NB : Depending on which ebay shop you use, you may find some discrepancies in the advertised specifications!

Make sure you know what you're getting before you click <Buy>

Not all of the adverts on ebay make it clear what devices the TOP853 USB programmer is compatible with, there is often a list or hyperlink to a huge range of programmable ICs, such as the link above, but some adverts describe this programmer as supporting 5V devices, others say that it only works with 5V devices and others make no mention of the programming voltages supported at all.

I'm not sure how they can get away with, or example, saying that the programmer "Support 5V device only", then stating that it supports devices that require much higher voltages to program (but not to read) them. Other adverts state that the device can be powered from "USB or Power Cable", in fact, the same wording is printed on the back of the programmer - however, the TOP853 is USB only! There is no external power input, though there is a header on the PCB that you could connect to if required.

Write Problems? -

Programming Voltage & Write Speed (Delay)

When I bought the programmer, although I wanted to read some 2764 EPROMs, I did not give much thought to actually programming them. It was only after I had a few failed attempts writing a program to an EPROM that I gave any real thought to the programming voltage. Using the default setup in the TopWin program, selecting a NEC2764D EPROM and trying to write to the chip, the write phase would fail every time, at the same point, (address 0176h).

Older NMOS EPROMs, such as the NEC D2764, have relatively high programming voltages, for the D2764 it is ~21 VDC, newer, CMOS devices such as the 27C64 are compatible with an older 2764, but use a lower programming voltage, ~12.5 VDC.

Given that USB power is 5VDC, for the programmer to be able to program devices such as the 2764, the programmer would require an internal voltage "step-up" circuit, perhaps using a DC-DC switching regulator such as a TI LM27313+. Since USB 2.0 has a current limit per port of 500mA, the available power for operating the programmer and writing to the EPROM is pretty limited. I originally thought that it was likely to be a power problem, that the TOP853 could not generate the required voltage with enough current from the USB port. The TopWin PDF help file is pretty much unreadable, like may "English" manuals that accompany Chinese electronic goods, it's written in Chinglish! I did find a section in the Introduction that appeared to advise that the programmer could not program 27 series EPROMs though the USB port as it needed more than 500mA. I tried using one of these USB "Y" cables that are intended to provide additional power for external hard drives - which did not appear to help.

(+Update: I opened up my TOP853 and found that there is a 34063AP1 DC/DC Converter installed.)

My next thought was that since the device did look like it had started to write the program - getting as far as 0176h, I started to wonder if there was some sort of buffer overflow or write speed issue at work. I had not realised it, but under the Config Tab, there is a setting called "Delay", I take this to be the delay between the programmer writing to consecutive addresses, it was originally set as 100us. After doing some "tuning" of this parameter, I found that I could write to the 2764 with a Delay setting of 1ms. Again, if you can wade through the Chinglish manual, it seems to recommend a write speed of 2-20ms

Whilst it does work, I'm not sure that using a programmer with a potentially low programming voltage can be good for the long term reliability of the EPROM, if I were blowing EPROMs for critical applications, I would upgrade to a better quality programmer, but for hobbyist use, I plan on sticking with the TOP programmer at the moment.

Software - Windows 7 x64

So, now that I am reasonably with the capability of the TOP853, the biggest outstanding issue is that current versions of the TopWin6 software do not support 64 Bit Windows 7, so, I either have to run the Software in Windows XP Mode or on a XP laptop. However, I recently came across this information from hondaville.com which describes how to get the programmer to run under Windows 7.

<Quote>

Replace the files:

• wdreg.exe

• wdreg16.exe

• difaxapi.dll

They just seem to be using too old of files for it to work on windows 7.

I have read you need to slow down usb speed. From what i can tell it is on old versions of the top583. If you need to do this, you might have a setting in your computers BIOS to change the usb to 1.1, if this is not a option to you then you will need to run a USB v 1.1 HUB.

Files:

• http://www.hondaville.com/topwinwin7fix.zip

• http://www.hondaville.com/topwin6.exe