Laser 128 ROM dumper

This dumps the ROM from a Laser 128 while the system is live. Useful if you don't have an EEPROM programmer/reader of your own.

This utility will work on both "old" and "new" model Laser 128s, but the ROM map is quite different, so you must tell the tool which model you have.

On the "old" models, you will need to manually toggle between Parallel and Serial to get both versions of the slot 1 ROM. You will be prompted to do this.

On the "new" models, you should leave the switch in the Parallel position the whole time, otherwise you will get two copies of the serial option ROM and zero copies of the parallel option ROM. You must also ensure that slot 5 and 7 are set to Internal, or you will be dumping the ROMs from your attached cards (or random electrical noise).

Accuracy / known issues

Output is correct for ROM version 2.9 (on an old model) and ROM version 6.0 (on a new model).

The only part of this I don't quite understand is that 16 bytes from slot 1 don't end up matching the original ROM. They should be all $FF, but there is an odd pattern there instead. The tool manually rewrites it. I suspect it is either (a) some convoluted logic with the Parallel/Serial switch or (b) something to do with the port configuration you can set by holding "P" while powering up the machine.

ROM layout

The first 16KB of the ROM (regardless of old vs. new) is just directly mapped to C000-FFFF ROM. INTCXROMON must be enabled to access Cxxx, of course. This is the same as the CF ROM of a Platinum IIe, or CD+EF ROMs concatenated from an earlier IIe.

The second 16KB of the ROM contains slot and option ROM for the built-in peripherals. The exact mapping varies between the two models.

"Old" Laser 128

0000 - 00FF = empty (reserved for soft switches)
0100 - 0FFF = C100-CFFF (INTCXROMON)
1000 - 3FFF = D000-FFFF ROM
4000 - 40FF = empty (reserved for soft switches)
4100 - 42FF = C100-C2FF (INTCXROMOFF, Parallel mode)
4300 - 43FF = empty (no ROM for slot 3)
4400 - 44FF = C400-C4FF (INTCXROMOFF)
4500 - 45FF = empty (slot 5 is always external)
4600 - 46FF = C600-C6FF (INTCXROMOFF)
4700 - 47FF = empty (slot 7 is always external)
4800 - 4FFF = C800-CFFF Slot 1 option ROM (INTCXROMOFF)
5000 - 50FF = empty (reserved for soft switches)
5100 - 51FF = C100-C2FF (INTCXROMOFF, Serial mode)
5200 - 57FF = empty (no alternate slot 2-7)
5800 - 5FFF = C800-CFFF Slot 2 option ROM
6000 - 67FF = empty (inaccessible?)
6800 - 6FFF = CC00-CFFF Slot 6 option ROM bank 1
7000 - 77FF = empty (inaccessible?)
7800 - 7FFF = C800-CFFF Slot 6 option ROM bank 2

Slot 6 option ROM bank 2 is empty in ROM 2.9, but it might be populated on other models. I've confirmed that it's accessible.

"New" Laser 128 (also EX and EX/2)

0000 - 00FF = empty (reserved for soft switches)
0100 - 0FFF = C100-CFFF (INTCXROMON)
1000 - 3FFF = D000-FFFF ROM
4000 - 40FF = empty (reserved for soft switches)
4100 - 47FF = C100-C7FF (INTCXROMOFF, SLOTC3ROMON)
4800 - 4FFF = C800-CFFF Slot 1 option ROM (INTCXROMOFF)
5000 - 57FF = C800-CFFF Slot 5 option ROM
5800 - 5FFF = C800-CFFF Slot 2 option ROM
6000 - 63FF = CC00-CFFF Slot 7 option ROM bank 1
6400 - 67FF = CC00-CFFF Slot 7 option ROM bank 2
6800 - 6BFF = CC00-CFFF Slot 7 option ROM bank 3
6C00 - 6FFF = CC00-CFFF Slot 7 option ROM bank 4
7000 - 73FF = CC00-CFFF Slot 7 option ROM bank 5
7400 - 77FF = CC00-CFFF Slot 7 option ROM bank 6
7800 - 7FFF = C800-CFFF Slot 6 option ROM / CC00-CFFF Slot 7 option ROM bank 7+8

There's an overlap because the slot 7 banking register uses 3 bits, which gives you 8 banks, but they only use 6. The other two really belong to the slot 6 option ROM. C800-CBFF for slot 7 is actually RAM dedicated to the disk controller.

License

Copyright 2021 Renee Harke

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