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Early LaserWriter ROM dumps
Posted by: mcpublic on 2022-03-19 07:02:01
I've already looked and am pretty certain most of it was written in C
I just read Crispin Goswell’s 1987 paper “An Implementstion of PostScript.” Besides the fact that I believe you intrinsically, this reminder of the complexity of the language itself and the graphics algorithms leads me to concur. My “monkey’s uncle” statement was an inference based on the vast majority of early Macintosh apps being written in assembly language, and the mistaken assumption that the ROMs were “small.” From my memory of the MAME dump table: 64kB x 2 x 8 = 2MB. This is “big.” But the LaserWriter Plus also included a dozen fonts, right?
Posted by: NJRoadfan on 2022-03-20 17:13:07
PostScript being written in C makes sense. Adobe was selling the interpreter to vendors who would be using a variety of CPU architectures in their printers. The vast majority of early PostScript printers were 68k based, but that may have to do with maintaining compatibility with Apple's products. The early LaserWriter drivers were notorious for sending binary blobs of 68k machine language in the LaserPrep file to implement new printing features.

Running PostScript on a 300x300dpi printer with a 10Mhz 68k was never going to be fast even if it was written in pure ASM. It's a ton of pixels to rasterize for something made in 1985. Added overhead also comes from the fact that the LaserWriter driver does not completely convert all QuickDraw objects to PostScript routines. A lot of that heavy lifting is done in the printer by routines contained in the LaserPrep file.
Posted by: compu_85 on 2022-07-10 07:30:33
Attached are the ROMs from a LaserWriter IIG, v1.0 and 2.0.

The 1.0 ROMs are window'd EPROMs, the 2.0 are mask roms. There's a jumper on the board to select "2 MB" or "4 MB", the 1.0 roms are set for 2mb, 2.0 is set for 4mb.

-J
Posted by: compu_85 on 2022-07-10 07:55:24
Here's the firmware from a LaserWriter IIsc board, "Personal Laser" Version 1.0

** (c) Apple Computer, 1987 ** ** Hardware: Mike Flora ** ** Firmware: Tad Browne **
Posted by: compu_85 on 2022-07-10 08:23:04
And to the OP's first question, here are the ROMs from a LaserWriter (not Plus).

Hope that helps!

-J
Posted by: compu_85 on 2022-07-10 15:24:00
There's an error with the 2.0 ROMs I posted earlier... turns out these use 27C080's instead of 27C040's.

Now the 4M selection on the logic board makes more sense 🙂
Posted by: danda on 2022-07-21 06:18:52
And to the OP's first question, here are the ROMs from a LaserWriter (not Plus).

Hope that helps!

-J
That’s amazing! Thank you for sharing these!

I now really want to downgrade my LaserWriter (which was previously upgraded to a Plus). Any tips on how I should do this? I know a bit about hardware, but not about ROM dumping or burning. Is there modern EEPROMs that would be drop in replacements?
Posted by: compu_85 on 2022-07-21 16:03:32
Does your machine have erasable ROMs now? (little window under the sticker). If so you can just erase them and program in the older code.

Besides the extra fonts and bug fixes, are there any differences between the plus and original LW?

-J
Posted by: danda on 2022-07-22 00:05:56
Does your machine have erasable ROMs now? (little window under the sticker). If so you can just erase them and program in the older code.

Besides the extra fonts and bug fixes, are there any differences between the plus and original LW?

-J
I would assume it doesn’t have erasable ROMs. I’ve never looked at the controller board, but my assumption is that it was upgraded from an original to a Plus in the 80s, and never touched since. (I’ve had it 10 years now.) I’ll have a look this weekend though. If it’s not got erasable ROMs, so you know of any I could get that would be compatible?

I think it was just the extra fonts and an upgrade of PostScript that the Plus ROMs gave it. The reason I want to downgrade it is I have two machines - this one an original upgrades to a Plus (so the sticker on the back just says “LaserWriter”), and the other one was sold as a Plus. And I’d like to have them back to their original state, rather than just having two Pluses.
Posted by: danda on 2022-07-25 14:26:56
@compu_85 - do you have a pinout or datasheet of the LaserWriter/LaserWriter Plus ROMs? I can't seem to find any information about them.
Posted by: compu_85 on 2022-07-25 18:54:43
I dumped them as AM27C512's.

-J
Posted by: Sword7 on 2023-05-29 09:44:39
Ok, I now found this forum because I am new to this. I was searching for LaserWriter ROM dumps, etc. because they are based on HP LaserJet laser printers. Is that possible to make ROM dumps from HP LaserJet laser printers also? HP LaserJet printers use 68000 processor too.
Posted by: NJRoadfan on 2023-05-29 09:55:36
The HP LaserJet is NOT based on the LaserWriter. Both printers use the same Canon LBP-CX laser printer engine however.
Posted by: al kossow on 2023-05-29 10:27:55
It is possible to dump them. I've had an original LaserJet PCB for a while now that I've been meaning to dump.
The firmware is much smaller than Apples
Posted by: Sword7 on 2023-05-29 10:30:14
The HP LaserJet is NOT based on the LaserWriter. Both printers use the same Canon LBP-CX laser printer engine however.

Yeah. You are right. I read Wikipedia and it said that HP LaserJet is based on Canon LBP-CX engine.

I noticed that current MAME (/src/mame/apple/lwriter.cpp) still show skeleton flag. Are you trying to get it working?
Posted by: Sword7 on 2023-05-29 10:34:06
It is possible to dump them. I've had an original LaserJet PCB for a while now that I've been meaning to dump.
The firmware is much smaller than Apples

Yeah. I am looking for LaserJet ROM dumps because it uses PCL protocol for printouts and HP-GL protocol for plotter.
Posted by: Sword7 on 2023-06-02 16:04:12
I researched more. I now learned that LaserWriter II series use Canon SX engine. It is compatible with CX engine that I think so. LaserJet II and III are based on SX engine. LX engine is for personal laser printers like LaserWriter NT, LaserJet IIP and IIIP. LX/SX engine uses 68000 processor. I found postscript cartridges (ROM dumps) for LaserJet II and III printers but need PCL4 firmware dumps. I was looking for LX/SX service manuals but can't find them so far.

I found EX service manual (LaserJet 4 and LaserWriter Pro 600 series uses for 600-dpi printing), CLBP 360PS and 460PS service manuals (color laser printers - Color LaserWriter and Color LaserJet 4500 series). They can be implemented on MAME emulator but needs additional firmware ROM dumps. There are so many Canon service manuals for Laser and Inkjet printers.
Posted by: absurd_engineering on 2023-08-11 12:18:26
Howdy! Slight digression — I'm working on a LaserWriter IIg, specifically, trying to determine if there's code in the ROMs to support FPU operations if the empty 68882 socket were populated. I have images of the early and late ROMs, but I'm unsure of the interleaving scheme... any chance you have IIg ROMs already combined, or could instruct me in the use of your Go tool to combine them?

Thank you!
Posted by: al kossow on 2023-08-28 09:26:42
for the LW Plus completeists, there is an upgrade rom set on ebay that hasn't been dumped but I don't feel like spending $100 for it.
it looks like one with just higher density roms
www.ebay.com

Vintage Apple Macintosh Software LaserWriter Plus Kit OEM | eBay

Find many great new & used options and get the best deals for Vintage Apple Macintosh Software LaserWriter Plus Kit OEM at the best online prices at eBay! Free shipping for many products!
www.ebay.com
Posted by: danda on 2023-08-30 03:58:21
I saw that, but it's the actual upgrade kit - I'm trying to find the original non-plus ROMs. There was an upgrade kit on ebay in 2019 which had the original ROMs (presumably the owner had upgraded their LaserWriter, and then put the old ROMs in the box for safe-keeping) but they wouldn't ship it overseas so I didn't get it.
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