Acorn Electron love, 7x74 / 7x127 and RCBus3V3 progress, surgeries ...

[7alken]

Hi all, 

almost month ago I saw some Acorn Electron repair videos from Adrian Black and I almost immediatelly fell in love with this tiny machine with huge Ferranti ULA and almost nothing else on small PCB .... so I fot one "untested assumed faulty" fomr ebay for $43 GBP. 

This thing arrived okay, not working, but immediate idea was to reseat ULA (it is getting hot as hell and moving in and expanding the socket (its issue4 board) and it even screams for drop of MX4 under the metal cover and some adhesive heatsink on top .... after 20 minutes its not possible to hold fingers on it,  I dont measured it but expecing even 70deg or so ... crazy;

After cleaning of ULA socket and chip with IPA the machine was alive ... there was no PSU 19VAC, but I immediatelly bypassed/removed the internal PSU unit and connected only +5V form USB source, leaving -5V floating (later surprises, sure, I mixed the knowledge with Plus/4 where -5V is only for tape motor or so...) ... this way it was brought back into life (and I never knew anything about BBC Micro et al...). Keyboard with nice Futaba switches is woderfull (similar to AtariXL I had in 86-91, but possibly even better...) although 2 top rows had some dusty plastics inside them probably, mechanically resisiting especially with angled pushes, sure ... so I removed all the keycaps (soap water only then, no brightening yet, it looks okay) and started to bring IPA and mechanically torturing the keycaps internals quite heavily, and those 2 lines of keyboard are now almost perfect too... otherwise all needs to be desoldered, hard thing...  

One thing which is crazy on BBC Micro and especially on that Electron is that it has BREAK key (in fact switch just connected to CPU reset) at possition of todays BackSpace/Delete ... deathfull thing ... so, I am not retro purist and as this particula key is isolated on keyboard assembly PCB, not part of matrix, I isolated it hard way on traces and aliased this one with bodges to DELETE key which is cca 6cm below this one (of course, I swaped the keycaps too, excuse me Acorn ...). For BREAK/RESET I made tiny 5x5mm space in right part of bottom cover "grills" and put there microswitch with my loved machined pins sockets as 3pin "connector/receptacle" (these single line machined pins/sockets are really good as simple connectors, -I love them).

Then, having empty space of former PSU unit ... I started to think about battery/powerbank power for this thing ... having it powered for several hours from 10Ah xiaomi thing ... nice (Electron draw cca 0.75A at 5V, while poor ULA is probably half of this ...)... ya that powerbank dismounted fits there well, so I will put rocker switch in place of right barrel PCU connector and on left side is already USB-C dumb receptacle (for 2.4A 5V max from dump bricks, the smarter one needs some resistors on data ... the cheap xternal receptacle doesnt have them, but it was all easily mountable only using sharp reakable knife into center of bottom/top cover, only food alignment (of mounted case rather) is necessary ...

Sure, then I tried to use TAPE against sony digital dictaphone (and Audacity, sure), but there was drastic noise even on output ... now by schematic I realized the LM324 is really powered symetrically and needs that -5V too ... initially I only shorted -5V to GND, which helped with output (toally clean now, sure, nice) but input still not working ... sure; so I found ICL7660 polarity inverters here and abused one as deadbug with 10u and 47u on PCB power connector ... ok, solved, tape works perfectly .... but, that deadbug was brutally ugly, and then I started to think about even more deepre surgery in fact in relation to ather my projects related to 3V3 .. of course )) ...

PCB got that machined pins as new power connctor, this way 4 pins, as the pitch of original connector then almost fits those 4 with 2.54mm. Sure original PSU connectio uses some heavy/thick pins wchich can probably withstand 50A or so ... those machined pins are be okay up to 5A I am sure... 1A is nice (AtariXL has also spec of PSU at 1A, that big heavy transformer ...). Btw, as I really like the USB as single power source, even only 5V using some DCDCs on target, not plaing with USB-PD or QC anyhow ... also Sinclair QL and C Plus/4 (things I have here as only ziny selection of interestin machines) use negative voltages only for some quite weird and unimportant things, these days... later)

So, what about 7x74 ??? D-IP interposers ... I returned after that "mid may nukedc event" here, when I smartly accidentally cleaned my entire win C drive and I lost some things supposed to be synced by MS guys to onedrive, but this bloody thing stoped syncing me exactly at end of 2025 (probably 300k+ files, some weird filenames, no space issue ...). Well, so I tried cheap "DMDE" disk recovery tool (on magnetic drives it WILL be okay and do something good for you, on SSD with trim ... no way; I also dont reacted quickly, sure ...when this happens to you, ... pull plug from the mechine immediatelly and then start to think, and ask .... you may be more lucky than me ))

well,  back to 7x74 D-IP ... I have few made by JLCPCB here, gerbers are not lost, sure, my Kicad sources are lost, but nevermind, I will need also some more variants, and I now also know what are and how will these be done, I was using chatgpt history deeply to recover my "knowledge/projects timeline" of 2026+ ... (btw, 7xtgv working demo also lost, but Lyra keeps generated code in cloud, so I have this back too ... so far so good).

Those D-IP interposer can be in fact used in pair for "socketing DIPs", just instead of regular DIP sockets, possible to solder D-IP in place of DIP from TOP by flowing solder into holes, without any kind of wire/pin ... no problem... AND in case of precious PCB, where you want to replace soldered DIPs with sockets, its sometimes VERY HARD to remove them, at least dangerous ... so, one possibility is very deep surgery and extraction of the DIPs the "ugly way" ... this ussualy means throwing them away too, but in case of 7x74 D-IP interposers, you can save them and solder theirs ugly legs (after some tweaking/aligining/leveling after extractions) directly easily onto D-IP (you can hqve prepared batch of "hotplate" soldered 7x74 2x10pin 1.27mm connectors on them, where I settled after many hours of thinking on the scheme where motherboard has PINS and not female sockets ... these sockets are on chip/hybrids ... intentionally; ... its not because pins are fragile, they are not, on that 1.27mm dual line and LOW-profile, you have not almost chance to bend them ... no, but chips using sockets are simply still easier to handle ... of course hotplate soldering of them is one step more complicated, as you need to PARTIALLY(!) insert into socket also the SMD pins which serve ONLY as (disposable mostly) "heatpipe", this way process of soldering is EASY, repeatable, I figured out almost 100% reliability, its easy as far as Parkinson and that other german guy are not living nearby ....

So Acorn Electron is conducting quite deep/heavy experimental surgery now, while possibly will be tried also once to run at 3V3 (as that Ferranti -ULA, has this in spec too, even that Lyra thinks that obviously its not sure that custom internaly will work as expected ...). But, I also want to try to replace those 74LS  and 74S with modern parts allowing 3V3, either HC or LVC (aka toshiba VHC/LCX, I love them, cheap, nice datasheets, but not entire family, sure ... some older chips are not done using new tech)

Along with that Electron, I already mounted few 7x74 D-IPs  on already soldered RCBus lowprofile boards, where I was too fast and put there DIP sockets ...in fact to stay flat/lowprofile also in "interboard spacing", these sockets are WASTE, as D-IP soldered directly on the PCB (and even on hardly extracted chips/sockets, leaving residues in holes, no issue) having 2x10 1.27mm pins as 7x74 ""standard"" (in this case mapping pins 1:1 to DIP, sure - ther WILL be also narrow 24/28/32 plus fat/wide 24/28/32/40 at least ... again breakable interposers, using in this case the 2x20 pins/sockets - it is NOT possibel to combine huge amount of 2x10 to create 2x20 ... mechanically its unfortunatelly impossible, and making 1pin space is not clever ... so say 7x127 ""standard" for larger DIPs and even TSOP/BGA mostly memory SRAM/DRAM/SDRAM chips will use strictly  2x20 and 2x30 ... not expecing to torture this way 32bit chips in  tsop86/bga90 ... )

So Electron is on surgeons table, ya ... fingers Xed to bring it back into life (anyway, I expected it will arrive in far worse state, so I will try on him my new Siglent 4ch scope, older thing SDS1104X-E, not unlocked yet ... I dont like these touchy/slow andridized instruments ... ummm, okay). Btw, I was heavily considering good SI for 7xmem/7xmod both variants of connection (2x40 1.27mm and sodimm "DDR2/80+GND") and only recently I found also TangPrimer25K kit with SDRAM module, originated by MiSTer (I never thought about this as its mostly for gaming ... and it seems the guys were cheek to put there only single GND ... so Sipeed was forced to modify it with heavy pullups and CLK damping ... bt they go over dual 2.54mm connector up to 160MHz now probably too)... this Tang is really interesting modular thing also, I will design also something to integrate my/theirs SDRAM module for 7xmem, its good even for testing now ... plus also still is in game the fast and fastesr stm32 as an 7xsys CPLD simulation thing...

Ya, last months were concentrated mostly on "design for mesurement", how to do testpoints, what probing to use (just resitive using thin coax to 50ohm terminator is okay ...   btw BEST coax for ANYTHING seems to be RG178, VERY easy work with this one, it looks extremely thin, but usomg sat-cable stripped does perect job and then only scalpel to remove outer insulation ... PERFECT, really ... I made from it also composite video cable and even tpe interface ...)

pls, stay tuned :-)
P.

 

cool (actually HOT AS HELL) Ferranti ULA ...

sane BackSpace/DELETE ... excuse me, I never has this before ...

new RESET/BREAK microswitch (ctrl+break does hard reset, but even then basic program still stays in memory, use OLD command to restore it, ... sad thing is, it clears you memory in case you hit this break ... supposed backspace ...)

interestingly, MOS *KEY 10 allows you to persist ""autostart" key-sequence, which survives reset too ...

that cool thin RG178 coax, really perect work with this, if you never tried, lets try, I will not be doing anything shielded with different cable ... idea was to have coax thin anoug under 1.27mm for my 7xmem/7xmod tes-measurement "walls" (for best SI scanning, to have short gnd path, having all the signals with its own gnd for simple probe insertion - the probe is just cca 1k ohm resistor on live pin of coax, against scope 50ohm input, for my siglent, I needd to have there 50ohm terminated adaptors, sure) ...

tape in/out tested, good

this "octopus" is ICL7660 deadbug with some logs cut...

(will not change it, but it really needed better connector here ...)

before "deep surger", only cosmetic removal of these large/wigly 33n blockers,

even for dismounting DIPs, I wanted to take them out and put there mechanically smaller 100n blue MLCC-based ... in SMD world you even may simply use highr values as 1u or 2u or more ... as long as they are TINY ... that matters for blocking far more finally ...

testing of some mixtures of solder and flux, sadly I even dont know what that my best was originals made from ... but now I mix this with "jellybean rework" mosttly, that more flid thing is not good ... you need to have the mixture "sticky" as you are putting the PCB upside down with temporarily glued connector/heatpipes (or conn + temp heatpipes)
(as long as it heats up, its gone ... you MAY add some new, but generally, if you are carefull to center the thing well, its okay ... I have almost no errors now, and if they are, then ONLY "not soldering" and almost never "shorts", uven by spreading the mixture over all the solder pads and even over the gaps between them ... no issue, and I am using for mixing and even puting mixture that "ear clening tips" (halved and eventually cleaned by pliers shortening the dirty part by 5mm or so, several times) ... it turned to be ideal, better than syringe metal tip, so far so good ...baking these 7x74 / D-IP is childs play now ...

ya, no way to lay these 2x10pin sockets nearby .......

so, mandatory 2x20 and 2x30 (and 2x40 whis is full 7xmem/7xmod anyway)

(those smaller 20/30 for raw chips, to have them all socketable like 7x74,

I call this just 7x127 now ... and the goal is to have unified "logical pinout" even for all SRAM and SDRAM (or fpm/edo DRAM in some cases, like Electron ...) despite some in DIP or TSOP packages DONT have unified pinout and are not drop-in replacements ...
this "logical socketing" is supposed to overcome that also ... of course, different pinouts for SRAM and SDRAM, sure ... different layouts for horizontal mounting like those 7x74 we sed before ... and for VERTICAL mounting .. when you can save lot of space een on RCBus cards ... when designed for 7x74 / 7x127 pinouts ... and those chips/hybrids then can be (temporarily) inserted directly into "pinned sockets" using that ShenLIF concept ... when the PCB inserted is exactly 1mm thick - and may be even better HASL than ENIG ...)

RCBus card example with D-IP interposers instead of DIP sockets ..

(they dont look very nice here, but it is not affecting function, sure )))

Electron logic chips before surgery .... hard to desolder them, finally decided to be ugly and use "the tool" ...

short process ....

set of extracted 74s, some in not very good shape, but I will socket them on D-IP anyway ...

poor 74F saved from that XT board, I in fact thought I will never pull those, but now using 7x7x D-IP interposers... no problem to revive them this way as socketable things ....

sincerelly,

Petr

[7alken]

and here also some links, my yt playlist of "all things Electron" mostly ... plus as I am still fascinated by all near "gate arrays", even oldest one ... something too plus nice japanese page about theirs chip technologies history, here related mostly near 1980 (I was searching about possibility to use early Si CMOS also on 3V3 while not specified, sure, thing is, they can be made just similar to HCT these days, with that TTL logic, question is how about power for them ... here I can only pray for Hitachi HD6350 ACIA ... sure ...

https://www.youtube.com/playlist?list=PLNTovoOR6LBg

https://en.wikipedia.org/wiki/Gate_array

https://www.shmj.or.jp/english/integredcircuits/ic80s.html?utm_source=chatgpt.com

https://en.wikipedia.org/wiki/Astec
(I knew only TV modulators from them, they was actually company who fabricated initially the Electron, and issues caused it missed that christmass ... ya, hard)

https://dn760004.eu.archive.org/0/items/Electron_User_Vol._1_No._1_1983-10_Database_Publications_GB/Electron_User_Vol._1_No._1_1983-10_Database_Publications_GB_text.pdf

 https://github.com/moogway82/JamSoftElectronULA

https://en.wikipedia.org/wiki/COMAL

https://www.4corn.co.uk/archive/docs/Acorn%20Information%20-%20Volume%201-opt.pdf

https://en.wikipedia.org/wiki/Sideways_address_space

https://beebwiki.mdfs.net/index.php/Paged_ROM

https://beebwiki.mdfs.net/Sideways_RAM

https://web.archive.org/web/20160306153913/http://www.acornelectron.co.uk/hardware/cats/acp_pres.html

https://www.acornelectron.co.uk/ugs/electron/acorn_computers/ug-english/contents_eng.html
(really good manual, that BBC basic has some surprises in syntax, expressions instead of poke/peek and many others ... but, so far so good,

as I thought also about prototyping vmex/aslix using "some kind of basic" to be close enough to retro world ... this is in fact possible, having it transpiled form QL LSB say (as single source of truth, or some pseudocode - which IS finally also purpose of "aslix", sure) ... possible ... 

some web emulators ....
https://elkjs.azurewebsites.net/

https://0xc0de6502.github.io/electroniq/
this is probably best ... but as always, mapping of keyboard is complicated, "elkulator" has some keyboard mapping, I dont have it installed yet, though ...

(actually, I was so cheeky to swap also Z and Y on my Elecron keyboard, crucial to stay alive, and it IS somehow possible to remap keyboard even without modifying ROM, probably ... I was only quickly peeking into this ...and sure BBC Basic has embedded 6502 assembler, too, ya)

generally, I am glad I read somethong about BBC Micro machines, theirs basic, theirs hw concepts, interesting ...

(fact is the original ARM has nothing common with later things Arm7tdmi+ ... the somehow "oppinionted" basic has there origins too)

P.

[7alken]

and .. to not put blame on Astec (common), issues were just with that quite complex ULA at 16MHz mode 0 pixelclocks etc ... in first batches;
and when i heard why, it shined totally different light on my 3V3 experiment ... even more challenging ... so few notes from unwanted source and some book:

https://dokumen.pub/qdownload/electronic-dreams-how-1980s-britain-learned-to-love-the-computer-9781472936653-9781472918338.html

... anyway, both Electron and RCBus3V3 are now testbeds for 7x74 and 7x127 for socketing even larger 3V3 DRAM ...

(interesting it that Electron issue 6 had option to put there SIL22 module of four PLCC 4164 ... we had here now also 4464, sure,

so for memory chips, I wanted these precisiono sockets for precise alignment of some mezanine board, the same for CPU and ROM,

where was then later made some "slogger turbo driver", freeing CPU from ULA interventions in entire space, so lower 8kB incl crucial register file in zero page was shadowed in dedicated SRAM - here can be made also lots of new experiments, I feel)

btw Electron has simple digital RGB output, probably easy to process with fast MCU for TFT display in realtime;

and for composite video signal quality, in fact that MONO output selected by jumpers is really better, but on that LK4 jumper is in fact color signal where both together do just superior S-Video ... (maybe  best thing to mount in place of TV modulator, these days ... but that case and keyboard are generally precious for many kinds of abuses, anyway)

P.

[7alken]

well, initially afraid a lot of desoldering the larger CPU and ROM, but these are inserted without any weird legs bending, so, VERY carefully using regular silicone tip sucker (and I did also tiny protrusion for soldering tip in silicone, to have it possible better, it seems it is) AND then using hotair from top while VERY slow pulling them out from bottom using thin knife ... hope the temp was not deadly ... hopes and fears, sure ... but anyway some CPUs are here; it will be okay; sure for these I want to put precision machined sockets, sure ... the same as for DRAMs (which HAVE bent legs though ...interesting, I never saw that SIL22 modules, but found theirs picture too ... there is also update Electron service manual with notes about board issues differences and far better schematic scan (having bugs like 74574 instead 74S74 too, sure ...)

silicone tip protrusion visible here too ... I had this initially too long, better to stay short to not wiggle, sure; 

this was put in schematic and PCB as option for issue 6 of Electron (that one with "blob" "Aberdeen" ULA)

P.

[7alken]

hi all, update, from the process ... I finally decided to carefully clean those extraced 74 logic footprints to place machined sockets there (idea to possibly combine this for some mezanine with socketed CPU/ROM, or just to play with CPLD logic boards there ... problem MAY BE final height, using 7x74 D-IP interposers in them, sure ... not final; but for intermediate test, I will just today make those ugly extraced 74 on D-IP, after heavy fight also with soldered ROM ... most ugly while desoldering are all places without thermal reliefs, all those GND pins on "copper pours", this is almost impossible to heatup ... ya; worse places, definitelly ... so it was long and lots of work; nevermind; blocking caps aren't blue but yellow, but definitelly mechanically smaller and not obtrusing anything, okay ... that was tiny thing ... I experienced one DIP trace lift finally, but hopefully corrected; following photos show some D-IP soldered directly on uncleaned footprints after extraction (well, leveled, resoldered, then pushed and soldered through)... btw, those D-IP will be better to have tight THT holes just for round machined pins and slightly larger spacing form SMD footprint, maybe rectangular pads instead of circles/annulars ... especially that SMD pin headers footprint is wider than female one (for chips/hybirds), unnecessary complication ... sure, tweaks imminent ... and I want to release only really "battle tested" results... (if somebody wants the gerbers now, no problem to send ver. "A" too) entire family will be wider/complete ... its just on drawing  table, together with DIP32+16 "top-mounted" line of SMD pullups for +16 pins, also designed to be easy, and of course, such tiny modules can be finally factory made with some new technology TSSOP variants on panels; that was the idea several steps forward ... but end goals here are really any CPLDs as best (programmable) option (love for epm3064 tqfp/plcc) ... once all is tiny, orders form JLCPCB are cheaper; 

So, isolated DIPs replaced by D-IPs and inserted chips (this "direct" way is NOT higher than using DIP socket, esp when horizontal TSOP 7x74 used) .. here in Accorn at south side of PCB, I am not sure now if the sockets added will not cause "too high" assembly under keyboard ... but thing is now solution of D-IPs with machined pins to be "sitting" directly on soocket, at least (beware of leaking tin down to some holes/socket) ... some long machined pins exists, will see... (interesting is they are quite diverse, some 0.4, 0.5, 0.6 diameter ... and when once inside machined socket is inserted the thick pin, then its "permanent", later inserting of thin is unreliable ... so, be carful here, this all needs to be hardly sed in specs ... )
(fact is soldering sockets back required in case of that GND pins mostly to cut the legs and solder from top, as it was almost impossible to clean the ONLY those holes... ya)

around 74LS169 I will add the both LK jumpers which allows to use also 74xx163 instead ... clever from Acorn, this one is far more common (even new tech) still ...

meanwhile, as I disovered also TangPrimer25K kit with extremelly tiny B2B fpga module and primarily theirs XSDS V13 modified SDRAM module, it arrived and (un)surprisingly, that V13 schematic had almost anything pulled up hardly, at least prepared on PCB but the finaly produced result HAS NOT them all ... calculated draw was possible few hundreds of mA of waste ... okay; generally I was surprised by this XSDS and even MiSTer thing, never saw this before ... but for them it must be somehow working, so I hope it will be okay here too all around 7xmem/7xmod/7xsys later;

huge fight ... this rom GND was tough;

some sockets, some "direct" D-IPs ... some kapton tape for bottom of D-IP insulation, also on the chip/hybrid (bottom has pinout for THT)
CPU+ROM back in precision sockets (made from few DIP32, np)

some D-IPs with soldered original extracted 74s inserted, something to do ....

that TangPrimer25K and sdram module XSDS V1.3 (but unpopulated by all pullups in fact)
this FPGA module is mounted by TINY B2B thing to base interface board, crazy (smaller than that canadian dollar and the queen)
... in front are Digilent PMODs, okay, we can follow/extend PMOD by reusing also our low-profile 2x10pin 1.27mm too (7xbus is intentionall on 2mm 2x15pin)

that all for now,

P.

[7alken]

hi all, well, first reassembly of Electron usinf my 7x74 D-IPs looked bad ... not beep after power on, but it was almost expected, I in fact forgot to clean up all the solderd things deeply in IPA and sometmes in raw ethanol (I gave that to osc 74S04 finally, then IPA...), and I was afraid mostly around that XOSC circuit, as I modified the situation by lifting the chip 5mm above PCB, so affecting the sensitive oscillator thing ... ya; ... measurement of power on chips okay, but NO CLOCK, .. so no fun, sure ... on original (in fact quite heavily damaged 74S04) was nothing ... so I first pulled everything from mobo, even CPU+ROM and all of the 7x74 things, chips and adaptrs were wasing in IPA, twice in fresh ... and I also cleaned with IPA and then with ethanol also that sticky bottom of PCB where heavy soldering happened mostly, ... not entire board, no soap water total bath, in fact I am mostly concerned always by connectors, those DIP sockets etc ... and even super tiny 1.27mm 2x10pin females ... this needs to be protected from dust and anything, sure ... so, yesterday was wasing time, nigtly drying ...

I also realized that my SN74S04 is probably really DEAD, using T48 flasher/tester (has not only that LS169, but has 163, sure), but probably, ony today after wasing of everything and on CPU and ROM used also "contactol" the tester showed the truth, yes I killed that 74S04 ... other chips are alive, while looking not nice, sometimes ... in fact, also I had other LS74 thrown away before too, ehre one XT donor board had them (plus few 74F and other 74S, while not much for me now, they are quite precious, so that board used as weirdd organs donor is okay ...) ... but I dont have here SINGLE 7404 ... so, I tried to peek, yet another old board I have here is also XT, where I found goldStar GD74S04 which literally saved my ass in this endeavor .. this was tested as OK (I used windows install of T48 latest software, into virtualbos on CachyOS Linux, it was necessary only to simplify USB filter, just VID/PID and name, otherwise it wasnt found there), and so I reassembled the thing (expecting also some possible issues with my "direct D-IP" soldering on Electron board, or anything, although I experienced only one small trace lift, which was locally solved ... 

So, reassembling and powering up ... BEEP, with composite video output ALL OK ... good, only those DIP sockets make entire beast "too high" in bottom part of motherboard, but I feel that when I put there TSSOP filled 7x74 (hct probably and later even others 3V3 try), those tiny quickly made on hotplate .... it will be okay, so not extracting the sockets (AGAIN) yet ... btw, I put machined sockets there to maintain possibility to insert there some thin SMD board, only as remotelly possible option ... some things like "sloggger turbo drive" and some CPLD experiments or so ... not crucial in this Electron ... it was abused as "testbed" and 7x74 D-IP "soldering process tuning" system ... 

sp. I need to make pause here to solve other things also, mostly updating proper inventory of parts, as some new things arrived and for RCBus3V3 and my other projects I am accumulating some goodies... this was necessary, and it is not complete, but good to have such testing system and ... it is not running on batteries, yet :-)

entire album of photos from the process, comments mostly in filenames
https://photos.app.goo.gl/eA2yegxbmfxeJwPeA

sincerelly,
P.

this guy saved my butt ... tnx ))

[Dennis Burke]

I'm intrigued by a 3.3V RCBus, it solves some issues regarding real-estate. Keep posting updates.

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[7alken]

ya, thanks, this is broder set of things ... I will post separate thread related, as it needs reviews from experts and RCBus specs discussion too;
P.

[7alken]

meanwhile, here I only tested all my Rockwell R65C02 from ebay as working in Electron, not sure about power consumption, good thing to have integrated in "testbed";
and for ROM, for now, modified PLCC32 to DIP32 socket using ONLY 0.5mm machined pins; I have here both 5V0 and 3V3 verisions of 512kx8 flashes, not ready wide D-IP, yet;
(the removal of ugly squared pins required heavy brutal destruction pin by pin and cleaning holes, but its doable, sure)