MacSE Technical Video Question

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Hello, all! Joined so I could post this.

I have a Macintosh SE with an aftermarket addition of a hard drive (I can pull identifying information from the back of the system if it's absolutely necessary, AND if someone tells me what they need). I'm guilty of having it for the sole purpose of someday making it into a Linux box Tongue It works (technically) but it is sans keyboard and mouse. I don't have much use for the current internals, as the 68k architecture (no offense meant) is *ahem* a little underpowered for any sort of modern computing.

I've recently decided that I was interested in knowing how the MacSE generates its video signals. I do not have an oscilloscope! -- so I'm asking you folks to help me out. I can't find much information online, as my Google-Fu is weak (old man) [for the less nerdy, that means I can't use a search engine very well at all]. I do gather that it's not something common, such as Composite signalling... but I can't find out any sort of technical info on what exactly it IS.

I do understand that there's a logic board and an "analog board" -- the latter being basically what drives the CRT directly, more akin to the PCB in a CRT monitor than any video card in a computer. I also understand that the MacSE display is a literal B&W display -- pixels are either 'on' (white) or 'off' (black) and there's no room for grayscale.

What I don't understand is the protocol of communication between the two boards. If someone could explain it to me (pictures will help! I'm visual) I'd be much obliged.

Thanks in advance.

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gsmcten's picture
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Re: MacSE Technical Video Question

starhawk,

Welcome to the site! Smile

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Steven (gsmcten)

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Re: MacSE Technical Video Question

Thanks!

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Re: MacSE Technical Video Question

Kinda disappointed that I haven't gotten my answer. I realize this is a techy question -- but I thought there would be plenty of techy people here who could answer it...

I'm still around, and I'll stay around, but I'm a little, well, disappointed.

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Re: MacSE Technical Video Question

Starhawk,

Patience...

If you ask it, they will come.

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Steven (gsmcten)

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Re: MacSE Technical Video Question

I'll be here.

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Re: MacSE Technical Video Question
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Steven (gsmcten)

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Re: MacSE Technical Video Question

Went through those links probably a little faster than you expected! The 68k MLA forum thread might help -- but I'm not registering over there to figure this out, simply because their registration process is about the clumsiest I've seen. I did it once here on applefritter (which has the same method) but I'm not doing it again if I don't have to.

Sorry, guys, no offense meant (really!) -- but there are better ways to eliminate spambots than manual activation via email. (ReCaptcha, anyone? It works pretty well, I hear!)

Sorry, but the other links don't have what I need...

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Re: MacSE Technical Video Question

Well...I tried.

I'm not that big of a Mac guy, but I do have a couple of SEs that I have been trying to cobble together.

My biggest disappointment is the Color Classic.
I have bought four of these things, supposededly working, but by the time they reach me they either no longer function, or require so many repairs that it is no longer dumping money into.

I'm sticking with my Apple IIs from now on.

Good hunting. Smile

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Steven (gsmcten)

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Re: MacSE Technical Video Question

Sorry for my earlier venting -- I get frustrated easily. Also... HTTP M404: Manners Not Found. Whoops!

Thank you for doing all that research. Even though, in the end, it did not prove fruitful, I do appreciate that you took the time to look all that stuff up for me.

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Re: MacSE Technical Video Question

Still here, still looking for answers... Sad

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Re: MacSE Technical Video Question

starhawk wrote:

Sorry, guys, no offense meant (really!) -- but there are better ways to eliminate spambots than manual activation via email. (ReCaptcha, anyone? It works pretty well, I hear!)

Not if the spammers are actually human. Which, in many cases these days, they are.

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Re: MacSE Technical Video Question

Wow, that's really special.

Any further info/comments on the video bit, or do I need to buy an o-scope?

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Re: MacSE Technical Video Question
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Re: MacSE Technical Video Question

No. You see, I'm not troubleshooting a broken Mac. I want to understand how the logic board communicates with the analog board.

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Re: MacSE Technical Video Question

Starhawk,

Sounds to me like you want a schematic so you can follow the functions between boards.
Or a written explanation of how they function together.
Is that what you are looking for?

Steven Smile

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Steven (gsmcten)

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Re: MacSE Technical Video Question

It's the signalling I'm after, what in somewhat more modern computers is called an "interface" -- what instructions are sent down the wires from the logic board to the analog board, how are they sent, and what each instruction does.

Just like RS-232 (ye olde IBM COM Port) or an ADB Port on the back of an older Mac or the 0-0.7v analog signalling and frequency transmissions through a VGA cable to a monitor, there is a pattern of some sort that constitutes information being sent across those wires. That pattern has to have SOME regularity and rules or guidelines to how it works. (Usually this is remarkably rigid as to what can and cannot go on.)

It's a bit like language -- I want to know how the two boards converse with each other.

Given the number and type of components on the analog board, though... I'd actually be rather surprised if the connection was anywhere near as sophisticated as I'm making it out to be.

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Re: MacSE Technical Video Question

Starhawk,

I'm sorry.
I personally cannot help you.
I do not currently have any sort of documentation that would cover what you are trying to find. I don't even have any links to cover that.

Does anyone else have some?

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Steven (gsmcten)

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Re: MacSE Technical Video Question

Crying

Help still wanted...

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Re: MacSE Technical Video Question

Still searching... Sad

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Re: MacSE Technical Video Question

Here's a nugget that might help direct you, found right here on AF:

http://www.applefritter.com/node/24198

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Re: MacSE Technical Video Question

OK, that's a little help -- that tells me that it's a /digital/ signal and not analog. I was hoping for that level of sophistication, but I was afraid that it was closer to VGA -- which is a 0.0-0.7v analog signal and very exacting frequency timings.

If this is /digital/ then that's good. I need to know voltage (my multimeter is analog, and I don't expect that to be helpful here) and then I can probably get a logic analyzer working with it.

I was fortunate to purchase a Stellaris Launchpad (low-power ARM-based microcontroller board) during the $5 promo price period -- someone has designed a simple logic analyzer program for it -- as long as it's not more than a 5v signal, I can use my Launchpad and their program as a logic analyzer... it's very basic, but it will do for now.

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Re: MacSE Technical Video Question

Still here. Had some Internet problems but they seem resolved for now.

Anyone can tell me the voltage on that signalling to the analog board, from the logic board?

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Re: MacSE Technical Video Question

...? Someone? Anyone? Beuller?

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Re: MacSE Technical Video Question

Starhawk,

I'm sorry.

I wish I could help, but I'm more of a II guy than a Mac guy.
That is not to say that I do not dabble with Mac's every once in a while and I do have an SE sitting in the other room, but since I have had nothing but bad luck with it I have set it aside for now.

I hope someone here has an answer that will help you.

Steven Smile

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Re: MacSE Technical Video Question

*shrug* if you (or anyone else) has the pinout(s) for whatever connector(s) go to the analog board, I guess I could stick a multimeter in there and take a look and find out for myself...

But then the pinouts would probably tell me voltages anyways!

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Re: MacSE Technical Video Question

Another thought.

Assuming this particular SE is stock inside in terms of CPU -- IIRC mine is an M5010 -- that would put it at a 68000 CPU running at a blazing 8MHz --

Could I run any sort of moderately decent Linux OS on this? I'd need to get an ADB mouse & keyboard somewhere, as I have neither... but on this board that shouldn't be too hard Tongue

I know there's the Linux/mac68k distro -- but they explicitly say "no stock 68000 CPUs need apply" which makes me Sad

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Re: MacSE Technical Video Question

Got brave and opened the case for the first time. Pulled the logic board (carefully!) -- there was a slight mishap with the speaker cable but nothing too significant, I just bent the connector pins and was able to bend them right back after getting the board out Wink

Noticing some interesting things on that board.

Reading from here, there should be the following chips on this board...

68000 CPU/Processor
8530 Serial Commms Controller (intended for a Z80 CPU)
6522 Versatile Interface Adapter (intended for a 6502 or similar CPU)
5380 SCSI Controller

My board has the following chips.
CPU -- MC68000P8 -- stock
SCC -- Z8530PC -- stock
SCSI -- AM5380 -- stock

But the 6522 is NOT a 6522! It's a 6523 Tri-Port Interface, second-sourced by Rockwell. What? (Amusingly enough, the chip label on the board still reads "VIA".)

Also -- I'm curious to know if I have an IWM or a SWIM. Here's the markings off that chip...
718 V H205V
VF4060-1PD
344-0043A

Oh... and the motherboard itself has a couple labels on it. One is silkscreened onto the board:
MACINTOSH SE
820-0176-B
1986
630-4125

The very yellow barcode label reads "M70109647".

Oh... this is the model of board with resistors for RAM determination. I'd say I've got 4mb, because R35 has one lead cut Wink Also, all four RAM slots are populated.

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Re: MacSE Technical Video Question

Decided against the idea I was playing with before. I'll be giving this Mac to a friend of mine, in the next few days; I know he'll take good care of it.

Sorry folks, that's how it goes sometimes.