Thank you...do you mean that?
82s126 82s129 82s131 adapter board and 82s123
- Thread starter patzik
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yes, that’s it.
Tailsnic Retroworks
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Hi. About speeds. If I use an unique 29F1610MC-10 rom for joining the 3 PROMs using 12 bits of the 16 bit total bus, the 100ns speed these memories use could be a problem? I want to use it on SEGA System 2 conversion boards, I think they don't use the 50ns speed standards
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Firstly thanks to @patzik for making and sharing the gerbers - the boards look great.
Has anybody had them manufactured yet and has one or two to share? If not I was thinking of getting some made but would only need 1 or 2 if others wanted some
Also - question for patzik - as you have PIN 1 (A15), PIN 2 (A12), PIN 26 (A13) and PIN 27 (A14) all connected to GND to tie them logically low, I'm thinking we could easily use a 2764, 27128 and 27256 instead of the 27512 as they are pin compatible and we aren't using any of the upper memory space?
Many thanks, Alex
Has anybody had them manufactured yet and has one or two to share? If not I was thinking of getting some made but would only need 1 or 2 if others wanted some
Also - question for patzik - as you have PIN 1 (A15), PIN 2 (A12), PIN 26 (A13) and PIN 27 (A14) all connected to GND to tie them logically low, I'm thinking we could easily use a 2764, 27128 and 27256 instead of the 27512 as they are pin compatible and we aren't using any of the upper memory space?
Many thanks, Alex
I also made my own 82S126/9 to 27512 adapter and posted the Gerbers here: Combined EPOS Aux pcb for PacMan board
I had quite a few pcbs manufactured since they were really cheap due to the small size:-
You are welcome to a couple if they are what you need. Fire me a PM.
The original 82S126/9 Proms and equivalents have fast access times. I believe using a 2764, 27128 etc., would be too slow. Newer EEPROMs (like the Winbond 27512) have fast access times, are cheap and still readily available, hence why these adapters are set up for these 27512’s.
Ah, almost perfect except that I need the board for a Galaxian PROM which is an 82S123 PROM whereas I think your boards are for a Pacman which uses an 82S126/9 PROM and from looking at the datasheets the outputs are different as the 126/9 has 4 outputs whereas the 123 has 8 outputs 
However it sounds like getting the boards made with DirtyPCBs or JLCPCB won't be particularly expensive - not sure who you used for yours?
On the speed of the EPROM used, one of the comments on this blog which did a prototype version too, says he used a NEC D2716D which I would have thought was too slow, but seemed to work OK for Galaxian
However it sounds like getting the boards made with DirtyPCBs or JLCPCB won't be particularly expensive - not sure who you used for yours?
On the speed of the EPROM used, one of the comments on this blog which did a prototype version too, says he used a NEC D2716D which I would have thought was too slow, but seemed to work OK for Galaxian
I’ve not made a separate 82S123 adapter (the only one I’ve done is integrated into the circuitry of a couple of PacMan daughter boards).
The fast access timing of these Proms is certainly overkill for these old arcade boards, so it doesn’t surprise me that a 2716 actually does work. The only real advantage of using an old eprom over an EEPROM that I can see is the size being slightly smaller. Also, if you have a stash of old Eproms then I can see why you might want to use them up instead.
I personally prefer using EEPROMs, mainly because you can erase and program them in seconds. Plus, it saves a rarer old Eprom which might be needed for a board repair instead.
I get my pcbs made with JLC pcb.
The fast access timing of these Proms is certainly overkill for these old arcade boards, so it doesn’t surprise me that a 2716 actually does work. The only real advantage of using an old eprom over an EEPROM that I can see is the size being slightly smaller. Also, if you have a stash of old Eproms then I can see why you might want to use them up instead.
I personally prefer using EEPROMs, mainly because you can erase and program them in seconds. Plus, it saves a rarer old Eprom which might be needed for a board repair instead.
I get my pcbs made with JLC pcb.
Size wise a smaller eprom will work, reason I did it for the 27512 was indeed the speed of the winbond eprom. Is this speed required, don’t know I guess it depends on how it’s used on the pcb. I am looking into making a new adapter that is smaller and works with the smd version of the 2764 eeprom but haven‘t had the time yet. I have some PCB’s for you but would have to ship them from the Netherlands, so having them made by jlc might be even cheaper.
Thanks and that's a very kind offer 👍
I've ordered both of your boards from JLC tonight as I had another board to get made so will report back when they arrive 👍
So my boards are in (thanks again @patzik ) and I've made two of them up to try and replace the PROMs on an Amstar Phoenix PCB
From the schematic for the Phoenix board it uses 2 x 74S287 PROMs or MMI6301 PROMs which I believe are equivalent to a SIGNETICS 82S129 PROM
So... my question is for the lower pad connection to configure the adapter as a 82S129 should I connect together pad 1 and pad 2 of the lower pad, or pad 2 and pad 3 of the lower pad?
As far as I can tell from the Datasheet for the Philips Components - Signetics 82S129, pin 13 is CE1 and pin 14 is CE2 so both of those are Chip Select so not quite sure which way to go with this one?
From the schematic for the Phoenix board it uses 2 x 74S287 PROMs or MMI6301 PROMs which I believe are equivalent to a SIGNETICS 82S129 PROM
So... my question is for the lower pad connection to configure the adapter as a 82S129 should I connect together pad 1 and pad 2 of the lower pad, or pad 2 and pad 3 of the lower pad?
As far as I can tell from the Datasheet for the Philips Components - Signetics 82S129, pin 13 is CE1 and pin 14 is CE2 so both of those are Chip Select so not quite sure which way to go with this one?
Maybe... looking at the schematic both of those pins, 13 and 14, are tied to GND and as they are active low, then this enables the chips at all times.
Still not sure with Patzik's design what the 27512 at the other end is expecting though, but as that is active low too, I'm guessing that wiring either of them would work if they are both grounded?
Still not sure with Patzik's design what the 27512 at the other end is expecting though, but as that is active low too, I'm guessing that wiring either of them would work if they are both grounded?