Madao wrote on 2021-11-05, 04:36:

You know why, i didn't puplished csv file: I'll never puplished their gerber file, sorry. I have make decision. It is a very profiable stuff with risk of misuse by commercial shop. I have talk with few people about puplishing of gerber file: All said: NO ! But i'll make and sell PCB with CSV file.

It's your design so I respect your right to keep it proprietary, but if a time comes where you can no longer be bothered to produce and sell PCBs I hope you will consider making the design files public then

Madao, thank you for your response. It sounds like the EDO should be 50, 45, 40, 35, 30, or 25 ns. And recent tests confirm 60 ns is OK.

My Mouser shipment arrived today. For those also putting in an order, be aware that the VGA ports don't appear to come with the stand-off screws. So if you don't have any, you'll want to source these as well.

maxtherabbit wrote on 2021-11-05, 17:50:

it shoult go without saying that it is ALWAYS ok to use DRAM with a *faster* access time than required for the application

I wondered about this. In general, to me it makes sense, but I wondered if it might be possible that the refresh interval may be sooner for faster DRAMs. The answer is a (probably) expected no - between for example the Mosel-Vitelic V53C818HK60 and V53C818HK25, the refresh period is still 8ms. It's not like the physics of the capacitors change. From what I can tell from data sheets, it doesn't seem like you can shoot yourself in a foot by using faster DRAM.

feipoa wrote on 2021-11-06, 04:07:

My Mouser shipment arrived today. For those also putting in an order, be aware that the VGA ports don't appear to come with the stand-off screws. So if you don't have any, you'll want to source these as well.

Ooops, yes, bolt/screw for mounting of pc bracket. I have forgotten adding him into csv-file. But i have a bag with new 1000 pieces from scrap.

But it should not a problem for you.

maxtherabbit wrote on 2021-11-05, 17:50:

it shoult go without saying that it is ALWAYS ok to use DRAM with a *faster* access time than required for the application

This is just mostly true. In the Excelgraph thread (a homebrew ET4000 ISA card), I dug up datasheets and found a violated timing constraint caused by RAMs being too fast. I can't tell you whether this is the reason of the issues the card had, but the creator of the card deemed the theory likely, that the memory outputting data too soon causing bus conflicts is the cause of the bad pixels that were observed.

mkarcher wrote on 2021-11-07, 11:36:

theory

maxtherabbit wrote on 2021-11-07, 12:59:

mkarcher wrote on 2021-11-07, 11:36:

theory

Quoting single words without context isn't necessarily helpful.

See this posts for an independent supporter of my theory: Re: EXCELGRAPH - ISA Video Display Controller (ET4000/W32i)

Back in the day there were motherboards that had issues with RAM that was rated higher than the bus speed.

Sometimes they would not like 100Mhz SDRAM running at 66MHz and trying to use 133Mhz SDRAM on the 66Mhz bus was even worse.

Well some Boards also only Support 168 Pin EDO Modules and often where mistaken as SD Compatible.

mkarcher wrote on 2021-11-07, 19:17:

maxtherabbit wrote on 2021-11-07, 12:59:

mkarcher wrote on 2021-11-07, 11:36:

theory

Quoting single words without context isn't necessarily helpful.

See this posts for an independent supporter of my theory: Re: EXCELGRAPH - ISA Video Display Controller (ET4000/W32i)

I'm not convinced that the visual corruption is caused by the DRAM being too fast. There are far too many other routing issues that could be plaguing his PCB design for me to latch on to yours without some kind of test to back it up. I.e. running the card with a slower speed grade without making other changes.

cyclone3d wrote on 2021-11-07, 22:39:

Back in the day there were motherboards that had issues with RAM that was rated higher than the bus speed.

Sometimes they would not like 100Mhz SDRAM running at 66MHz and trying to use 133Mhz SDRAM on the 66Mhz bus was even worse.

those are issues with SPD, not the memory ICs themselves

Stop with off topic, thanks.

Can I use a Winbond W27C512 eeprom for this? Do I need to duplicate the 32k bios file into a 64KB file for that to work with this size eeprom?

Yes it works, if you load ROM image to upper area (because highest address pin is on VCC , while this pin on 27C256 is VPP-input)
Duplicate of rom image works also well.

regards
matt

Madao wrote on 2021-11-08, 19:41:

Yes it works, if you load ROM image to upper area (because highest address pin is on VCC , while this pin on 27C256 is VPP-input […]
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Yes it works, if you load ROM image to upper area (because highest address pin is on VCC , while this pin on 27C256 is VPP-input)
Duplicate of rom image works also well.

regards
matt

Thanks!

All people, which got pcb...

Important: pleas don't forgot to soldering of JP6/7 (i have written it in CSV file.. but it is not good as solder instruction. )

Madao wrote on 2021-11-14, 17:59:

All people, which got pcb...

Important: pleas don't forgot to soldering of JP6/7 (i have written it in CSV file.. but it is not good as solder instruction. )

Thank you. I had been wondering about that. The sheet said "soldered", which is past tense. I guess it should read "solder pads closed".

Madao wrote on 2021-11-05, 16:18:

PCB ist now out of stock, sorry !

Noooooooooo!!!!

I just found this thread today 😥

Are you going to get more PCB:s?

I want to buy a couple

Sorry, no pcb left.

Well. If you change your mind and decide to make more PCB:s you will have customers