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Author Topic: Videopac + G7400 not working, some help need.  (Read 4911 times)
gertk
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« Reply #15 on: March 07, 2013, 07:43:35 PM »

Yes, I'am using Vellon vp-990
the 8748 is on the list.

Cool, you could even give it a personal 'twist'  Wink

http://videopac.nl/forum/index.php?topic=1730.0
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>>G7000 G7200(P+S) G7400 N60 JET27 VG5000 ZX80 ZX81 ORIC-1 COMX35 Aquarius<<
gertk
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« Reply #16 on: March 08, 2013, 08:21:20 AM »

I googled a bit for that programmer and it is not cheap: prices range from $500 to $800
Specs are impressive! Where did you get yours ?

I have a cheap USB programmer (TOP2004) and it broke down when a Commodore ROM was inserted for reading, some SMD transistor now literally lights up (and smokes) when I connect it to the USB port  Shocked
Oh, and the Commodore ROM died too...

I have programmed an Intel 8748 on my trusty ancient Digelec 824 programmer http://videopac.nl/forum/index.php?topic=1731.0 but a NEC D8748 refused to be programmed, the Eprom memory seems stuck at $C0 on every cell even after several erase cycles.
Another cause for this could be that the programming protocol is just different between the Intel and NEC
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>>G7000 G7200(P+S) G7400 N60 JET27 VG5000 ZX80 ZX81 ORIC-1 COMX35 Aquarius<<
Willy
Trying to get the cartridge in...
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« Reply #17 on: March 08, 2013, 05:55:12 PM »

I got mine at: http://www.ecuvonix.com/vp990-wellon-p-217.html

The standard mask roms are not eprom compatible !!
You need at least a home made adapter to read rom's.
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gertk
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« Reply #18 on: March 08, 2013, 09:53:07 PM »

I got mine at: http://www.ecuvonix.com/vp990-wellon-p-217.html

The standard mask roms are not eprom compatible !!
You need at least a home made adapter to read rom's.

Only the pinout of those roms was slightly different, I just expected the programmer to produce garbage or 0xFF when just reading the device, it should not have to use any of the programming voltages. Not even an adapter will prevent that. But with the TOP2004 even trying to read them is not safe. I also did not expect the programmer to get damaged by this, no current limits ??   Shocked
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>>G7000 G7200(P+S) G7400 N60 JET27 VG5000 ZX80 ZX81 ORIC-1 COMX35 Aquarius<<
Rene_G7400
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« Reply #19 on: March 10, 2013, 02:44:16 AM »

Only the pinout of those roms was slightly different, I just expected the programmer to produce garbage or 0xFF when just reading the device, it should not have to use any of the programming voltages. Not even an adapter will prevent that. But with the TOP2004 even trying to read them is not safe.

Apparently your programmer read the rom in verify mode, in which case the programming voltage is applied. That's why I always select an EEprom type when reading a rom.
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gertk
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« Reply #20 on: March 10, 2013, 11:16:02 AM »

Apparently your programmer read the rom in verify mode, in which case the programming voltage is applied. That's why I always select an EEprom type when reading a rom.

That is a great tip, I should have thought of that..
But luckily the rom images were available on the web so I could create a new (E)PROM with both the original and the updated version in a single chip. Some minor patchwork was necessary to make the pinout compatible and a thin cable which connects to a switch on the back of the computer to select.

By the way, did you get your 8748 already ?
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>>G7000 G7200(P+S) G7400 N60 JET27 VG5000 ZX80 ZX81 ORIC-1 COMX35 Aquarius<<
Rene_G7400
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« Reply #21 on: March 11, 2013, 09:19:22 AM »

By the way, did you get your 8748 already ?

I've got a 8748, but I haven't bought a programmer for it yet. (As I'm not going to use it much, I don't want to spend a lot of money on it.) To read the ROM of a 8048 I've built a circuit to connect it to my Eprom programmer.
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gertk
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« Reply #22 on: March 11, 2013, 10:30:26 AM »


I've got a 8748, but I haven't bought a programmer for it yet. (As I'm not going to use it much, I don't want to spend a lot of money on it.) To read the ROM of a 8048 I've built a circuit to connect it to my Eprom programmer.


If you ever need it programmed: I would be happy to 'burn' it in the Digelec  Smiley

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>>G7000 G7200(P+S) G7400 N60 JET27 VG5000 ZX80 ZX81 ORIC-1 COMX35 Aquarius<<
gertk
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« Reply #23 on: March 11, 2013, 10:32:32 AM »

Willy: did you get your 8748 already working?
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>>G7000 G7200(P+S) G7400 N60 JET27 VG5000 ZX80 ZX81 ORIC-1 COMX35 Aquarius<<
gertk
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« Reply #24 on: March 19, 2013, 12:32:54 PM »

BTW, I got the TOP2004 working again.. I replaced the burning SMD transistor by another similar PNP type and it works again.. Pfew...
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>>G7000 G7200(P+S) G7400 N60 JET27 VG5000 ZX80 ZX81 ORIC-1 COMX35 Aquarius<<
Willy
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« Reply #25 on: April 30, 2013, 07:42:18 PM »

Hi.
Small update.

At least after i've tryied 3 different pieces i got one org. intel working Smiley (from china NOS)

I've put new chip to machine and it is working Smiley
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