Introduction: Create Macintosh Plus ROMs

This Instructable will guide you through the process of "ripping" EPROM images from from your Macintosh Plus ROM chips and (or) "burning" the images to new chips. The appendage will basically be performed double to create both "hi" and "lo" ROM chips for your Mac Plus.

This documentation has the following applications:

  • Create replacement ROM chips / infrequent Read-only storage chips
  • Choke present Beaver State uncomparable ROM chips
  • Betray ROM chips online

I created this Instructable after characteristic bad ROMs as the root cause of a very peculiar error on my Macintosh Plus.

This guide is also applicative to Macintosh 128K and Macintosh 512(k,e).

Supplies

You must have the following supplies on hand in order to proceed:

  1. TL866 or TL866II, or TL866II+ (Amazon)
  2. Access to a Windows PC (Linux & MacOS supported but not shown in this guide)
  3. At to the lowest degree 2x 27C512 28DIP chips (eBay) (Aliexpress)
  4. Mack ROM chips (Optional)
  5. Macintosh ROM Paradigm files (Semi-optional)

Step 1: Rent ROM WHA?

Let's talk about "ripping" ROM images from physical chips. For simplicity sake I will describe the process of ripping ROM images on Windows, as it is the virtually straight forward serve with the TL866II+. However, information technology is possible on Linux and Mac OS with Thomas More endeavour.

It should be noted that this guide will non cover how to physically uninstall or install your ROM chips but please interpret remotion and installation of Read-only memory chips should represent a tender process. If the metal pins are damage your Read-only storage chip may become an interesting piece of trash.

What is a "ROM" chip?

Happening the technical side, ROM is "Read Only Memory" — ii physical computer chips installed on your Macintosh Plus system of logic board which issue commands to the Central processing unit. The memory in the Fixed storage chips is programmed to issue primary book of instructions like loading the operational system from the hard drive and much, much more.

What does it mean to "rip" a ROM prototype?

Cacophonic ROM is the process of interpretation all of the ROM chip memory to your computer. You will postulate an image of an existing working ROM in order to produce recent replacement chips. If you don't take in working ROM chips or would prefer to download a re-create, you give the axe find many an popular ROMs registered on the "Macintosh Repository" site — a great resource for the community (Direct Download link). I also host ROMs which I pulled from my own chips in GitHub, which you posterior find linked in the next section.

When the term "visualise" is used you seat metaphorically imagine a "shot" of the entire ROM chip memory. You can consider the work on like a photocopy. When we make over the copy of the ROM cow chip memory using the TL866II+ programmer it is called "ripping".

How do I rip a ROM image?

Begin away downloading the expedient Windows software program for your TL866II+. If you purchased the TL866II+ factory-made by the party available from Amazon and linked to in the supplies section then you can download the software you need from present on the Autoelectric website.

Step 2: Information technology's Ripping Time!

Once you hold the package you motivation for your TL866II+ (or TL866 / TL866II) and you have confirmed your programmer is detected then you crapper proceed with reading or "ripping" ROM images from some of your ROM chips, which is dabbled in this step.

Screenshots in this section will illustrate the software for the TL866II+ but IT is very comparable for early models.

Ensure your device is detected

For whatever reason your system may non play nice with drivers and software program. When you open the coder computer software in Windows ensure you see the message "1 Programmer Engaged".

Select Your Cow chip

The TL866II+ totes support for over 15000 chips! Amazing! But... not important right like a sho; we only need to support i type of chip; the "AM27C512 @DIP28". Don't disjointed the "AM27C512 @DIP28" for the "AM27512" — one has a "C" and one does not.

  1. Disable the options "Pin Find" and "Ensure ID" from the lower left corner
  2. Click the "READ" clitoris near the clear or select "Device" -> "Register" from the card block u.
  3. Click "Register" on the subsequent pop-fly.
  4. Use the ~5 seconds the programmer takes to read your ROM chip to reflect on how neat this is.
  5. Voila! You have a ROM image... letter-perfect? Maybe?

Verifying the ROM image

To start, you should not see a varlet full of "FF" — if you did past you either inserted your chip incorrectly or your Read-only memory chip is dead. Information technology's also practicable that you selected the wrong chip, in which case you should reflect on your mistake earlier correcting it. I bear attached a screenshot of a unexpired Read-only memory chip; yours may vary depending on the rom edition Beaver State image you're using.

If you get laid the version of ROM you have (there are A, B, and C where "C" is the newest for the Mac Plus) then you tin can only compare the look-alike to a Read-only storage downloaded from the Macintosh Repository. I have also provided my own ROM images, set-apart into "hi" and "lo", which are available on my GitHub.

Save your ROM mental image

Simply get across the save button or blue-ribbon "File" -> "SAVE" from the menu and save the output to a memorable location on your computer; you volition need this file to burn to a new chip.

Repeat the process delineate in this step for some of your ROM chips.

Step 3: Burning ROMs

On fire a ROM bu means "writing" the ROM image we ripped from your chips or downloaded to fresh chips. If you didn't crosscurrent a ROM image from your cow chip you can find the images on my Github as well as connected the Macintosh Repository here.

Programmer Software program Changes

  1. Click "Select IC" at the top or click "Select National Intelligence Community" -> "Search & Select" in the menu and past shift the chip to "AM27C512 @DIP28".
  2. If you don't have the ROM image in your programmer from the early steps, simply click the "OPEN" button at the top or "File" -> "Open" in the carte du jour and select the first of the two images you saved in the old step or the appropriate ROM files downloaded from Macintosh Depository.
    • If you are using the ROM files from Macintosh Depository there are extra steps which will not be moss-grown in the immediate release of this Instructable.
  3. Click "PROG" at the top or "Gimmick" -> "Program" from the fare and "Program" on the following screen.
  4. Repeat this process for both the "hi" and "lo" ROM chips.

That was it! You can load Beaver State "rip" the Read-only storage image from the recently chip and verify it against the ROM image you loaded into your coder or merely re-install it back into your Macintosh Plus and execute a test boot.

With this recently process you tail end help our friends surgery even sell ROM chips!

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