Reverse Engineer the Spectre GCR?

JustG

JustG

New Tinkerer
Dec 12, 2021
65
17
8
California
With all of the amazing projects that have come out over the past few years for our old computers, has anyone considered or is there any effort to recreate the Spectre GCR cartridge? As Mac collector and now a ST owner, this is something that interests me:

en.wikipedia.org

Spectre GCR - Wikipedia

en.wikipedia.org en.wikipedia.org
 
Well, i've never seen the hardware in real life - but looking at this image, the layout looks simple - the question is, what's on the PAL (there's at least 1 there) and what are the other chips?

spectre-gcr.jpg
 
I'm now on a mission to find one of these. If I end up with one in my hands it's going to be sent to the right people.
 
mg.man said:
Indeed. It looks like Dave (Small) and team went to quite a bit of trouble to wipe off the chip markings. Here's the best I could pull off...
Click to expand...
Are those sanded or have they been painted over? it might be worth trying a little IPA on them

Edit: Looking at the pictures I would guess U8 is the only PAL on there, looking very closely at the picture @Kai Robinson posted I *Think* its marked as a TIBPAL16R4 so hopefully this is unprotected otherwise the equations would need to be recreated by hand
 
Last edited:
max1zzz said:
Are those sanded or have they been painted over?
Click to expand...
Sanded or acetone'd off. If you look closely at a few, you can see some sanding(?) marks in the corners of some of the chips.

There does seem to some trace of the original silkscreen on a few of the chips, hence all the different angles.
 
Worth a try, I've got an old programmer that still does all sorts of PALs. If we get one of those thingies my way I can give it a try (and take a look at manually recreating some code if it's locked)

Unless porchy wants to take a look, figured that might be easier from a shipping point of view.
 
I'm trying to price mine for sale. I won mine by guessing the birthdate of his son but also was a Magic Sac user. I spent a drinking evening with David Small after our mutual friends vouched for me. Lots of hacking stories exchanged
 

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I've got very little experience when it comes to ordering boards. I'm very interested in putting one of these together but I'd really need someone to hold my hand through the order process.
 
Hello Javier I can't follow the link were you able to download the bom and gerber for the magicsac

Tom
 
Did some research and it looks like the magic sac uses the macintosh 128k roms so they are 32k by 8 27c256 should work fine now to split a file

Tom
 
This is a schematic for the magic sac it has address lines at thru a14 so it supports 32k by 8 or 27256. Mac 128k or maybe mack 512k roms the parts are all common
 

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