No BOM for that project yet. Fun! 😀

Personally, my goto is Mouser Electronics.

https://www.mouser.com/c/passive-components/? … 2F%20case=SIP-4

33Ohm I assume? Select that from the filters. I get 6 options from them. 😀

thanks for trying to help but they dont have this specific sip resistor ,needs to be network paralell topology isolated

scroeffie wrote on 2025-05-27, 22:22:

thanks for trying to help but they dont have this specific sip resistor ,needs to be network paralell topology isolated

In that case, what's wrong with https://www.mouser.de/ProductDetail/Bourns/46 … %2FyvTxXg%3D%3D ?

mkarcher wrote on 2025-05-27, 22:48:

scroeffie wrote on 2025-05-27, 22:22:

thanks for trying to help but they dont have this specific sip resistor ,needs to be network paralell topology isolated

In that case, what's wrong with https://www.mouser.de/ProductDetail/Bourns/46 … %2FyvTxXg%3D%3D ?

i think its the correct part but iam not shure because i never worked or used sip resistor so its all new to me

Oh, cool! Thanks for working on this and sharing it with the world.

Would it also be possible to add support monitors with 25kHz (or was it 24kHz?) horizontal scan, like the proprietary monitors for the Olivetti M24, AT&T 3600, etc?

The EGA Wonder 800 (without the plus) is apparently also built around a CHIPS P82C435, and supports this special mode by setting a jumper for it.

See https://www.techpowerup.com/gpu-specs/ega-wonder-800.c3180

(By the way, shame on techpowerup for excluding their site from the Internet Archive. This is historically relevant information.)

digger wrote on 2025-05-28, 12:52:

Oh, cool! Thanks for working on this and sharing it with the world. […]
Show full quote

Oh, cool! Thanks for working on this and sharing it with the world.

Would it also be possible to add support monitors with 25kHz (or was it 24kHz?) horizontal scan, like the proprietary monitors for the Olivetti M24, AT&T 3600, etc?

The EGA Wonder 800 (without the plus) is apparently also built around a CHIPS P82C435, and supports this special mode by setting a jumper for it.

See https://www.techpowerup.com/gpu-specs/ega-wonder-800.c3180

(By the way, shame on techpowerup for excluding their site from the Internet Archive. This is historically relevant information.)

just to be clear iam not the one who made this github 😀 iam just trying to make the card for my self .the person who made it did not incl a bom file
and i dont know how to contact him so ..

I happened to run into this bussed or isolated SIP resistor array problem on a different card that I assembled.

There were several different naming conventions for various types of resistor networks among vendors. Some vendors name isolated resistor arrays starting with B whereas bussed ones start with A, followed by 3-digit resistor values.

For isolated resistor arrays, if you really can't find the correct SIP resistor array model you can simply use individual resistors (33R in your case) by placing them in adjacent pins one by one (1-2, 3-4, 5-6, 7-8). Due to limited space, the resistors will need to be placed vertically.

LSS10999 wrote on 2025-05-28, 16:25:

I happened to run into this bussed or isolated SIP resistor array problem on a different card that I assembled.

There were several different naming conventions for various types of resistor networks among vendors. Some vendors name isolated resistor arrays starting with B whereas bussed ones start with A, followed by 3-digit resistor values.

For isolated resistor arrays, if you really can't find the correct SIP resistor array model you can simply use individual resistors (33R in your case) by placing them in adjacent pins one by one (1-2, 3-4, 5-6, 7-8). Due to limited space, the resistors will need to be placed vertically.

This sums it up nicely.

Bussed simply means there is a common pin among x number of resistors, where as isolated is just x number of independent resistors in a row, no common pin. I threw together an example below for the OP.

I've used independent resistors before in place of an isolated SIP before, works great. 😀

Also included an image of vertical mounted resistors since the OP said they were new to this.

thanks for helping 😀 those chip chips are not cheap
how do you cal what the value of the resistors need to be ? 33ohms/ 4=
8.3 ohms x4=33.2 ohms ?
i orderd the correct part thanks to link from mouser but i just wanted to know for maybe the future how to calculate this

scroeffie wrote on 2025-05-28, 18:35:

how do you cal what the value of the resistors need to be ? 33ohms/ 4=
8.3 ohms x4=33.2 ohms ?

You do not calculate anything. The SIP pack you are buying is just four 33 ohm resistors next to each other conveniently put into a single case. This means there are less components you need to place on the card, and it also likely saves spaces compared to four individual resistors.

mkarcher wrote on 2025-05-28, 18:44:

scroeffie wrote on 2025-05-28, 18:35:

how do you cal what the value of the resistors need to be ? 33ohms/ 4=
8.3 ohms x4=33.2 ohms ?

You do not calculate anything. The SIP pack you are buying is just four 33 ohm resistors next to each other conveniently put into a single case. This means there are less components you need to place on the card, and it also likely saves spaces compared to four individual resistors.

To help illustrate this...I just threw this together.

The photo below is the exact same as an isolated SIP array. The SIP array is simply smaller and more convenient. 4 resistors in a row, that's all it is. 😀

4 resistors in a row oke but they combine together 33ohms or is each resistor 33 ohms ?

scroeffie wrote on 2025-05-28, 22:05:

4 resistors in a row oke but they combine together 33ohms or is each resistor 33 ohms ?

Each resistor is 33 ohms.

possible to buy these nos ? would like to have all parts new https://www.ebay.nl/itm/277039973213

A quick ebay search turns up some that claim to be NOS or just "new".

https://www.ebay.com/itm/276111096612

https://www.ebay.com/sch/i.html?_nkw=P82C435& … ksid=m570.l1313

Quite a few sources for them used. If you have to get them used, that's not generally a problem. I buy far more used IC's than NOS and it's rare I ever have issues. Buy from reputable sources and do what you can to make sure your not buying "fake" chips. eBay buyer protections help a lot with that, as does buying from sites that specializes in what you're looking for. UTSource is a good one for obsolete parts.

i finished the project yesterday the card was working but bad graphics cut letters shaky video etc ,today i tried to reflash the eprom with another bios but i found out its not possible
with this atmel .now the card is not outputting any vid ,i think the dram 41464 is fake < ebay china ,i tried both lcd and crt

https://youtube.com/shorts/ANg6n_fNfmE

https://youtube.com/shorts/XKHwkAZpaJY

i think iam going to buy these just in case https://nl.aliexpress.com/item/10050057929743 … 7Cquery_from%3A