Please add to this discussion if you get One ROM working in your retro system(s)!

[piersfinlayson]

I'd love to hear what systems people have successfully used One ROM in.

So far, I have successfully used it in:

• C64 (PAL)
• VIC-20 (PAL)
• 1541
• PET 4032

I'm hoping to get some more (non Commodore!) retro systems soon to test One ROM in.

I've also been told that One ROM works in:

• TI-99
• CoCo2

[piersfinlayson]

Atari 800XL BASIC ROM successfully replaced using One ROM Ice USB. No software changes required.

[DanBrownleeOps]

Pointing out that is also worked fine for Atari 800XL OSROM 28 pin/27C128.
https://www.atariage.com/800/emulation/

[LouisBurdett]

The Atari 800XL was my first computer. I don't think I love enough to get one but I love it enough that seeing one revived makes me smile :)

[banman11]

I have found one ROM RP2360 using Character ROM image to be working on a C128D.

[piersfinlayson]

Nice!

[1st-elektron]

I replace a P6 Rom with OneRom of the Apple II FDC. It works like a charme.
Latest version of OneRom with 2716 configuration and P6 contents.
Regards Michael

[1st-elektron]

I successfully implemented an Apple ROM 9316A in OneRom

file 9316A.json:
{
"version": 1,
"name": "9316A",
"description": "A simple Apple II+ ROM 9316A config with 1 ROMs",
"rom_sets": [
{
"type": "single",
"description": "2KB EPROM with fixed CS2 active_low - 2048 bytes, 24-pin package",
"roms": [

            {
                "description": "2KB EPROM with fixed CS2 active_low - 2048 bytes, 24-pin package",
			    "file": "D:/HAM/bastelprojekte/one_rom/Apple_D000.rom",
                "type": "2316",
				"cs1": "active_low",
				"cs2": "active_high",
				"cs3": "active_low"
            }
        ]
    }
]

}

[banman11]

Very nice!

[banman11]

One ROM STM32 Ice running c128 Character ROM on C128

https://youtu.be/ptFwXXAanF8?si=MTcfaYhUZuYDRYtk

[electricwool]

using onerom web custom image/rom upload. Fire 28A3, 27256, latest firmware. This works on the Passap e6000 computer using the latest roms from 1995.

[piersfinlayson]

Ah, the knitting machine :-)

[electricwool]

I am very much looking forward to nvram emulation because it opens new possibilities for programming patterns. at present the only option for programming patterns is a rather irritating process of tricking it into thinking that it is talking to a floppy drive every 100 rows or so to read a new track that is quite convoluted where you need to stop, read the track from a pc via a program that emulates the connection, load that pattern using the clunky interface then recalibrate and resume knitting and it is very easy to make a mistake during this process. This is a problem across the silver reed, brother and passap machines. then there are the $500 cables and $500 software licenses and you need one for each type of machine. if I could simply load a new section of memory over usb for each pattern program then it could be reduced to a single trigger. Some of the old embroidery machines also suffer from this problem with the lack of precious working memory cards. the husqvarna viking machines were $20k machines that just get recycled for their steel for lack of roms.

my favorite part is the "quotation marks"

[banman11]

That's a great way to use the One ROM device!
Definitely need to get NVRAM up and running. So many uses.

[1st-elektron]

i have made a case for the model stm32f4-24-pin-rev-h.


onerom-top-text1.stl.wav
onerom-bottom.stl.wav
delete ".wav" from stl files

Have fun
Michael

[lowrybt1]

Has anyone used One ROM to replace the 2316 character generator ROM used by Ohio Scientific Instrument (OSI) Challenger computers?

[piersfinlayson]

I haven't heard of anyone doing it. I don't se any reason why it wouldn't work if it's the usual 2316 pinout.

[piersfinlayson]

From youtube comments:

just got the 28 pin one rom, and tried it in my 24pin Kaypro 10 (using the modification that jumpers vcc and connecting pin2 to pin2 of the cpu)and it works perfect,

[piersfinlayson]

Atari 520STFM with Rainbow TOS 1.04. This is on a machine that takes 2x1Mb (231024) ROMs. I haven’t tested but expect it would also work as 6x256Kbit (27256 style) ROMs.

[piersfinlayson]

I found that the front One ROM fouled the metal shielding (which the keyboard seats on), so desoldered the socket and soldered One ROM directly onto the board. Obviously, One ROM can be reprogrammed via USB in situ:

[piersfinlayson]

A certain somewhat well known youtuber has One ROM emulating a 27256 in an IBM PC XT:

[teeeby]

Hello,

When ROM sockets are very close, almost touching, the One ROM is slightly too wide to fit in adjacent sockets. I have a photo of an obscure PC clone with four ROM sockets showing this but my browser is old and I can't attach it.

[electricwool]

if it is so closely spaced then you could slightly modify the board by trimming 2mm off each side and choosing castellated holes or stagger the one roms by using rows of pins with different heights. 3mm, 7mm, 3mm, 7mm.

[piersfinlayson]

One ROM typically uses the space on the outside of the pins for routing power traces around the board, so triming the board down is not easy. This might force a move to 4 layer to shrink further, although I have been wondering about a castellated design.

OTOH, when the board is vscored, you can probably reduce the width by 0.5-0.75mm total by running a craft/stanley/exacto knife along the sticky outy bit. The key is just to avoid any traces.

@teeeby I'd love a photo with One ROM for scale if you can figure out how to share. Or via email - I'm easy to find

[piersfinlayson]

It sounds like the OP (on discord) did manage to workaround the size problem, but I'd love to make a narrower version.

[teeeby]

I'm replying by email and I've attached the image. If you don't receive it, I could invite you to the Discord server where it was uploaded earlier today. P.S. I'm just an observer.

…

On Wed, 4 Mar 2026 at 18:33, Piers Finlayson ***@***.***> wrote: One ROM typically uses the space on the outside of the pins for routing power traces around the board, so triming the board down is not easy. This might force a move to 4 layer to shrink further, although I have been wondering about a castellated design. OTOH, when the board is vscored, you can probably reduce the width by 0.5-0.75mm total by running a craft/stanley/exacto knife along the sticky outy bit. The key is just to avoid any traces. @teeeby <https://github.com/teeeby> I'd love a photo with One ROM for scale if you can figure out how to share. Or via email - I'm easy to find — Reply to this email directly, view it on GitHub <#31 (reply in thread)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AXYACIWCVZJCJBVOMWFCAMD4PBZHZAVCNFSM6AAAAACH5Q2AEOVHI2DSMVQWIX3LMV43URDJONRXK43TNFXW4Q3PNVWWK3TUHMYTMMBQGEYTCNY> . You are receiving this because you were mentioned.Message ID: ***@***.***>

[piersfinlayson]

No, sadly, it didn't come through. Feel free to invite me to the server - I'm piers.rocks on discord.

[teeeby]

Discord invite: https://discord.gg/SMkYU9rh Image URL: https://cdn.discordapp.com/attachments/1445786822247583804/1478625071496036362/IMG_4335.jpg?ex=69a91468&is=69a7c2e8&hm=1fde99bbd5cdcd3cb0893e4b0f2de336591c60e677072dd353598b091ab9bd69&

…

On Wed, 4 Mar 2026 at 19:34, Piers Finlayson ***@***.***> wrote: No, sadly, it didn't come through. Feel free to invite me to the server - I'm piers.rocks on discord. — Reply to this email directly, view it on GitHub <#31 (reply in thread)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AXYACISOJY4AZSCURRHYEET4PCAKTAVCNFSM6AAAAACH5Q2AEOVHI2DSMVQWIX3LMV43URDJONRXK43TNFXW4Q3PNVWWK3TUHMYTMMBQGE3DKNY> . You are receiving this because you were mentioned.Message ID: ***@***.***>

[gnievin]

I don't have an immediate need for one, but I can see Signetics 2513 compatibility being useful. This character generator ROM was used in old systems like the Apple 1 and early Apple ][:

https://www.applefritter.com/files/signetics2513.pdf

https://retrocomputing.stackexchange.com/questions/13419/what-is-the-format-of-the-apple-1-character-set-rom
https://www.thealmightyguru.com/Wiki/index.php?title=Signetics_2513

I made an adapter like this one to use a 2716 in place of a 2513 lowercase ROM (which I didn't have) in an ADM-3A terminal:
https://www.esocop.org/docs/LearSeieglerLowerCaseOption.pdf

[piersfinlayson]

Yes, I’ve shied away from doing this one because a) it really does need a custom PCB and b) there are adapters (like yours) that can convert from a stock 2716 (or One ROM!) to 2513. If someone wants to take one of the stock One ROM designs and design a PCB to replace a 2513 I’m more than happy to add firmware and tooling support.

[Pontiac76]

486dx2-80, PC Chips M912 v1.4, XTIDE v4

https://theretroweb.com/motherboards/s/pcchips-m912-v1.4-486
BIOS Files: 40-P301-001437-00101111-072594-DGREEN and UMC-498GP-2C4X6B13-00
ROM Model: 27C512

XT-IDE Universal BIOS

https://www.xtideuniversalbios.org/binaries/
BIOS Files: r638/ide_386l.bin
ROM Model: 28C256

[arcaicandy]

Adding support for HM7641s allowed my to add all the images for the WIlliams Video Decoders (1-6) into a single OneRom, set a jumper to select VD2 and then replace the original in my Defender. Seems to work perfectly.

[piersfinlayson]

Loving this - so much technology to replace a 1975 512 byte PROM!

[scoates]

MeshCoCo

Tandy Color Computer (3, but should also work with 1 and 2)

I have a weird project that is powered by One ROM; thought I'd share it here. I have plans to do another similar project and I'll probably write them up more formally, but other than a few posts on Mastodon (and showing people locally), I haven't really published anything about this yet.

I have a One ROM serving as the cartridge/pak ROM in a Tandy Color Computer 3.

That, alone, is barely remarkable. It's just a "standard" AT28C64 that I pulled out of the Diagnostics cart sold by RetroRewind (within which, the board is this freely-available one). I desoldered the stock ROM and replaced it with One ROM, successfully.

The part that is remarkable (at least I think it is), is that I managed to harness the One ROM plugin system, wrote a plugin in Embedded Swift (yes, that Swift), and interfaced my old 1986 CoCo 3 to a Heltec V4 radio, over serial. So, now I have my CoCo on the local MeshCore network.

Edit: the CoCo side's app is served from the One ROM as if it's a regular ROM, and it speaks to the plugin which converts to TTL serial and talks to the HeltecV4. The CoCo itself speaks the MeshCore serial protocol to the plugin.

There are some quirks (like writing to a ROM, and browning out the power rails with the radio), but over-all it's working now, and it's really fun.

[piersfinlayson]

Are you powering it through the 5V header pin?

That's interesting. I wonder if you can put a larger capacitor in somewhere to help?

It does sound like a brown-out situation although I wonder why it doesn't come back - but the RP2350 doesn't seem awesome at booting again if it fails to boot for a power reason. I might be missing something.

I'll probably get around to test this a bit myself when I get a new version of Airfrog produced (ESP32 based), which again will have a large power draw. Right now the AP2112K Voltage regulator has a 4.7uF cap on the 5V side of it. More might be betterer, but a large cap local to the radio board might also smooth it out. Something big like a 47uF.

[scoates]

Yeah, CoCo -> ROM Port -> One ROM -> One ROM's 5V + GND pins -> Heltec V4's 5V + GND pins.

I did some really rough math and I think I'd have to put in a REALLY big capacitor to cover the whole LoRa (radio) burst at "high" power. Though if I'm right on the edge, and the coco provides most of the power, that calculation was probably flawed. I haven't actually tried this yet, but it's a good idea.

[electricwool]

ESP32S3 has BLE and WIFI. if both the radios are on this can draw more than 300mA plus 250mA for LoRa. it's easy to exceed the limit of a 500mA usb port with this. I am going to assume that the brownouts are solely caused by the OneROM USB resistors being configured as a 500mA port? so the power supply probably cuts power as a part of the USB spec.

[scoates]

It works fine on USB only. This is a CoCo bus power problem, if it's brownouts, which I believe it is at this point. 🤷‍♂️

[electricwool]

I see now. It has a 300mA fuse which is even less current. I assume this fuse protects the transformer windings. and is placed before the input to the transformer so you get transformer losses and regulator losses after this. 300mA fuse >>> 100/220V >>> [transformer loss]>>>15VAC >>>[rectification diode loss]>>> ~12V rectified >>> 5V regulator >>>[ half power lost as heat] assuming at least 10V makes it to the regulator >>> ~100mA power budget for the 5V rail.

so the limit is likely voltage sag on the transformer output. On my old computerized knitting machines I am just ripping out the old transformers and wiring in a 3D printed plate with a barrel jack for 12V. you get the added benefit of a modern power brick with modern safety features instead of 50 year old cooked mains wiring inside the box. for the coco2 you could easily use a 9V PSU or a USB-C panel jack/bulkhead connector for the supply. I notice that the CoCo2 has a negative-5V rail. you could supply this with a LM2662 module. then just -i dont know the trace thickness- add an extra wire to support the existing 5v traces for the power supply to the cart.

A larger cap will smooth transient spikes but voltage sag will remain a problem. a 5V CPU will probably crash if undervolted before the voltage sag on the 5V rail reaches the cutout voltage of the OneROM 3.3v regulator. From memory the RP2350 has a default EFUSE set protection voltage of 2.7V because it can be expected to reliably boot above this threshold but the CoCo's MC6809E is likely to not work at this voltage.

[banman11]

I would hazard a guess that the browning out is power supply related. I personally don't have a coco3 (I have a several coco2's ) these coco2's power supplies are pushing it to the limit.

https://www.google.com/search?q=Tell+me+more+about+the+coco3++power+supply&client=ms-android-samsung-gj-rev1&hs=KHCB&sca_esv=1e797e5baba2f096&sxsrf=APpeQnuFsu-eQJuHY_G9iZlLI0pdzMLXmw%3A1787947051381&ei=K-iRapnxFvulhvcPzK7smQk&biw=411&bih=757&oq=Tell+me+more+about+the+coco3++power+supply&gs_lp=EhNtb2JpbGUtZ3dzLXdpei1zZXJwIipUZWxsIG1lIG1vcmUgYWJvdXQgdGhlIGNvY28zICBwb3dlciBzdXBwbHlIppEBUNdaWJmHAXABeAKQAQCYAdMDoAHACaoBCTAuMS4xLjEuMbgBDMgBAPgBAZgCBKACtQTCAgQQABhHwgIKEAAYRxjWBBiwA8ICBBAeGArCAgoQIRgKGKABGMMEmAMAiAYBkAYIkgcFMi4wLjKgB-gMsgcDMi0yuAfdA8IHBTMtMS4zyAdpgAgB&sclient=mobile-gws-wiz-serp

[banman11]

[strongkm]

The 40 pin is a great project for the Amiga 500. I have diagrom 2.0 and kickstart 3.1 and 2.04 working fine on my Amiga 500 6a.

Hope to try some others in my BBC and c64 soon.

Well done Piers and thanks for your work :)

[piersfinlayson]

Awesome!

[LouisBurdett]

Amiga 600 with Fire 40B loaded with three kickstarts and a DiagROM.

• I'll use external DIL dip or momentary switches, to select the ROM I need.
• I don't recommend installing the header pins, they will prevent the case from closing. Rather than removing mine, I bent them flat.
• I'll try to find a way to keep a short USB cable accessible externally. I might not have space in the expansion bay with the memory board and CF reader there, so I'll place a socket behind the PCMCIA slot along side the switches.

[piersfinlayson]

Cool! Did you need to overclock One ROM to get it working with the A600?

[LouisBurdett]

No...

• I didn't know the One ROM could be overclocked. Gonna have to read the docs.
• Also, I've not extensively tested yet. I've loaded a game, WB 3.2.3, and WHDLoad.
• Do you know what symptom I might see if overclocking is required?

[piersfinlayson]

You'd just fail to boot if you needed to overclock. It's interesting because someone else reported their A600 needed One ROM overclocking. I wonder if there's motherboard jumpers indicating the speed of the ROM and yours set to "slow" and the other person's were set to "fast". I don't know for sure the A600 has such jumpers, but other models do.

[LouisBurdett]

I'm not aware of such jumpers (but there's loads I'm unaware of). My board is a rev 1.5. Do you know what rev board the other A600 was? I've heard the 1.5 has better accelerator compatibility than the 1.3, so may be related?

[piersfinlayson]

I may have been misremembering the A1200: #248

[danielboston38]

Has anyone gotten One Rom working on the rc2014? if not i am planning on adding this. also have some other ideas that would potentially make this a even more cool device.

[MartinR-UK]

Short answer is, yes! Slightly longer answer is, yes and it works brilliantly!

I have a OneROM 32 installed in my SC126 Z180 SBC, and it works just great!

The OneROM has enough space to accommodate three 512kByte ROM images for the SC126. I use the first for the latest dev version of Wayne Warthen's RomWBW, the second for Steve Cousin's SCM, and the third I use for my own experimental code. It's really convenient to be able to remotely reset the SC126 from the same desktop PC that I use to write code and build the ROM images.

I remember posting some pictures to this thread, but don't seem to be able to find them now... so, here's one.

I think that OneROM is a great product - and wish I'd had it back in the early 1980s when I was writing Z80 code for real rather than for fun.

Keep up the good work, Piers!

[rekordc]

Kind of, I running it in my z80bus system. First the 28pin as 128kb rom now the 32pin as 512kb rom. Greetz Martin Op vr 11 sep 2026, 02:43 schreef danielboston38 ***@***.***>:

…

Has anyone gotten One Rom working on the rc2014? if not i am planning on adding this. also have some other ideas that would potentially make this a even more cool device. — Reply to this email directly, view it on GitHub <#31?email_source=notifications&email_token=CEXBDNHYFGFEXOH7P2P4AYT5ONDCNA5CNFSNUABIM5UWIORPF5TWS5BNNB2WEL2ENFZWG5LTONUW63SDN5WW2ZLOOQXTCOBTHEZTIMZYUZZGKYLTN5XKOY3PNVWWK3TUUVSXMZLOOSWGM33PORSXEX3DNRUWG2Y#discussioncomment-18393438>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/CEXBDNANFCSUPJBFN3UE2L35ONDCNAVCNFSNUABHKJSXA33TNF2G64TZHM4TONRSGU4TKMJTHNCGS43DOVZXG2LPNY5TQOJWG4YTSNVBOYBA> . Triage notifications, keep track of coding agent tasks and review pull requests on the go with GitHub Mobile for iOS <https://github.com/notifications/mobile/ios/CEXBDNGNDTQCZXQLNEPQU2D5ONDCNA5CNFSNUABIM5UWIORPF5TWS5BNNB2WEL2ENFZWG5LTONUW63SDN5WW2ZLOOQXTCOBTHEZTIMZYUZZGKYLTN5XKOY3PNVWWK3TUUVSXMZLOOSVGM33PORSXEX3JN5ZQ> and Android <https://github.com/notifications/mobile/android/CEXBDNAYKZE2HHIXX3O62AT5ONDCNA5CNFSNUABIM5UWIORPF5TWS5BNNB2WEL2ENFZWG5LTONUW63SDN5WW2ZLOOQXTCOBTHEZTIMZYUZZGKYLTN5XKOY3PNVWWK3TUUVSXMZLOOSXGM33PORSXEX3BNZSHE33JMQ>. Download it today! You are receiving this because you commented.Message ID: ***@***.***>

[Gun-neR]

Using a Fire24 OneROM, I installed a switchable custom character font for my Commodore PET (Chosen on power-up, based on momentary button press - See the pic with the blue white wires... No more lifting the lid for the jumper. The other red button is Reset)

NOTE, I didn't make the font, it came from here.

But I did have to fight with AI to make a script that properly pulled only the letters and numbers out of it and integrate them into the standard Character ROM file (in my case the characters-2.901447-10.bin found at zimmers.net

That script is here: PET-font-swap.py

And for my ultimate test, I successfully ran BACK2PET demo with the custom ROM and no glitches in the use of PETSCII for the graphics... I think the font really adds to the look :)

2nd NOTE, the other OneROM pictured was my first ever use of these wonderful things... A friend had burned and supplied the EPROMs and adapters to upgrade my PET 2001-N-32 to BASIC 4.0. But I had given him an incorrect file for one of them... And as it was going to take too long for him to burn me a correct one and get it to me, I used my 1st ever OneROM to fill the gap. One day, when I order some more from PCBWAY, I will replace all of those EPROMs with a total of two Fire24's programmed (once I figure out how) and wired for Simultaneous Multi-ROM mode. (Too bad they can't support 5 simultaneous ROMs ;P )

[piersfinlayson]

Very nice. Ah, PETSCII robots - I wondered where I recognised the font from.

[sdsnatcher73]

I used the OneROM in a Panasonic FS-A1 MSX2. This machine has a 128kB mask ROM which I emulated through TC53100 with active low CS. I gave the machine Kanji BASIC and now want to try to give it also JIS1 ROM. Looking for any documentation that allows the single OneROM to emulate a second 128kB ROM in the same machine (it did not have this machine but the logic to address it is present in the MSX engine it uses).

[piersfinlayson]

Very cool. I think I saw one of these (or at least a very similar machine) at VCF over the weekend.

You are looking to emulate 2 x TCS531000s from a single One ROM?

See here for how to do it: https://github.com/piersfinlayson/one-rom/blob/main/onerom-config/test/28-multi-231024.json

This is supported in 28C and 28D, as it needs the X1 pin.

You'll need to run the CS line from the second 2312024 into X1.

[solidpr0]

Successfully used OneROM to replace a faulty EPROM in at Nintendo Famicom/NES cartridge. This would work for any game but in my case the cartridge was a boot cartridge for a Hotel Famicom Box - a special 15-game Nintendo Famicom used in hotels in Japan in the 1980s.

Most Nintendo games carts have a Program ROM and a Character (gfx) ROM and so the OneROM was a simple way to replace these with a modern solution. I've covered this in more detail on my blog.

[scoates]

The real ROM is marked "LH231097". I am using --slot file=./ikari-prg.bin,type=23C1000,cs1=active_low (and I did try overclocking with ,cpu-freq=200MHz).

[piersfinlayson]

I might go a little further on overclocking just to rule that out - maybe up to 275MHz. turbo-boot might be worth trying as well, as well as powering the NES on while One ROM is already powered booted (using USB, with USB plugin). I expect you've already tried this but just in case ...

I doubt it's the speed though - that's a relatively slow system so should be well within One ROM's capabilities.

[electricwool]

NROM (Mapper 0) with the Japanese 'Top Loader' Famicom. depending on the version of retron I am going to guess that the retron machine actually bitbangs the ROM into RAM on boot and so isn't affected by timing and might have different filter/RC circuitry. Timing is unlikely to be the issue because the famicom CPU reads at speeds slower than 500ns. so you'd need at least 400ns of jitter which is unlikely. does it boot if you use the reset button instead of power cycling? if the console power supply has a long rise time the CPU could boot before OneROM. ive found a lot of so-called 5V CMOS silicon runs perfectly well at >3V. so if it takes a few microseconds to charge the capacitor on the 5V rail OneROM might just not boot fast enough. it should be possible to modify the CLI to log and diagnose this. OneROM also uses the rp2350A4 so the hardware can double as a powerful 400mhz logic analyzer. plug a second one in and compare the reading on the data pins to the mask rom.

The github for your board also says that it might need 100ohm resistors installed for the extension cable.

[scoates]

So, first, I apologize for the noise in here. At this point, I have determined that it is my flaky remoted-via-IDC-socket ribbon cable setup.

Hopefully I can make it up to you all with a little bit of data:

• I had tried powering the One ROM with USB hoping to have it booted before the NES needed it, and that didn't change anything.
• This is probably irrelevant, but just so all info is out there: the NES I'm using is modded with Hi Def NES (which is awesome, by the way), so there are both CPU and PPU interposers that COULD change things here, but I doubt it. Still not a 0% chance.
• On both the fake NES (Retron) and the real NES, the One ROM responds to ROMSEL in about 40ns. Voltages are in the same ranges, or at least close enough that it should work. Both the mask ROM and One ROM look pretty much the same on the scope.
• So, while I barely have this working (it regularly crashes, but I'm certain that's caused by my bad harness), One ROM is indeed working as a ROM on this NES UNROM cart.
• This is with a normal clock; not overclocked.

One ROM responding on D0 (2) to ROMSEL (1):

And the whole flaky setup:

Sorry again for the misinformation before. I should have been MORE suspect of my bad harness; it was just giving me too many [false] positives on the fake NES, which I now believe was a coincidence or at least a consequence of moving it from my desk to the living room and back..

I'm going to redo those IDC socket connections (with a better IDC crimping tool), and if that's still a mess, I'll hand-solder the 56 connections. 🤞

If any of you happen to be coming to VCF Montreal (2026 2.0) next month, I'll hopefully have this stuff there at the Foulab table.

[electricwool]

Did the 100 ohm resistors help on the UNROM? I think they are something to do with impedance matching for the cable. https://github.com/MouseBiteLabs/NES-Cartridges/blob/main/Discrete%20Logic%20Mappers/README.md#sprite-glitch-resistors

[solidpr0]

Yeah I don’t know all that much about NES carts but I did see, and notice that think about horizontal and vertical settings on the cart. I’ve seen where you jumper it but don’t know how this correlates to what is written to the ROM - although it would be easy for me to test if I knew what I was doing as I now have a socketed cartridge with a big hole chopped in the side!On 22 Sep 2026, at 07:47, electricwool ***@***.***> wrote: also possible to bridge both the H and V pads and configure in ONErom for H or V? —Reply to this email directly, view it on GitHub, or unsubscribe.Triage notifications, keep track of coding agent tasks and review pull requests on the go with GitHub Mobile for iOS and Android. Download it today! You are receiving this because you commented.Message ID: ***@***.***>

[electricwool]

a simple low tech hack would be to also install a DPDT switch for when you load vertical or horizontal mirrored roms. maybe add it as a feature request? could you upload a picture of the traces so that it's easier to see what is connected to the solder bridges? maybe add a feature request? something like configurable in the ONErom type selection as famicomV or famicomH

[solidpr0]

What's a DPDT switch. I just read up a bit on the horizontal or vertical scrolling 'jumper' on the cartridge. The article I read suggests it 'helps' - what happens if you run a game with vertical scrolling and the mirroring is set to horizonal?!

I think in the real world you would probably just keep two sets of carts with one for horizontal and one for vertical, no?

[electricwool]

DPDT = douple pole double throw. It's a switch that connects two wires in one position and two different wires in the other position. it would allow you to flick a switch to switch between the solder bridge for V and H being connected. you could have two different carts but this would make it easier to toggle it with a switch. all that would happen if you had it in the wrong position when loading a cart is that it would have glitchy graphics. vertical scrolling is for games like the fighter pilot sims that scroll top to bottom as you fly over an area like Crisis Force. Horizontal scrolling is for side scrollers like mario.

[electricwool]

Sockets? we don't need no stinking sockets.

able to extract knitting patterns from a LH53512 with OneROM Lab. The rom turned out to be a nothingburger that only stored patterns. ancient CMOS rated at 3µs@5V
read at 6µs@3.3V for integrity/stability.
on the upside there were undocumented incomplete patterns and a coherent reference table. As it is all patterns, the most it can store is a 61kb pattern which has the potential for a larger memory with emulation than any existing stock knitting machine. they usually go up to 32kb for custom patterns.

[thecaver99]

Can I ask what is the difference between the 40 rgb usb and the 40-l rgb usb, i know the 40 pin has been tested in the amiga 500 but would 2 work in the 1200?

…

On Tue, 6 Oct 2026, 10:39 electricwool, ***@***.***> wrote: Did the 100 ohm resistors help on the UNROM? I think they are something to do with impedance matching for the cable. https://github.com/MouseBiteLabs/NES-Cartridges/blob/main/Discrete%20Logic%20Mappers/README.md#sprite-glitch-resistors — Reply to this email directly, view it on GitHub <#31?email_source=notifications&email_token=AFN56WN4CWVLEVUL7H27UCD5SS4URA5CNFSNUABIM5UWIORPF5TWS5BNNB2WEL2ENFZWG5LTONUW63SDN5WW2ZLOOQXTCOBXG42DGNRUUZZGKYLTN5XKOY3PNVWWK3TUUVSXMZLOOSWGM33PORSXEX3DNRUWG2Y#discussioncomment-18774364>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AFN56WJBYTYALQ5SA4EAPXD5SS4URAVCNFSNUABHKJSXA33TNF2G64TZHM4TONRSGU4TKMJTHNCGS43DOVZXG2LPNY5TQOJWG4YTSNVBOYBA> . Triage notifications, keep track of coding agent tasks and review pull requests on the go with GitHub Mobile for iOS <https://github.com/notifications/mobile/ios/AFN56WKH4IVUKTQPVHDEEUL5SS4URA5CNFSNUABIM5UWIORPF5TWS5BNNB2WEL2ENFZWG5LTONUW63SDN5WW2ZLOOQXTCOBXG42DGNRUUZZGKYLTN5XKOY3PNVWWK3TUUVSXMZLOOSVGM33PORSXEX3JN5ZQ> and Android <https://github.com/notifications/mobile/android/AFN56WI3MWC6Y7PSDPDIRHT5SS4URA5CNFSNUABIM5UWIORPF5TWS5BNNB2WEL2ENFZWG5LTONUW63SDN5WW2ZLOOQXTCOBXG42DGNRUUZZGKYLTN5XKOY3PNVWWK3TUUVSXMZLOOSXGM33PORSXEX3BNZSHE33JMQ>. Download it today! You are receiving this because you commented.Message ID: ***@***.***>

[piersfinlayson]

The 40-L RGB has 4MB of on-board flash rather than 2MB. It means the 40-L can hold up to 7 x 512KB ROMs or 15 x 256KB ROMs.

The 40 RGB supports up to 3 x 512KB ROMs or 7 x 256KB ROMs.

Otherwise they are identical - the 40-L is just a flash size increase.

Yes, One ROM works in the A1200, although you need to increase One ROM's clock speed, and space between the 2 One ROMs is an issue. The space issue is surmountable with a couple of different techniques.

See #248