Thanks for the clue.I do not know, if it helps, but in this thread (last post) there is another adapter (for one 27C010):
Macintosh SE broken ROM LOW chip
Hi all, I have a Mac SE showing a barcode-like pattern: A friend of mine has the same computer, so we swapped parts until we found the culprit: the 342-0353-A (rom low) chip. I got the BIN image on the web (64 kB), but I don't know if I can use a 27c512 eprom as direct replacement or not; do...forum.vcfed.org
There are two 4.7kOhm Resistors used to connect the 5V to VPP, PGM and OE.
I think that this is used in the same way in the above adapter.
Macintosh SE EEPROM to ROM adapter
- Thread starter Kai Robinson
- Start date
I'll definitely look into that option. Thanks!
Has anyone successfully replicated the HI/LO roms using this adapter? Also, was the value of the resistor network (RN1) ever determined?
As mentioned before, Kai doesn't browse this forum anymore, from what we know, so you sadly won't be likely to find the answer here. He's active over on https://tinkerdifferent.com, so it might be best to try and contact him there, or to start a thread about it.
Thank you. My boards should be here this week. My plan is to test the boards this weekend.
I built a few of these last night and couldnt get them to work. All I get is a garbled screen. I tried several different values for the resistor arrays, same result. I know the EPROMS are good because they work in a modified socket I made. Has anyone implemented this solution successfully? If so, I am all for some pointers.
I can't use these gerbers in their current form. I found out the hard way:
Impossible to upgrade the ROM and SWIM at the same time - which is the only reason you would ever want to upgrade the ROM in the first place. You could use some really tall pins so they miss each other, but then you interfere with whatever's in the PDS slot - and an SE with something in the PDS slot is a better upgrade candidate than one without.
Impossible to upgrade the ROM and SWIM at the same time - which is the only reason you would ever want to upgrade the ROM in the first place. You could use some really tall pins so they miss each other, but then you interfere with whatever's in the PDS slot - and an SE with something in the PDS slot is a better upgrade candidate than one without.
I pulled it off but they really suck to solder. Very very tight spacing and PLCC SMD shenanigans.
I'm not sure how to make it less painful to build these adapters because they're sorely needed not just on computers but arcade games as well. Maybe some new design with a crazy 2-3 layer sandwich of thin PCBs that gets soldered together?
I'm not sure how to make it less painful to build these adapters because they're sorely needed not just on computers but arcade games as well. Maybe some new design with a crazy 2-3 layer sandwich of thin PCBs that gets soldered together?
Hello all,
I too built an adaptor based on the gerbers posted here. It doesn't work unfortunately.
Looking into it, the reason is that the 8 data bus lines are tied together between the HIGH and LOW ROM chips on the adaptor board. The SE uses a 16 bit data bus and with the HIGH/LOW interleave and a common CS line on the motherboard we need the data bus lines to be independent as the motherboard assigns them to the high and low byte respectively of the CPU data bus.
For what it's worth, the adaptor does work one chip at a time. I can verify it against the mask ROMs (one of mine has a couple of errors).
I will prepare "fixed" gerbers for those who want to use DIP 27C010s... anyone let me know if you need a board and once I test them I can maybe post some out.
I too built an adaptor based on the gerbers posted here. It doesn't work unfortunately.
Looking into it, the reason is that the 8 data bus lines are tied together between the HIGH and LOW ROM chips on the adaptor board. The SE uses a 16 bit data bus and with the HIGH/LOW interleave and a common CS line on the motherboard we need the data bus lines to be independent as the motherboard assigns them to the high and low byte respectively of the CPU data bus.
For what it's worth, the adaptor does work one chip at a time. I can verify it against the mask ROMs (one of mine has a couple of errors).
I will prepare "fixed" gerbers for those who want to use DIP 27C010s... anyone let me know if you need a board and once I test them I can maybe post some out.
