Flashing HN27C4096 PLCC with TL866 II

Upgrade or replace the ROM.
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foft
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Joined: Mon Mar 28, 2022 12:20 pm

Flashing HN27C4096 PLCC with TL866 II

Post by foft »

I'm trying to program a new tos rom on my falcons, with lower access time. I grabbed some HN27C2096-10s from ebay. The TL866II software seems to support this.

I checked the PLCC44-DIP40 adaptor I got with the TL866II. It seems to match the pinouts from the data sheet as far as I can tell. Its the adaptor marked 78E/89C 51/52/58 SERCOND. I checked about 20 pins, but guess I should check all 44 to be sure!

The 'pin detect' fails. It seems to look for VSS to be connected (pin 12 and pin34). If I check the ic with a multimeter it shows they are not internally connected. Is that normal? Seems odd the burner software is checking this but the chip doesn't have them connected.

Anyway if I untick all these boxes I can hit read and read '0xff' everywhere. Which is either blank or .. just not working (presuming there are pull-ups in the burner)!

If I try to program it just says 'programming failed' with no other information whatsoever, which is helpful!

Anyway thought its probably a known thing, how to program these on TL866II, so thought I'd ask here if any has tried it and can help?
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DoG
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Re: Flashing HN27C4096 PLCC with TL866 II

Post by DoG »

Probably need two bodge wires on the adapter board. There is a few post about this on the forum and pics about the fix.
stephen_usher
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Re: Flashing HN27C4096 PLCC with TL866 II

Post by stephen_usher »

The PLCC 44 adapter boards are usually for PIC chips and not the EPROMs, I had to make my own adapter.
Intro retro computers since before they were retro...
ZX81->Spectrum->Memotech MTX->Sinclair QL->520STM->BBC Micro->TT030->PCs & Sun Workstations.
Added code to the MiNT kernel (still there the last time I checked) + put together MiNTOS.
Collection now with added Macs, Amigas, Suns and Acorns.
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DoG
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Re: Flashing HN27C4096 PLCC with TL866 II

Post by DoG »

Found another thread about this problem.
stephen_usher
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Re: Flashing HN27C4096 PLCC with TL866 II

Post by stephen_usher »

Yeah, I hacked together something and then later made a PCB. I should have some spares in the loft.

IMG_2103.jpg
IMG_2103.jpg (287.9 KiB) Viewed 199 times

I also shared it on PCBway: https://www.pcbway.com/project/sharepro ... Board.html
Intro retro computers since before they were retro...
ZX81->Spectrum->Memotech MTX->Sinclair QL->520STM->BBC Micro->TT030->PCs & Sun Workstations.
Added code to the MiNT kernel (still there the last time I checked) + put together MiNTOS.
Collection now with added Macs, Amigas, Suns and Acorns.
foft
Posts: 65
Joined: Mon Mar 28, 2022 12:20 pm

Re: Flashing HN27C4096 PLCC with TL866 II

Post by foft »

Many thanks!

So yes 40 pin->44 pin clearly there are 4 spare pins. The pins follow the same pattern as the adaptor.

However the adaptor has the middle pin NC on all sides.
The HN27C4096 has the middle pin NC on the top on the bottom, on the sides it is offset by one. So 13 and 33 are NC on the chip, while the adaptor expects 12 and 34 to be NC!

Spreadsheet of the pin mapping on the adaptor. Despite the clear answer I went through all 44 myself again this time :lol:

HN27C4096_adaptor_mapping.zip
(9.24 KiB) Downloaded 4 times
foft
Posts: 65
Joined: Mon Mar 28, 2022 12:20 pm

Re: Flashing HN27C4096 PLCC with TL866 II

Post by foft »

A quick note to say many thanks, this worked. Switching to the eprom allowed me to use the centurbo 1 evolution 3b bus speeder with 0 wait state rom.

Then I could repurpose the original 4.04 rom to the other falcon that only had 4.01...
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