor. “This venture makes use of [my] MCL65+ to transform an Apple II into an Apple I,” Fried explains. “The MCL65+ is a drop-in substitute the pc’s MOS 6502 which may emulate the microprocessor and far more.”
On this case, the MCL65+ — powered by a Teensy 4.1 improvement board — supplies each an emulated model of the MOS 6502 CPU which it replaces and the unique Apple I programmable read-only reminiscence (PROM) and RAM chips. “[These] include the well-known 256 byte Woz Monitor, 8kB of RAM, and some conversion routines for variations in video show and keyboard dealing with. All keyboard and video I/O are additionally echoed to the Teensy’s UART in order that code might be downloaded to the Apple I by merely slicing and pasting it right into a terminal program.”
The add-in board replaces the system’s authentic CPU, and provides every thing required to run Apple I code. (📷: Ted Fried)
That is removed from Fried’s first efforts at placing trendy {hardware} into classic methods. Late final month he unveiled the world’s first Motorola 68000-powered IBM PC, once more utilizing a Teensy 4.1-powered emulated CPU substitute, and final 12 months showcased the MCL64 Commodore 64 accelerator and MCL86jr FPGA-based IBM PCjr improve board.
Extra info on the Apple II to Apple I conversion is on the market on Fried’s web site, whereas the supply code has been revealed to GitHub underneath an open-source license.
