Macintosh 128k with SCSI port!!

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iamdigitalman's picture
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well, this guy is auctioning off a vintage 128k with all the trimings. I dont want to buy it, but I was curious how he got the SCSI port on the back. in the picture (unfortunanly it is one LOOOONG picture.) but it is the 2nd image of the back of the computer. you can clearly see that where the battery compartment was, there is a SCSI port that has been added. how was this done? I asked the guy how, but he is not the origonal owner. here is the image: http://homepage.mac.com/davidferrand/origanlmac2.jpg

and the auction:

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&rd=1&item=5173646180&ssPageName=STRK:MEWA:IT

enjoy!! -digital Wink

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tmtomh's picture
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Known Updrade, IIRC

IIRC this was an upgrade offered by one or more small companies at the time. Throughout the mid to late '80s, when there were still a number of pre-Mac Plus machines in service, companies offered SCSI and RAM upgrades for the 128s and 512s.

I'm sure there are many members here who could give much more detailed info on this.

Matt

iamdigitalman's picture
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Re: Known Updrade, IIRC

tmtomh wrote:

IIRC this was an upgrade offered by one or more small companies at the time. Throughout the mid to late '80s, when there were still a number of pre-Mac Plus machines in service, companies offered SCSI and RAM upgrades for the 128s and 512s.

I'm sure there are many members here who could give much more detailed info on this.

Matt

hey, I've never heard about it until now. Since this is the first pre plus machine with this hack/upgrade, That I have at least heard about, I thought I would bring it to the attention of the general public. I mean, it's not something you see everyday. But, I wonder, what happened to the RTC battery? thanks for shedding some light on it. anyone else have some infos? -digital Wink

coius's picture
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I remeber reading

about how the mac was created. The designers put in what they called a "utility slot" on the motherboard and told Job's that it can be used to diagnose problems with the Mainboard. I know Old Steve prob new what it was, but gave them the go ahead.
The designers figured that since the computer was a revolutionairy design, They needed to protect the costumers by giving them the ability to upgrade. (thus they added the port.)
And the rest was history... Tongue

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There is no utility slot on a

There is no utility slot on a 128k motherboard.

I have an early Mac 128k motherboard which has been upgraded to 4MB + SCSI. It still works fine. I think I was booting System 7.1 with it and running claris works. Here are the shots of the motherboard. This hack was not for the meek...

The job was to remove all the RAM, the RAM bus buffers, and add another address decoding pal. This is an early 128k motherboard. Later on apple made the 512k and 128k motherboards the same, except the 512k had some extra components by the keyboard connector.

Here are the pictures, they are large but worth it. One of a kind. Wink I call it the hot wired mac...

I don't think its rare. I guess I didn't know Apple Is were worth a ton either. I thought I'd be able to pick up one, but didn't want to spend over 1k. Wink

I have all the macintosh schematics as well as memos written by the mac team about an 8 bit 6809 mac with 64 k of ram and a very small screen. I'll put this up if anyone is remotely interested...

I've also replaced the processor in one of my mac boards with a brand new 68HC000. Works fine. This is the first step in creating a Macintosh computer kit, similar to the Replica 1.

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The RTC battery is behind the

The RTC battery is behind the connector. It still fits. There is a ribbon cable that is smashed between the case and the battery spot. The cable goes down to the header on the DigiSimmer board.

I'm confused why I can't find any information on this DigiSimmer board.

I've got 2 512k systems. One was upgraded to have an MFM hard drive (which I don't have) and one has MFM + 1MB. The guy on ebau didn't tell me it didn't come with the hard drive. Dude...

Anyway, I also met the owner of MacRescue who made an upgrade for the 512k. He was very nice and gave me the PAL logic equations for all the PALs on the mac except the ASG. I have not started to work on the ASG, but it is the last hurdle to make a Mac Kit.

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flashed ROMs eh?

Probably Plus ROM copies. Man what a big deal that was back in the day. Apple was having S-fits and cracked down on any and all who they caught making them. They were a pretty useful upgrade though, as they allowed one to boot directly from 800 disks or from the HD20 harddrive, along with numerous other improvements (including IIRC SCSI support.)

Cool pics logjam, glad to see something 'new' I hadn't seen before. You ought to do an article based on at least what you've already got up.

dan k

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About this ROM thing ...

So, the ROMs were replaced on your upgraded 128k? Was this strictly for the built-in HD20 functionality so you could use an 800k drive OR to provide the SCSI functionality, OR to exceed 512k RAM (or ALL of the above)?

Could you have theoretically upgraded to 4MB RAM without replacing thr ROM? The question arises as I have a 128k logic board which has had the original 128k's DRAM chips removed and replaced with sockets which were fitted with chips increasing the RAM to 512k. But the ROM is the original. So basically I have a 512k which can run the HD20 INIT to access 800k HFS drives. How far could I upgrade the RAM with this configuration, assuming I could find the chips for the sockets? Any ideas?

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re: About this ROM thing ...

Being as how Pluses are worth virtually nothing (except to those of us who love the old things!),
it'd be trivial to scarf the ROMs from a dumpster-Plus. Err, except if you've got a Plus logic board,
why not just use that intact LB in the 128K, it's a straightup dropin. Well, disregarding
the power supply issues of course. Tongue

My feeling on upgrading older 'puters, such as a 128K:

Don't bother, they're 'worth' more closer to their original form,
not just $$$, but as an historical experience. I mean, if you want
the functionality of a Plus, why not just get a Plus?

The original reasons for the upgrades were to bypass some of the
cost of a new computer (same as now!), but time has rendered that
rational meaningless.

OTOH, having a Mac such as logjam's, with such a cool and
convoluted period upgrade, that's got its own sort
of very interesting historical character.

BTW, 512K + Plus ROMs = 512Ke

dan k

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This slot business ...
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Of the 3 upgraded computers I

Of the 3 upgraded computers I have this is the only one with EPROM copies of plus roms. There isn't much different between the 128k and PLUS except for the ROMS, one PAL, and a SCSI chip. This 128k has 4MB ram, SCSI, mac plus roms, and boots from a 1.7GB hard drive. It can boot from a 800k disk drive with no problem.

I think its a little faster than a normal plus, it just feels that way. I met the person who designed the unitron Mac clone in south america and he sped up his 512k to the speed of a Classic by reworking the video logic equations. Who knows if this one is faster or if I am crazy...

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Could we get links or thumbna

Could we get links or thumbnails to those extraordinarily HUGE PICS! Wink It's hard enough to read on a 12" iBook anyway, let alone dealing with pic of that size that cause all sorts of trouble with the forums. Thanks. Smile

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How did you make those circui

How did you make those circuit boards?

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I design a schematic in WinQC

I design a schematic in WinQCad and then use the autorouter to eventually produce gerber files. I hand routed that particular card in Traxmaker and had the board manufactured by PCBexpress. You can use Eagle Cad for MacOSX to produce gerber files for PCBExpress.

PCBExpress will cut 2 108 square inch boards with the maximum dimension being 14" for $175. Smaller boards are cheaper, but the bigest bang for your buck is a larger board. You can create a large composite board of tiny boards and then saw them up later.

Right now I'm creating an Apple 1 casette card using the high resolution photographs and operating information. I should have the boards back by wednesday.

coius's picture
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wow!

I may know my slots, but you guys are amazing. Then again, I have never even taken a fundamental computer design class. (Hell, I don't even know how to figure how to do watt/ohm/voltage equations. (I spend my time on forums looking for the latest technogeek stuff. (like newest processor's performance, and the newest technology and how it will effect the way I will be dealing with it in my business when the stuff finally comes out.) I think I am a tab-A into Slot-B person. (and figuring out mechanics, and how to outfit my computers in a cool way W/O spending too much money (or any in fact))

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