Producing a Functional Clone of the Apple Lisa 2/5, using NOS components.
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All ROMs used on the Apple Lisa Clone + some extras
Zip Archive - 36.83 kB - 08/23/2023 at 12:16
Yeahhhhh, I did say I'm not great at documentation.
But before I completely forget, here is a quick run down of things I found during building the Lisa.
1) On the CPU board by Warmech, there is a capacitor at C43. On an original Lisa, this was a capacitor that bridged over U5C. This capacitor is a 47pf ceramic through hole capacitor.
2) For some insane reason the keyboard interface needs a 3.3K pull *down* resistor, despite already having a 3.3K pull *up* resistor. I'm at a complete loss as to why this is needed, but alas it is needed. The keyboard interface only partially works if the 3.3K resistor pulling it to ground is missing.
3) Most 74S logic can be replaced with 74F logic - F logic is a lot easier to find, and a lot cheaper than S logic. I avoided HC and HCT logic like the plague - so use the wrong family as sparingly!
4) The 6309 PROMs can be replaced with 82S135 PROMs, or 82S147s - so long as you tell the programmer to treat the 82S147 like a 82S135! Alternatively, a W27C512 to 6309 adapter can be made, and has been proven to work. https://mastodon.social/@paulrickards/110984487600913906
5) gerbers for a 2mb ram card now exist! This has been built and tested in the clone - the Apple Lisa is now 100% not from Apple! It's also worth noting that there is a slight issue with the silkscreen - R1 and R2 are 33 ohm resistors. The resistor network at RP3-RP7 are 33 ohms, and are ISOLATED. I made a mistake and used bussed resistors, which didn't work at all. This is also a bit touchy about which TTL families are used, so definitely use the suggest 74S and 74LS ICs on the 2mb card.
Also the only RAM sticks that work are 256kb parity (either 9 or 3 chip sticks) at 12ns or quicker. 80ns will work, but then it'll crash after a few minutes. You sadly can't get away with loading two 1mb sticks in memory bank 1.
6) The ArduinoFile (profile emulator) has been tweaked/improved. The arduinofile now no longer errors out with a timeout issue, and has proven to be pretty damn reliable. It should also work in a Lisa 2/10 which has a quicker hard drive interface.
7) The Lisa LITE is only needed for 400K floppy drives. The LITE only generates a PWM signal from two other signals. The Floppy Emu and 800K drives (which can be used in place of a 400k drive - try it in your Macintosh 128/512k!) do not need this signal. Therefore a passive adapter can be used instead.
8) There is now a python script to split out a ArduinoFile Image so it can be mounted under Mini vMac. It can then recompile the drive image for the ArduinoFile. This makes copying Macintosh Files incredibly easy now:
It's a little bit funky, but it's incredibly effective.
9) A full Lisa can now be built from "only" 5 major boards (six including the COP adapter, seven including the external arduinofile):
COP Adapter Gerbers (bottom of the page):
CPU and RAM Card Gerbers:
Motherboard and IO Card Gerbers:
Front Panel PSU/Power Switch/Keyboard Interface:
(Note to self, get these on the Internet Archive with the ROMs.)
My gosh, this is going to be a short project log. Who would of thought it?
So with the realisation that the majority of the work had been done, the project was slightly condensed down to:
Designs from Alex:
Designs from Warmech:
Parts I already had available:
Other Purchased parts:
What I needed to build from Scratch:
Really, the entire project just boiled down to build a Motherboard, Power Supply, IO board and CPU board and some cable harnesses - then plug it all together.
From that, the following five boards were ordered from JLCPCB:
At a grand total of £190 in total for 25 boards shipped (minimum quantity of 5 each), it could be suggested that the boards came to a total of £8 per bare board. Extrapolating that out, a full Lisa would only cost about £48 for the core six blank boards!
Unfortunately, the RAM card wasn't as cheap at a cost of £75 (including shipping).
With all the boards on order, the Lisa project was fully underway.
This is definitely the "12 pages of waffle no one reads before the recipe", but I feel it gives much needed context to the origins - the primordial soup - of this project.
Two things really. The first is that I have basically accumulated every single hardware iteration of compact Macintosh that Apple had produced. My earliest is a 128K Macintosh that was built in the fifth week of 1984 (one week after the Macintosh was even launched!), with the latest being a Performa 200 from 1992 (the last black and white Macintosh Apple produced - it was just a rebadged Classic ii after all).
From that, I had an obvious gap in my collection - a Lisa.
In fact, I missed out on a Lisa before I even got into collecting Macintoshes. In about 2019 I found someone selling one, with a starting bid of only £30. I messaged the seller directly asking if they would accept an offer of £80. They declined, saying they would prefer to wait until the end of the auction.
The next day they had cancelled the auction and sold it to someone for £100. Their response was that the "other seller offered more".
No comment is necessary, as I am certain you can probably get the gist of my feelings that I managed to miss out on a Lisa by £20.
The next time I saw one for sale was for 2K in 2022, which for a badly paid engineer in their 20s was pretty much unattainable. Which really is the main reason for building a Lisa instead of buying one. They are incredibly expensive at the moment, a decent condition Lisa will sell for anywhere from £2K to £5K, basically a significant dent in my savings. I need to do a proper tally, but all told the Lisa has cost me about £500 in parts. Half of which was just the bare PCBs!
I had also - since at least the global event which we do not speak of - had a bit of an interest in building my own computers from scratch. I had already built a few RC2014 Z80 based computers, and I was considering building my own from scratch - but my main concern was getting it to do something useful.
I feel that the main death of a homebrew computer is that the person making it will always put the majority of their energy and effort into designing the hardware of the thing, before inevitably putting considerably less effort into the software. Most projects usually end in "I then got a monitor program running, so I considered it a working computer and left it to rust on a shelf for the next 20 years".
As such, I was adamant that any computer I build must have a good software library present.
Therefore I was set on building a clone of an existing computer - a computer from Apple no less, with a full 68000 and GUI.
I was set on building a Macintosh.
Yep. A Macintosh. I had found badly scanned schematics online, and I was fairly confident that the "Jecel" Unitron/Merlin PAL equations could be used.
Unfortunately, that proved to be the undoing of the entire project. It seems that once every five years of so, someone will find the badly drawn schematics of the Macintosh 128/512 and go "ah that doesn't look complicated!" And tries to build a clone of the Macintosh from scratch. Unfortunately it isn't that simple.
You see, a good chunk of the Macintosh is implemented in "Programmable Array Logic" - sort of like the great grandfather of CPLDs and FPGAs, they're generic logic that can be recombined internally by blowing fuses - like in Programmable ROMs. Sadly, it is borderline impossible to figure out how the internal fuses are arranged, once the security bit is blown.
This is because there are two types of PALs - combinational and registered. Combinational can be relatively easily decoded by just running through every combination of input possible once, and checking the output. As they usually only...Read more »
So... what have I managed to achieve here?
Let's begin with a quick bit of history.
As most people are aware, the Macintosh has been a series of computers that Apple has been selling since 1984 through to today. Originally, these had a really cute design - a small beige box, with a built in 9" Black and White CRT, with a solitary floppy drive as your only boot medium, running one of (but not the first by any stretch of the imagination) Graphical User Interfaces available to the public.
Inevitably progressed marched on, and features were added or evolved into the final flat slab of an iMac that we have today - obviously with some families of Macintosh deviating and evolving on their own, to create some fascinating examples such as the G4 cube, Xserves, 2013 "trash can" Mac Pro - including the ill fated and frankly weird Twentieth Anniversary Mac.
But what exactly came before?
Somewhere after the Apple ii (a series of cute 8 bit computers with a single logic board built into a keyboard) and before the Macintosh - whilst completely ignoring the Apple iii, because that was its own strange kettle of fish that was taking place at the same time - there was the Lisa.
The Lisa itself is similar in form factor to the Macintosh, with a similar concept. It used the same 680000 processor, integrated floppy drives, with a 12" Black and White CRT, running a very early Graphical User Interface (still not the first, as that was developed by Xerox, despite what some die hard apple fans will tell you). However, the Lisa is a very different beast to the Macintosh.
As you may of noticed, our expensive Fruit based computer of choice is the Apple Mac instead of the Apple Lisa. You may also of figured that the reason for this, is because the Lisa was a bit of an absolute flop. So much so that quite a few of the stock ended up in a landfill.
Mainly due to the high initial cost - it launched at retail for $9,995 in 1983, whilst the Mac launched at $2,495 in 1984 - brought on by the sheer complexity of the Lisa.
The "core" of the Lisa consists of four main boards. The CPU board which handles the CPU, ROMs, MMU (!), and the video generation. The IO Board handles the main peripherals like the floppy drive, keyboard, mouse, soft power, hard drive interface - all driven by a literal 6502, just to handle the peripherals. The ram boards (usually two for a total of 1mb) consists of at least 72 individual RAM ICs for 512k of RAM Plus Parity. Whilst the motherboard was a simple-ish backplane consisting of the card edge connectors and the connectors.
Compare this to the single logic board of the Macintosh, and you start to see the over engineering that went into the Lisa.
Despite being somewhat of a flop - Apple still managed to produce three distinct variants of the Lisa. The Lisa 1, Lisa 2/5 and the Lisa 2/10.
The hardware of the Lisa remained more or less similar throughout its production, however, the Lisa 1 is the most distinctive of the three - as it contains two 5.25 Fileware drives, that were also referred to as the "Twiggy" drives.
These disks held a fairly impressive for the time 851kb of data each, and were developed for the Lisa as well as Apple iii. In fact, some of the early Macintosh Prototypes that were given to developers used Twiggy drives as well!
The Lisa 1 is also able to use an external 5mb hard drive known as the "Profile", that was able to connect to the Lisa via the external parallel port connection.
Unfortunately, the Twiggy drives were notoriously unreliable. As such, the following iteration of the Lisa - the Lisa 2/5 - used the exact same 3.5" Sony drive that was being developed for use on the Macintosh 128K.
Realistically, the use of the 400K drive instead of the Twiggy drives was the only major hardware change from the Lisa 1 to the Lisa 2/5. The...Read more »
I have always been a bit terrible at writing essays. This is a trait of mine that has followed me through my History A level in sixth form, through report writing during my Robotics degree, and now onto writing Technical Descriptions for personal and work projects.
As such, I try to avoid writing paragraphs of text - as inevitably they become a grammatical and spelling mistake laden minefield that even spellchecker gives up in anger, mysterious punctuation straight out of "a pickle for the knowing ones" , unintelligible sentences that wouldn't go amiss in Vogon poetry, as well as explanations for technical concepts that could only possibly be brought on by a fascinating combination of sleep deprivation, a mild caffeine overdose, and my own brains attempt at throwing any sort of sentence out just so the bloody thing gets done.
As such, before my entire writing dissolves into some sort of grey gunge that you wouldn't particularly want to get on your shoes. I would like to give thanks to the following people:
To Alex and Will (AlexTheCat123, Warmech). Thank you so much for letting me use your board designs within this project. Without them this project would never have been completed so quickly, if at all.
Additionally, special thanks must go to Alex. Without your tireless support and feedback, I would never have been able to figure out some of the stranger problems I encountered. You are the Wozniak to my Jobs!
Spencer of RC2014 - thank you so much for the head start in ICs, and for letting me borrow your EPROM eraser, don't worry I haven't forgotten I still have it...
Thanks must also be given to John of Vintage Micros for the 512K Ram card. That saved me from soldering over 95 more ICs for this project.
Binary Dinosaurs - thank you for giving me a helping hand with some of the checks!
Compu85 - your information and resources were invaluable within this project. Thanks for answering some of my dumber questions when I asked them!
Riley, thank you for believing in this dumb project. I think we both are amazed this thing even works.
Bill, without inheriting your stubbornness and attention to detail, this thing would never of been built - let alone work. We're all going to miss you so much, Rest In Peace.
To all of my friends and family, thank you so much for coming along on this journey - it was a hell of a ride and I think we can all agree it's a near miracle that this thing even works as well as it does. I'm really sorry if I have missed anyone - I appreciate everybody who has helped me with this project. This has been the craziest and most ambitious project I have ever attempted.
Thank you all.
Now. I thoroughly suggest those reading about this project to grab a nice warm drink and get comfy.
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