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| LaserWriter 810 Pro ROM | |
| Posted by: Dandu on 2019-12-21 07:29:56 I search a specific things, can you help me ? I search a ROM dump from the LaserWriter 810 Pro. Actually, i have found many pages with reference to an easter egg with this printer, and i will verify that... and i must find the ROM. I have not found a printer to make the dump. My article about that : https://www.journaldulapin.com/2019/04/20/pizza-burrito-imprimante/ (in french) There is information about that on this pages : http://www.mackido.com/EasterEggs/LaserWriters.html https://news.ycombinator.com/item?id=13439752 https://en.everybodywiki.com/Stump_the_Experts | |
| Posted by: Dandu on 2021-01-07 08:26:52 One year later, no one ? | |
| Posted by: NJRoadfan on 2021-01-09 08:13:43 I can't imagine Apple sold too many of these. Whatever was in service was likely scrapped at this point. | |
| Posted by: danda on 2021-01-30 09:00:23 User /u/royalmailpostpak on reddit pointed out that there's a LaserWriter Pro 810 for sale in Italy at the moment. | |
| Posted by: Dandu on 2022-01-21 16:04:02 I have an update (and a problem) : i have buy a card with the ROM, i have dump the ROM (many chips) and i can't use it. I think the ROM chip are interleaved, but i don't know how. I search the postscript into it (if there is a postscript inside 😀 Can you help me ? It's the 4 chips : http://down.dandu.be/printer.zip (and a photo : http://down.dandu.be/printer.jpg) | |
| Posted by: cheesestraws on 2022-01-22 03:16:26 What kind of EPROM are they? | |
| Posted by: Dandu on 2022-01-22 03:32:31 AM27C040. Actually, the checksum is on the stickers and i have the right value. | |
| Posted by: dougg3 on 2022-01-22 11:31:44 Ahh, good call on the checksums. I didn't even realize they were checksums. These files look really weird to me. I tried interleaving them myself, but I don't see anything close to human readable. I would have expected some Apple copyright text in there or something. I guess there doesn't have to be human-readable text, but it seems like there would be something that binwalk would recognize. binwalk seems to think that the entire file (until you get to the part with all FF) has a pretty constant entropy around 0.6. I'm not sure what that means... Is it possible that they've remapped data pins and/or address pins a little bit in order to "encrypt" the contents? It would be interesting to trace the pins back to where they go on the microcontroller or processor or whatever is in control. | |
| Posted by: NJRoadfan on 2022-01-22 11:47:17 It could also be a compressed firmware image if the printer has a bit of RAM on it to decompress. | |
| Posted by: cheesestraws on 2022-01-22 12:01:42 I had a brief look earlier trying to get a copyright notice out with a couple of unorthodox bit orders (reversed bits, reversed nybbles) but I couldn't see one. Though I couldn't test interleaving, mostly because I ran out of time. | |
| Posted by: Dandu on 2022-01-23 15:28:25 Actually, there is two other chip with "data/rom" on the sticker, but i can't dump it now : the chip is not the same and my adapter cannot dump it. And dougg3, for the checksum, the first time, i have not seen that. But when i have made a second dump to be sure, i have seen the value and "tilt" : it's the same value ! I will try to dump the two other chip with a friend. And it'w very complicated to try to understand the code : it's not a 68000 based printer like the first LaserWriter, it's a Weitek 8200, a RISC CPU (PA RISC, i mean, but i'm not sure) | |
Posted by: cheesestraws on 2022-01-24 07:38:33it's a Weitek 8200, a RISC CPU I've got a NuBUS RIP with one of those on. They were quite popular. I seem to remember finding quite a bit of documentation out there when I looked to see if I could use it as a more general coprocessor | |
| Posted by: Dandu on 2022-02-03 05:45:46 A friend dump the two others chip for me and... YES ! http://down.dandu.be/ROMcostena.bin It was true : there is an easter egg about burrito on the ROM ! (there is many text string about the restaurant, the burrito, etc.) Next step : i will try to extract the text (i suppose it's a postcript text, but i'm not sure) ti see the original page | |
| Posted by: dougg3 on 2022-02-03 21:15:34 That's way too cool! I wonder if binwalk knows how to detect PostScript files... | |
| Posted by: chi100 on 2022-02-15 11:12:41 It looks ROMcostena.bin is the ROM of the Ethernet board and not the printer mainboard. What CPU does the Ethernet board use? | |
| Posted by: chi100 on 2022-02-15 11:18:06 Or actually maybe those aren't the ROMs of Ethernet board. I see two other ROM looking things in a picture. Can you post a picture of the ROMs that you dumped? | |
| Posted by: chi100 on 2022-02-15 18:38:56 I took a closer look at the situation. The Weitek 8200 is a Harvard architecture so the code and data live in different address spaces. This means the 4 ROMs you posted first are the code and the second ROM is probably the data. There's a rough disassembler here: https://github.com/jrmuizel/weitek-8200-disasm/ that seems to work on the code ROMs. | |
Posted by: cheesestraws on 2022-02-16 16:28:15There's a rough disassembler here: https://github.com/jrmuizel/weitek-8200-disasm/ that seems to work on the code ROMs. Thankyou for the link to this! If I ever get around to playing with my 8200 board that will be helpful. | |
| Posted by: Dandu on 2022-02-18 02:36:42 Hi Thank you ! It's note the ROM from Ethernet board (i have dumped the ROM too). I have annoted a photo.  | |
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