Genius G840 (or G540) programmer -- first experience and GAL programming issue - Page 1
Forum section: electronics / general

author: ebastler
author_rank: Super Contributor
timestamp: June 21, 2015, 12:12:34 pm
content: My homebrew EPROM and GAL programmers are both from the early 90s, require a parallel port on the PC, and refuse to support any more recent chips. So I figured it's time to buy a new programmer. But given the fact that I wil use it rarely, I wanted to keep costs down. I opted for a Chinese Genius G840 USB programmer; $80 shipped from ebay.So far, it has lived up to my expectations. After a couple of hours playing with it, I can share some first tips, and have one big question:I opted for the G840 model, which has an external power supply. (There is a G540, which supposedly is identical except for the fact that it is USB-powered only. I also want to program ancient EPROMs with 25V programming voltage, and the G540 is known not to have sufficient power for this.) Learning #1: While the ads and the manual claim that you can power the G840 via USB, as long as you do not need the extra power -- do not bother trying! The USB +5v line is unconnected inside the G840, so you always need the external power supply.Learning #2: When installing the software, do not chose a folder inside the "program files" folder. The software wants to write settings infomation to its main folder, and produces all kinds of quirky error messages when it can't. Stick with the default path, or some other folder with write access. The software will still have an awkward GUI with Chinglish text, but will essentially work.Now for the big question:Has anyone managed to program GALs with this thing (either the G540 or the G840)?While I am waiting for a few new Atmel ATF GALs to arrive, I have tried various Lattice and Nat Semi 16V8s from my box of leftovers. The Lattice 16V8s could be erased, but not written at all (all fuses remain at $FF); the Nat Semis were programmed, but with 10% to 20% of false fuses. Same results on half a dozen each of these chips, so I think it's not the particular chips, although they are old and some are used.I have managed to program EPROMs with my G840, so it's not a total fraud. I can't imagine that something as common as a 16V8 can't be programmed with it (although, given the blatant false advertising regarding the power supply options, I am not so sure...) Maybe the original 16V8 type is so old that they have indeed never tried them, and I will have more luck with the more recent types? Or my unit has a fault?Any reports of success or failure are much appreciated!

author: BloodyCactus
author_rank: Frequent Contributor
timestamp: June 21, 2015, 11:50:01 pm
content: I use my g840 often, (arcade eeproms, amiga roms). I'm pretty sure I did some PAL + GAL chips (old ones from ebay, may or may not have been NOS or used). I run my under winxp inside virtualbox on linux, works fine. I did some i2c microchip 24LC256 eeproms yesterday.

author: ebastler
author_rank: Super Contributor
timestamp: June 22, 2015, 04:15:41 pm
content: Thanks for the reassurance, BloodyCactus.I can now add another encouraging data point: My brand new ATF16V8B GALs have arrived, and the G840 can program them nicely. So it seems that either all my old 16V8s are damaged -- can't rule that out, although it would be an unlikely coincidence. Or the original 16V8 (not 16V8A or any of those newfangled versions) is so old that the Genius engineers never tried it on the programmer, and overlooked some subtile differences in the programming algorithm.Anyway, not a huge concern, since I can always use one of the newer types if I ever find the need to replace or reprogram a 16V8 in an old circuit. So I'll keep my G840 and behappycontent with it...

author: LeisureSuitLarry
author_rank: Newbie
timestamp: August 19, 2015, 07:50:56 pm
content: Don't waste zour time any further with GAL16V8 (not A, B, ... types) and these programmers. The software uses the same sequence for RA60 fuses as for the later versions with charaters. Another issue is that programming voltage is not high enough.I developed a solution for bothssues i, which I may publish here in case some folks are interested. It requires an addition resistor of 10 kOhm and some excellent eyes for soldering ...

author: Paul_from_Brum
author_rank: Newbie
timestamp: July 06, 2016, 03:15:25 pm
content: Hi I would be very interested in your 10K modification as I am trying to program some ATF22LV10's with a G540 programmer. There seems to be a distinct absence of any programming hardware specifications on the net.Many thanks

author: LeisureSuitLarry
author_rank: Newbie
timestamp: December 14, 2020, 02:12:43 pm
content: Sorry, I couldn't focus on this topic over the recent years, so I'm sharing the pictures of the modification for completeness.