Uncovering easter eggs in old Mac ROMs

The picture you see above is taken from the ROM of a Macintosh SE made in the  late 1980s. This black and white image remained buried inside old Macs until [Adam] and [Trammell] at NYC Resistor reverse engineered these old Mac ROMs and found a few really cool Easter eggs.

[Adam] and [Trammell] have been dumping ROMs from old computers for a while now. Their modus operandi is finding old 27C-series EPROMs on old computers, prying the out of their comfortable home, slapping them in a breadboard, and wiring up an Arduino clone to dump the data to a computer.

Recently, the guys found an old Mac SE lying on the side of a road in Brooklyn and brought it over to NYC Resistor. They had known about images hidden in the SE ROM, but the guys wanted to know how and where these pictures were stored. After carefully inspecting the binary file generated from dumping the ROM, [Adam] was able to recover three images hidden in every Macintosh SE.

The folks at Apple – especially in the heady days of the Apple II and 68k Macs – hid quite a few Easter eggs in the ROMs of their computers. For instance, the Apple IIgs has audio data stored in the ROM, and the Macintosh Classic hid an entire operating system – System 6.0.3 – in the ROM of the machine.

via Make

Hacking a parallel port flash memory programmer

[Pulko Mandy] doesn’t use his flash ROM programmer very often, but he does use it. When he tried to get support for a new chip and the manufacturer suggested he just buy a newer version he decided to hack the programmer and it’s software instead.

This device connects to the parallel port and was intended for use with MS-DOS systems (no wonder there’s no longer support from the company). The board uses logic chips to add read and write function. So the first step was to analyze how they connect together and come up with a set of commands. While at it he also made some changes to the board to bring the voltage more in spec and ensure the logic levels on the parallel port met the correct voltages.

His plan was to use the board with a Linux system so the parallel port interface can stay. He used what he learned from the hardware inspection to write his own interface in C++. It works with a chip he was able to use under the MS-DOS software, but he hasn’t gotten it to work with the chip that sparked this adventure. If you’re familiar with how the AT29C040A works please consider lending a hand.

Drop-in board for NES ROM chip makes cartridge reprogrammable

Here’s the guts from [Dext0rb's] Super Nintendo cartridge. It’s easy to pick out the dark-colored board which lets him reflash SNES ROMs via USB. We’ve seen this done a number of times, but this is a much cleaner option than hacks that just add a dead-bug-style memory chip.

The board he designed has a double-row of pin headers sized to fit the footprint vacated by the original ROM chip. The board has a mini-USB connector which can be accessed through a hole he cut in the side of the cartridge enclosure. This is in the right place so that you cannot plug it in when it’s being used in the SNES (which would cause damage). The ATmega32u4 chip handles USB connectivity and programs the 32 megabit flash chip which stores the ROM. He’s posted a few articles on the blog portion of his site which you’ll find interesting. We suggest starting with this hardware teaser.

Booting a 1989 Mac with Mario

As a new recruit to the 68k Macintosh Liberation Army, [dougg3] is really showing off his hardware hacking ability. He came up with a replacement ROM SIMM for his Mac IIci and made it play the Mario theme on boot instead of the normal chimes.

Swapping out the ROM in these old macs isn’t an uncommon procedure. On some 68k machines, there’s a SIMM slot to either replace or expand the soldered ROM. In fact, it’s fairly common to take the ROM SIMM out of a IIsi and put it in the king of kings computer to make an SE/30 32-bit clean. We’ve never seen a re-writable ROM SIMM for these old macs, so we’re pretty sure [dougg3] just spared a Mac IIsi from the dumpster.

Now that the entire 68k Liberation Army is clamoring for one of [dougg3]‘s re-writable ROMs (we’ve got cash), the question of what to do with it comes up. Of course, SE/30s can now be 32-bit clean without installing MODE32 and new startup chimes can be added. We’d really like to see some hard-core ROM hacking going on, like installing a 68060 in a Quadra 950.

[Read more...]

NES multi-cartridge

Here’s a mutlicartridge hack for the original NES that [Callan Brown] put together. He spent some time snooping around the signals on the circuit board seen above until he found the trace that maps the reset signal from the game console. This will be used to cycle through the various games stored on the cart’s memory chip. The ROM images that will be stored on this cartridge are concatenated, then burned to the EPROM. Since the donor cartridge (and the ROMs which were chosen) use memory managment, the hardware can be tricked into reading the ROM from a specific point in the EPROM.

The switching itself is handled by a 74HC161 binary counter chip. The reset signal from the on-board security chip acts as a clock trigger for the counter. Some clever wiring allows the output of the counter to select the starting address for the EPROM. Each time you press the reset button it increments the counter, thereby selecting a different ROM to load. See [Callan] demonstrate the finished hack in the video after the break.

[Read more...]

Gameboy ROM backups using an Arduino

gameboy_cart_reader

[Alex] collects retro gaming consoles. One day while playing a SNES title, his save games got wiped when he powered off the system. It turned out that the battery inside the game cartridge got disconnected somehow, and it got him thinking. He decided he wanted to find a way to back up his save games from the cartridges for safe keeping.

While cart readers exist, he says that they are hard to find nowadays, so he decided to construct his own using an Arduino. SNES cartridges are relatively complex, so he opted to focus on Gameboy cartridges for the time being. Before attempting to back up save games, he first chose to learn how to communicate with the cartridges in general, by reading the ROM.

He breaks the cartridges down in detail, discussing how they are constructed as well as how they can be addressed and read using the Arduino. He was ultimately successful, and offers up code as well as schematics on his site for any of you interested in doing the same. We imagine that save game reading (and perhaps editing) will likely happen in the near future.

Check out the video below to see his cart reader in action.

[Read more...]

GBA emulator ported to Didj

Tired of messing with the hardware of the Didj you picked up? Now you can use it for gaming on that last road trip of the summer. A Game Boy Advanced emulator has been ported for use on both the Didj and the Explorer. You’ll have to dig up a copy of the original bios for a GBA as well as some ROMs, but the rest seems pretty straight forward. We are still holding out hope for Doom or Quake on the Didj, but this will help us wait a bit longer.

[Thanks Nirvous via Rosincore]

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