Hi all
Just wanted to contribute to the knowledge base!! I've been looking for an EPROM programmer for a while. I've been using various sources (including Paul) for roms for a while, but got to the point where I felt that a programmer of my own was the way to go. I decided on a top853. They're £25 ish from eBay. Add on a uv EPROM eraser for £9 and away we go! Well, at least so I thought!!
My project was to "upgrade" my addams roms to addams gold. First off I needed an extra rom. I found one in a box of old kit. Ideal!!
Tried to burn one....error. Damn! Erased, tried again. Error!! Damn damn!!
A bit of googling revealed that the usb programmers frequently struggle with 27 series EPROMs as they program at 12v ish. The 5v, 500ma is stepped up but often isn't enough to write reliably. Google told me that if I were to crack the case open I'd find a non populated power plug to supply a juicier 5v supply. Out came the soldering iron and I butchered an old iphone charger cable. That got plugged into the mains. Tried again, better but still giving errors. Then I found what I think was the problem. The write speed was set to 100us. I played around with it and was able to achieve good reliability at 200us.
If anyone else has the same problems I'd change the write speed and add the external 5v (or buy a more expensive writer!!). Hopefully this information will avoid much banging heads against hard things!!
Just wanted to contribute to the knowledge base!! I've been looking for an EPROM programmer for a while. I've been using various sources (including Paul) for roms for a while, but got to the point where I felt that a programmer of my own was the way to go. I decided on a top853. They're £25 ish from eBay. Add on a uv EPROM eraser for £9 and away we go! Well, at least so I thought!!
My project was to "upgrade" my addams roms to addams gold. First off I needed an extra rom. I found one in a box of old kit. Ideal!!
Tried to burn one....error. Damn! Erased, tried again. Error!! Damn damn!!
A bit of googling revealed that the usb programmers frequently struggle with 27 series EPROMs as they program at 12v ish. The 5v, 500ma is stepped up but often isn't enough to write reliably. Google told me that if I were to crack the case open I'd find a non populated power plug to supply a juicier 5v supply. Out came the soldering iron and I butchered an old iphone charger cable. That got plugged into the mains. Tried again, better but still giving errors. Then I found what I think was the problem. The write speed was set to 100us. I played around with it and was able to achieve good reliability at 200us.
If anyone else has the same problems I'd change the write speed and add the external 5v (or buy a more expensive writer!!). Hopefully this information will avoid much banging heads against hard things!!
