Raped for it's enhanced chips.
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Looks like a complete un-Enhanced motherboard. The chips on there that are priceless if they work are the MMU and IOU. Pretty much everything else is available.
I can burn my own ROMs and I've got an extra Rockwel 65C02 or a W65C802 I could put in there... But I don't really need another //e... I just got two recently I didn't really need, but the price was too cheap to pass up. I probably should flip them. FWIW, one of the ones I aquired recently was un-Enhanced and I did what I was talking about before... except I put in a W65C02 in an adapter (can't plug those directly into a //e mobo). Used 28C64's for the EPROMs and a 2732 for the chargen.
Or do you mean you think someone bought that motherboard Enhanced and swapped out their un-Enhanced parts and is flipping the mobo? I suppose I could see that.
If you see the year 1984 in the top left of a iie motherboard, then it originally came enhanced.
I then look at the last 4 digits of the part number for the video ROM. Enhanced=0265. Unenhanced=0133.
Look to see if the part numbers by the chips match those printed on the board itself.
The only good thing about that board is the keyboard ROM. On an enhanced motherboard it's a revision D. On the unenhanced motherboard, it's a revision B.
The only way to restore that motherboard is to enhance it with original Apple chips. But using EPROMS is what most people do. That motherboard did not even get that courtesy.
Thread brings up a point, the value of the IOU/MMU are golden. I know of no replacements yet. So cannibalizing another board/system to keep your pride'n'joy working is the only option. Surely they can be recreated in FPGA, at worst an FPGA on a tiny board that fits the socket. But til that happens best keep a few tested donor boards on-hand. And I do just that - even though those parts appear to be reliable.
I didn't remember exactly when the changeover to Enhanced was. And I don't have the part numbers memorized, I'd have to look that up.
There really isn't much value in originality of //e motherboards. Whether they have the original ROMs or EPROMs, either way... Apple made like 10 million //e or something, so we'll all be long turned to dust before they are ever crazily valuable like an Apple-1 or anything. Probably at least long dead before they become valuable like a Rev 0 ][.
Is there really a big advantage of the Rev D keyboard ROM? I've enhanced a few //e in the past and I never bothered changing out that chip. I just do the two ROMs and the VIDEO chip. The last one I did I used AT28C64 EEPROMS because I had them on hand. They worked great. I had a 27C32 for the VIDEO, also not an issue. The original Apple chips are great if you can find them but as has been said, the only real place to do so is to rob them from another //e motherboard. If there were any stashes of NOS parts they've probably long since been depleted or some crazy collector has them and they'll never see the light of day on the market.
I suspect that someone bought this board to fix their //e and then they backfilled it with their old un-Enhanced parts to sell it. Nothing really wrong with that. For that matter, someone may have a reason to want an un-Enhanced machine. I remember there were a few programs which ran on the un-Enhanced that wouldn't work on an Enhanced //e or a //c back in the day, and a few others that just looked weird due to the Moustext characters. Anyway, if I needed another //e motherboard, it wouldn't bother me that much, I'd just do the same thing to this one that I did the other //e I got recently and call it good. I've got a spare Platinum //e motherboard that is complete and working and a spare regular //e board that is missing either the IOU or MMU, I don't remember. I don't remember if it is un-Enhanced or Enhanced even. It's in a box upstairs somewhere. It came with a bunch of leftover parts someone gave me.
I just dug my extra spare //e motherboard out. It is missing the 65C02 as well as the MMU... but it has the Enhanced CD and EF ROMs and VIDEO ROMs- original Apple parts. The Keyboard ROM, as noted for most upraded motherboard is the original un-Enhanced one.
So if I boiught that mono off eBay I could make one complete "properly" enhanced machine since I have an extra Rockwell 6503 (65C02) which came out of a different //e.
What would be the difference between these "B" and "D" versions of the keyboard rom? And why is one better than the other?
That's what I was asking. I've got //e that came originally un-Enhanced with the old Keyboard ROM and ones that came Enhanced with the new one... and honestly I can't really tell any difference. The keyboards work the same either way as far as I know.
They were updates to the Dvorak keyboard layout.
Oh, didn't you know the Apple //e had an optional Dvorak keyboard layout? No? AFAIK, Apple didn't officially document it until the late 90's.
According to hackers who compared the contents of different revisoins of the keyboard ROMs (eg: James Sather) Apple shipped the //e with a preliminary version of the Dvorak layout, then updated the ROM when an official Dvorak American Simplified Keyboard Layout was published.
Are you wondering why Apple bothered maintaining the //e's Dvorak keyboard layout if they didn't officially document it?
Maybe they didn't want to acknowledge that they'd screwed up the circuitry: you could enable Dvorak capability by modifying two traces labeled X1 and X2, but then you also had to enter a POKE command to actually switch to the Dvorak keyboard. It would revert to QWERTY every time you reset the computer, which was pretty awkward. But, worse still, it had a design error that would disable all video whenever you switched to Dvorak. Oops!
In 1998, Apple finally published this technote on how to switch the Apple //e between QWERTY/Dvorak. It reveals all the horrible flaws with their implementation...and includes a warning that it "may void your warranty"!! (Dry humor, maybe?)
Here's an excerpt from Apple's technote that illustrates how badly they'd bungled the Dvorak feature on the Apple //e. It's never good to instruct users to remove chips and bend pins...
Well, since I've got no interest in DVORAK keyboards... probably a non-issue.
Good information to know. Never underesitmate the value of trivia like this. It'll be interesting (if not amusing) to read that tech note.
Here's another related anecdote from Wikipedia:
The Apple IIe had a keyboard ROM that translated keystrokes into characters. The ROM contained both QWERTY and Dvorak layouts, but the QWERTY layout was enabled by default. A modification could be made and was reversible and did no damage. By flipping a switch, the user could switch from one layout to the other. This modification was entirely unofficial but was inadvertently demonstrated at the 1984 Comdex show, in Las Vegas, by an Apple employee whose mission was to demonstrate Apple Logo II (programming language). The employee had become accustomed to the Dvorak layout and brought the necessary parts to the show, installed them in a demo machine, then did his Logo demo. Viewers, curious that he always reached behind the machine before and after allowing other people to type, asked him about the modification. He spent as much time explaining the Dvorak keyboard as explaining Logo.