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TOP853 Eprom programming 27128 roms

Posted: Sat May 30, 2015 7:48 pm
by thedark
i have troubles of programming eproms.
somehow it fails every time whet it is on 0005F (FF)
then it stops ...

this whas a working DFS rom reserved for Super MMC to burn in for the compact.
but after one week trying 20 eproms i have a black out.
can anyone help or know how to, i could not find any info on this matter.

Thanks for heling in advance..

tonny

Re: TOP853 Eprom programming 27128 roms

Posted: Sat May 30, 2015 8:10 pm
by poink
http://primrosebank.net/computers/maint ... top853.htm seems to suggest reducing the write delay. Also, it sounds you might find 27C128 chips work better, as they use a lower programming voltage.

Re: TOP853 Eprom programming 27128 roms

Posted: Sat May 30, 2015 10:18 pm
by 1024MAK
poink wrote:http://primrosebank.net/computers/maint ... top853.htm seems to suggest reducing the write delay. Also, it sounds you might find 27C128 chips work better, as they use a lower programming voltage.
I think you mean increasing the write delay...

All USB powered EPROM programmers suffer from being unable to supply enough power to program 21V and 25V EPROMs properly. In addition, not many properly support the 5.5V or 6V supply voltage recommended for some of the later EPROMs that can be fast programmed.

So as said above, use the 12.5V EPROMs. And keep backup copies of the data used to program your EPROMs, as they may not hold data for as long as you would expect when they have been programmed with a USB programmer.

Mark

Re: TOP853 Eprom programming 27128 roms

Posted: Sat May 30, 2015 11:08 pm
by thedark
Wil an external psu help instead of an usbport
i have 1 21v 6x cmos and the rest is 12.5v
but i think that i better of with the otommer for bbc b

Re: TOP853 Eprom programming 27128 roms

Posted: Sun May 31, 2015 3:19 am
by 1024MAK
If your EPROM programmer has an external power input, yes, use this.
I have a Willem programmer and this is able to correctly program 21V EPROMS when I use a 12V external PSU.

You may still have to change the timing as described in the link in the post above.

Oh, and always do a blank check first. When erased, every memory location in an EPROM should be &FF. The programmer can only change bits from ones to zeros. Erasing the EPROM is the only way to change each bit from zero back to a one.

If you have a EPROM programmer for the Beeb, yes, try programming your 21V EPROMs on it.

Note: I do not recommend Willem programmers like the one I have (or similar versions) for most people because there are a lot of jumper/link settings and it is easy to make a mistake.

Mark

Re: TOP853 Eprom programming 27128 roms

Posted: Sun May 31, 2015 7:51 am
by thedark
On the main board is a solder on point for it.
if i use this do i have to disconnect the power on usb.
or do i put the 5v straight on the board.
i have parts to do this.
but i am not sure if its possible.

Edit: Added a picture of the inside.
right is a place for external power.

Re: TOP853 Eprom programming 27128 roms

Posted: Sun May 31, 2015 10:46 am
by 1024MAK
Without knowing how they have "wired" up the circuit, it is just guesswork. So I don't know.

Just because there is provision on the PCB for a socket does not mean just adding a socket will help. The next question is: "What voltage and polarity would this socket accept?"

As I cannot find a schematic of the TOP853 programmer on the web, the only way to find out, is to reverse engineer it (map out the tracks, connection and components and draw a schematic up from scratch).

But before even thinking about that, first have you tried it on all of your computers USB ports? Some may be able to deliver more power than others.

Do you have an externally powered USB hub? If yes, use this with just the TOP853 (and the computer) connected and try again.

Also try programming the same EPROM with the same data multiple times to see if the programmer can get any further each time you try to program it.

Here are some links to people having the same or similar problems:
http://forums.arcade-museum.com/showthread.php?t=192978
http://www.vintage-computer.com/vcforum/
http://www.lemon64.com/forum/
http://www.eevblog.com/forum/
A site search unsurprisingly brings up lots of hits for TOP853 on www.eevblog.com/forum...

Good luck :mrgreen:

Mark

Re: TOP853 Eprom programming 27128 roms

Posted: Tue Jun 02, 2015 7:51 pm
by thedark
got it to work...

question.

i have the compact who can hold two roms in an 27c256 eprom
but how do i put two roms in there.

whet i burn one rom in there its working good. but how do i burn the seccond in there?

any toughts out there?

Re: TOP853 Eprom programming 27128 roms

Posted: Tue Jun 02, 2015 9:08 pm
by bprosman
What did you do to get it to work ?

Usually when loading a file in the eprom programmer software you can give an offset. That should be $4000 for half a 27256

Re: TOP853 Eprom programming 27128 roms

Posted: Tue Jun 02, 2015 9:31 pm
by thedark
installed a laptop with win XP
using 12.5v Eproms and reduced the write speed 2ms or 1ms
and set in the bios the USB2.0 to USB1.1 so it slow down.