27C400 EPROM emulators (beta) issue D technical discussion

General discussions or ideas about hardware.
cmorley
Posts: 291
Joined: Tue May 28, 2019 5:46 pm

Re: 27C400 EPROM emulators (beta) issue D technical discussion

Post by cmorley »

terriblefire wrote: Tue Jan 21, 2020 11:06 pm How are people wiring these up. I dont want to electro boom any.
For ones I am going to program infrequently I have just adapted a cable with pins and poke it into the plated holes.
Photo0895.jpg
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For a more permanent connection solder 0.1" headers and either use a PC motherboard USB A - header ready made cable or make one USB-dupont. Right angle headers if vertical space is an issue. You can fit them underneath - dupont connector will clear the SMT parts & should clear the ROM socket too - very neat wiring.

Or solder wires straight to the board.

The USB pinout is also the same as the cheap USB micro breakout PCBs you can get from eBay 10 for £0.99 delivered. e.g. Much cheapness USB adapters
4/5 pin female 0.1" headers are cheap too.

The issue D boards do have reverse polarity protection on the USB (issue C you'd short via the ESD protection on VBUS). I don't recommend abusing the reverse protection but it is there in case of a 180 degree plug error.
PaulJ_2.0
Posts: 571
Joined: Sat May 11, 2019 11:32 pm

Re: 27C400 EPROM emulators (beta) issue D technical discussion

Post by PaulJ_2.0 »

OK I made a 1m cable and it is fine on USB3. The longer cable continues to program garbage though so it can only be the cable.

Thanks for the link of those little converters, they will come in handy for plenty of things.
Squirrel61
Posts: 15
Joined: Wed Dec 18, 2019 5:22 pm

Re: 27C400 EPROM emulators (beta) issue D technical discussion

Post by Squirrel61 »

I'm using SmarTTY (thanks for the tip, Chris!) and my unit does program+verify in just under 8 secs. But when I put it in my A500, I got the three shades of grey and then a red screen, which means an error in the Kickstart ROM. So something probably went wrong. However, I had only 5 mins to test so I have to do some more extensive testing before jumping to conclusions.
cmorley
Posts: 291
Joined: Tue May 28, 2019 5:46 pm

Re: 27C400 EPROM emulators (beta) issue D technical discussion

Post by cmorley »

Make sure you byte swap the ROM image for an 68000 computer. They use the "wrong" endian ;).
Squirrel61
Posts: 15
Joined: Wed Dec 18, 2019 5:22 pm

Re: 27C400 EPROM emulators (beta) issue D technical discussion

Post by Squirrel61 »

Thanks. I know and I already took care of that. I think I'll do another verify against the source file, because I don't fully trust my USB-cable. It was ripped from an old keyboard and is longer and thinner than what I consider healthy, but it was good for program+verify anyway.
cmorley
Posts: 291
Joined: Tue May 28, 2019 5:46 pm

Re: 27C400 EPROM emulators (beta) issue D technical discussion

Post by cmorley »

What revision Amiga did you put it in. If it is a rev 3 or rev 5 you need to blob the /JEDEC solder jumper to change the pinout.
Squirrel61
Posts: 15
Joined: Wed Dec 18, 2019 5:22 pm

Re: 27C400 EPROM emulators (beta) issue D technical discussion

Post by Squirrel61 »

I know that, you clearly put that in the instructions. But it's a rev.6A board. As said, I only briefly tested it so it might well be that I did something wrong.

The funny thing is, when I powered it on I got the 3 shades of grey and after a while (because I didn't connect a floppy drive startup took longer) the red screen. After that, it was showing the red screen every time right after power on or reset. That's why I want to verify it against the source, to be sure that the "rom" contents haven't changed.

<edit> I just compared the "rom" contents and it is still 100% equal to what I programmed, so that is not the problem. Will have another go on the A500 board. Maybe it was not properly seated, because it was pretty hard to push it in.
cmorley
Posts: 291
Joined: Tue May 28, 2019 5:46 pm

Re: 27C400 EPROM emulators (beta) issue D technical discussion

Post by cmorley »

Squirrel61 wrote: Mon Feb 03, 2020 3:02 pm <edit> I just compared the "rom" contents and it is still 100% equal to what I programmed, so that is not the problem. Will have another go on the A500 board. Maybe it was not properly seated, because it was pretty hard to push it in.
Some boards were made with really poor quality single wipe sockets. Check what image you have selected as your default in the options menu. You can see what ROM is currently selected from the info "i" main menu option.
Squirrel61
Posts: 15
Joined: Wed Dec 18, 2019 5:22 pm

Re: 27C400 EPROM emulators (beta) issue D technical discussion

Post by Squirrel61 »

I did some more testing. I already programmed 4 kickstarts to the emulator, but so far only one because I hadn't wired up the rom selector. But after switching roms, it turned out that 3 out of 4 are working and just the one that is selected by default is redscreening. So I think something is wrong with the rom itself, although I read it from a working eprom. I will program a different rom in slot 1 and try again. And I will try the suspect rom file in UAE to make sure it is(n't) working.
terriblefire
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Re: 27C400 EPROM emulators (beta) issue D technical discussion

Post by terriblefire »

i got some microusb breakouts today in the mail. Will attempt to burn later.
———
"It is not necessarily a supply voltage at no load, but the amount of current it can provide when touched that
indicates how much hurting you shall receive."
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