Crazy idea? Downgrade Electron to an Atom? Possible?

discussion of games, software, hardware & emulators relating to the Acorn Atom
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mister35mm
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Crazy idea? Downgrade Electron to an Atom? Possible?

Post by mister35mm » Fri Mar 02, 2018 6:36 pm

I used to have an Acorn Electron (Love-hate relationship)

Instead of paying heaps for one on ebay or building one from scratch, I wonder if it would be possible to replace the ROM in an Acorn Electron (Cheap and plentiful) with a kind of super-Atom so that the Super Atom could use the Electron's ULA?

I know it's a little crazy...

The other possibility is a created Atom on an Electron sized PCB. I mention this I now own a few electrons with dead ULAs but all the other parts are 'ok'.

No flames please!

regards


ThomasHarte
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Re: Crazy idea? Downgrade Electron to an Atom? Possible?

Post by ThomasHarte » Fri Mar 02, 2018 7:52 pm

You'd need to reproduce the Atom support hardware — the 6547, the 6522 et al — in a physical format compatible with the Electron ULA, I think. The original chips wouldn't work because the 4-bit RAM is a cost saving that requires work to pretend to be an 8-bit bus.

On the plus side, the RAM has more than enough bandwidth as it can sustain 2Mhz of 8-bit access, and I understand the Atom is normally clocked at 1Mhz. You wouldn't get video snow unless you added it on purpose.

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Multiwizard
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Re: Crazy idea? Downgrade Electron to an Atom? Possible?

Post by Multiwizard » Fri Mar 02, 2018 8:58 pm

Hi,

I´m the one which has from time from time nice ideas :idea: but,,

don´t tell or ask me something technical, I know and understand nothing... 8)

I´m the dumbest member of *. I´m just very enthusiastic (about Acorns(especially the Atom))... \:D/


Greetings, Wim... :-)

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Re: Crazy idea? Downgrade Electron to an Atom? Possible?

Post by paulb » Fri Mar 02, 2018 9:48 pm

mister35mm wrote:The other possibility is a created Atom on an Electron sized PCB. I mention this I now own a few electrons with dead ULAs but all the other parts are 'ok'.
You'd be better off helping to get modern ULA replacements into service and reviving those Electrons. (Some background here.)

As for the Atom, those peripheral ICs are just not present in the Electron, although I was wondering only very recently why Acorn didn't put a 6522 in the Plus 1. Maybe the main aim of the Plus 1 was just to add the cartridge ports that the Electron should have had as standard, even if that meant not having a machine the same size as a tissue box.

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Re: Crazy idea? Downgrade Electron to an Atom? Possible?

Post by crj » Sat Mar 03, 2018 1:20 am

The ethos of the Electron was to leave out absolutely everything that could be left out. Which is why cartridge slots were relegated to the Plus 1.

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Re: Crazy idea? Downgrade Electron to an Atom? Possible?

Post by ThomasHarte » Sat Mar 03, 2018 4:37 am

I feel like the interrupt-driven tape interface is quite a bit more complicated than what you could get away with, I'm sure people could have coped without the motor relay, and if they were really trying to leave as much out as possible then why not drop the composite and RGB outputs and just run those signals to the expansion connector? Put those ports, like the analogue port, on the Plus One to save on the connectors.

But if you really want to save money, with hindsight, maybe actually remove quite a bit less than they did, and just get to market on time?

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Re: Crazy idea? Downgrade Electron to an Atom? Possible?

Post by paulb » Sat Mar 03, 2018 12:37 pm

crj wrote:The ethos of the Electron was to leave out absolutely everything that could be left out.
Yes, I think most people realise this. But as Thomas notes, if you're targeting the home market, things like the RGB connector and composite connector are largely superfluous: only later would it become more convenient to use these to connect the machine to televisions via SCART and, later still, via the front-panel accessory ports that perhaps became more common when home video cameras started to see wider adoption.
crj wrote:Which is why cartridge slots were relegated to the Plus 1.
So we discussed this before, and my assertion is that it was a mistake to rule out having at least one cartridge slot in the base machine. Home users might have tolerated loading software from tape, but schools and other organisations probably got tired of that pretty quickly (remembering it happening only once or so in my distant past). You could always add a disk system, but that was expensive even for the Beeb with all its ports. Meanwhile, cartridges could have offered the convenience of rapid or instant loading, would have commanded a premium over tape software, and would have been more difficult to "duplicate" by institutions not wanting to pay up for software.

Now you're going to say that the Electron wasn't aimed at education. Well, that's another case of Acorn wanting people in certain markets to spend their money on the more expensive stuff, as opposed to letting those people decide whether they wanted more computers or fewer, fancier ones. Some schools would have been happier to double the number of computers they had without considering getting stuff like the Spectrum. (Of course, Acorn was fortunate that the rush to acquire microcomputers happened before Amstrad got into the market properly.)

Another thing is that the Commodore machines also had cartridge slots. But I guess Acorn figured out their inherent utility eventually for the Master 128, being Acorn's last chance to re-spin the 8-bit stuff, throw in everything but the kitchen sink, and - for all we know - run down their stocks of cartridge-related parts.

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Re: Crazy idea? Downgrade Electron to an Atom? Possible?

Post by oss003 » Sat Mar 03, 2018 2:00 pm

I think it's not possible to convert the Electron into an Atom because there are to many hardware differences.
And you still need the ULA for the display.

The best way to get your Electrons working again is getting a new ULA or replace the ULA with an FPGA: http://www.stardot.org.uk/forums/viewto ... f=3&t=9223

If you don't want to do this, you can always replace the internal board with a RPi running an Electron/BBC or Atom emulator.

Greetings
Kees

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Re: Crazy idea? Downgrade Electron to an Atom? Possible?

Post by crj » Sat Mar 03, 2018 3:29 pm

paulb wrote:if you're targeting the home market, things like the RGB connector and composite connector are largely superfluous: only later would it become more convenient to use these to connect the machine to televisions via SCART and, later still, via the front-panel accessory ports that perhaps became more common when home video cameras started to see wider adoption.
The Electron was launched a year and a half after the BBC Micro. That's a long time in a fast-moving world. Already, a lot more televisions had unmodulated inputs thanks to VCRs as well as home computers.

But a bigger issue is that, once you have one video output, providing alternatives in the main unit is cheap, and providing them via an expansion port is relatively tricky. Looking at the circuit diagram, once you have the UHF output, adding RGB just needs the socket, a 3-pin header, a quarter of a 74-series quad XOR gate and three resistors. I mean you could feed RGBS to the edge connector and put those components in an expansion, but really?
So we discussed this before, and my assertion is that it was a mistake to rule out having at least one cartridge slot in the base machine.
Conversely, there were a dozen or so ICs involved in all the address decoding and latching within the Plus 1. But more than that, there was a lot of mechanical engineering involved. As well as the added expense, there was the added development and tooling time. Remember the Electron was being released to a tight schedule as well as a tight budget. Indeed, even without including a cartridge slot, the Electron was late and that ruined Acorn.
Now you're going to say that the Electron wasn't aimed at education. Well, that's another case of Acorn wanting people in certain markets to spend their money on the more expensive stuff, as opposed to letting those people decide whether they wanted more computers or fewer, fancier ones.
More, a case of the BBC Micro having been designed with a very strong focus on the education market, and being much better attuned to their needs. If they'd wanted Electrons to go into schools they should have added not a cartridge slot, not a disc interface, but Econet. But they never did: schools kept buying Beebs, so there was no real point.

Remember, also, that in an educational environment the cost of the plastic box full of electronics is only a small proportion of the overall cost of a computer. You also need staff to support them, somewhere to put them, etc. Given the far lower usefulness, the superficial cost saving made no sense. (Indeed, the Electron never made as much sense as Acorn had hoped, overall.)
Another thing is that the Commodore machines also had cartridge slots.
In some senses, the Electron did have a "cartridge slot". The expansion port met that description. But Acorn set two additional expectations:
  • Expansions should provide a follow-on socket for another expansion, and play nice with other expansion hardware.
  • Software should provided via the paged-ROM mechanism.
A board which just slapped a ROM onto the expansion port would have been pretty cheap, but it wouldn't have been nice, and Electron owners had higher expectations, partly by having seen how clean the BBC Micro's expansion architecture was.
But I guess Acorn figured out their inherent utility eventually for the Master 128
Adding cartridge slots to the Master was a mistake. There, I said it. The only thing people ever did with them was add expansion ROMs, and those ROMs were never actually supplied in the cartridges. What did people gain by fitting ROMs to a cartridge then plugging in the cartridge over just lifting the lid and plugging the ROM in directly? Nothing. Especially as if you only wanted the software briefly you'd simply load it into one of the banks of sideways RAM via the disc interface that came as standard.

They could have saved a lot of time and trouble by instead providing a couple of extra ROM sockets. Indeed, on the Master Compact they did precisely that.

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Re: Crazy idea? Downgrade Electron to an Atom? Possible?

Post by paulb » Sat Mar 03, 2018 4:56 pm

crj wrote:But a bigger issue is that, once you have one video output, providing alternatives in the main unit is cheap, and providing them via an expansion port is relatively tricky. Looking at the circuit diagram, once you have the UHF output, adding RGB just needs the socket, a 3-pin header, a quarter of a 74-series quad XOR gate and three resistors. I mean you could feed RGBS to the edge connector and put those components in an expansion, but really?
Well, I wasn't arguing for routing the video signals through the expansion connector, merely pointing out that Acorn could have deleted more stuff from the Electron to save pennies, Sinclair-style, if that was the aim.
crj wrote:Conversely, there were a dozen or so ICs involved in all the address decoding and latching within the Plus 1. But more than that, there was a lot of mechanical engineering involved. As well as the added expense, there was the added development and tooling time. Remember the Electron was being released to a tight schedule as well as a tight budget. Indeed, even without including a cartridge slot, the Electron was late and that ruined Acorn.
It's certainly true that those ICs would have added extra cost, and the Electron's board is far simpler than any of the Beeb models, presumably to take advantage of reduced production costs as well as reduced component costs. But then the ULA needed to get done on time and within budget for this to make any sense. In contrast to that, the mechanical engineering that was probably being done at the same time, anyway, is much less significant or at least better understood. (Amstrad managed to leverage its non-computing expertise satisfactorily, after all.)
crj wrote:More, a case of the BBC Micro having been designed with a very strong focus on the education market, and being much better attuned to their needs. If they'd wanted Electrons to go into schools they should have added not a cartridge slot, not a disc interface, but Econet. But they never did: schools kept buying Beebs, so there was no real point.
It depends. If you're buying whole rooms of machines, Econet is worthwhile, but that was arguably a secondary school market thing. Of course, one can always say that since smaller customers - such as primary schools - aren't buying many computers, why bother helping them save money so that they can deploy machines more effectively? On the subject of schools keeping on buying Beebs, see below.
crj wrote:Remember, also, that in an educational environment the cost of the plastic box full of electronics is only a small proportion of the overall cost of a computer. You also need staff to support them, somewhere to put them, etc. Given the far lower usefulness, the superficial cost saving made no sense. (Indeed, the Electron never made as much sense as Acorn had hoped, overall.)
It all depends on how sophisticated the use of the machines is. Maybe your experiences are different from mine, but at my primary school they had a grand total of two Beebs that were occasionally rolled out to run educational software titles. You could have used something like a games console for that level of sophistication. I imagine that not long after I went up to secondary school, they left these things in the cupboard. (Some people in the teaching profession are still rather displeased at the way computers were brought in as this thing they had to deal with, as well they might be given the way the teaching profession is treated generally by society in Britain.)

Meanwhile, in my secondary school, they had Beebs that also presumably ran educational stuff, were maybe used for BASIC programming before the transition from "computer studies" to "information technology", and actually used some kind of bizarre networking arrangement that had an Apple 2 as the fileserver, at least for the ones that were networked. The school acquired a bunch of Ferranti-branded PCs (maybe these) which were used standalone, and they eventually went the RM Nimbus route with these also not involving a network, and with people using whatever "office" software had been installed on all of those things.
crj wrote:Adding cartridge slots to the Master was a mistake. There, I said it. The only thing people ever did with them was add expansion ROMs, and those ROMs were never actually supplied in the cartridges. What did people gain by fitting ROMs to a cartridge then plugging in the cartridge over just lifting the lid and plugging the ROM in directly? Nothing.
It is all about the usability. "Normal people" do not want to be opening up computers to plug in ROMs. I hated having to do anything with RISC OS upgrades with the 32-bit hardware, with the only time I had to install a ROM with the Electron being when I fitted the *TREK disassembler ROM in the spare slot inside a Slogger Pegasus 400 cartridge. A cartridge system is meant to spare people that kind of hassle.

And the reason nobody really did anything with the Master 128 cartridge slots, apart from Acorn making a few ROM cartridges and others offering "blank" cartridges, was most likely because the Master series was not ever likely to be the focus for independent developers. The likes of Computer Concepts, those who might have done such stuff earlier in the Beeb era, were off doing stuff for the Atari ST at that point.

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Re: Crazy idea? Downgrade Electron to an Atom? Possible?

Post by crj » Sat Mar 03, 2018 6:19 pm

paulb wrote:Well, I wasn't arguing for routing the video signals through the expansion connector, merely pointing out that Acorn could have deleted more stuff from the Electron to save pennies, Sinclair-style, if that was the aim.
Deleting from the spec something which can be provided by an expansion makes a lot more sense than deleting something an expansion can't provide. If the Electron had only provided a UHF video output and not put RGBS on the expansion connector, then nobody could ever have plugged in a monitor. Well, not without soldering directly to mainboard tracks, at any rate!

Compare and contrast with, say, the analogue port. The cost of putting that in the Plus 1 instead of the main Electron is basically the cost of the extra casework.
Maybe your experiences are different from mine, but at my primary school they had a grand total of two Beebs that were occasionally rolled out to run educational software titles.
Ah. We had a dozen model Bs with Econet, one with Econet and floppy and a fileserver with Econet, floppy and second processor. Plus another four stations in the staff computing room, one with a modem in the library, one in the archives office, two in the electronics lab. Then we added an SJ Research file server and a Domesday system. After that, the school switched to Macs while leaving the Acorn infrastructure intact, adding a single A440 for people who needed it.

The computer lab was timetabled for use about two periods in three, by my recollection, and got used extensively by the computer society during breaks and after school.

Those computers got a lot of use, and a lot of pupils learned useful stuff on them. Computing was an available A-level option and plenty of us went on to do computer science degrees.

School admin was done on a PDP-11. When the school upgraded, the old one was wired through to the serial ports of some of the beebs so students could play with RSTS/E.

It seems we may have been at opposite extremes in our experiences.
It is all about the usability. "Normal people" do not want to be opening up computers to plug in ROMs.
With the Master, "normal people" can load ROM images into sideways RAM, though.

Another issue that I've just remembered is that "normal people" also don't want urchins walking off with software cartridges. ROMs installed within a computer that's locked down are rather harder to pinch.

Meanwhile, I followed the instructions to fit a ROM/RAM board in my own Beeb at the age of 14, having first touched a computer only a couple of years earlier. It's not that daunting!

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Re: Crazy idea? Downgrade Electron to an Atom? Possible?

Post by paulb » Sat Mar 03, 2018 8:35 pm

crj wrote:
paulb wrote:Well, I wasn't arguing for routing the video signals through the expansion connector, merely pointing out that Acorn could have deleted more stuff from the Electron to save pennies, Sinclair-style, if that was the aim.
Deleting from the spec something which can be provided by an expansion makes a lot more sense than deleting something an expansion can't provide. If the Electron had only provided a UHF video output and not put RGBS on the expansion connector, then nobody could ever have plugged in a monitor. Well, not without soldering directly to mainboard tracks, at any rate!
Good thing, then, that since I wasn't arguing to remove the video connectors, I also wasn't arguing to route the signals through the expansion connector, either.
crj wrote:Ah. We had a dozen model Bs with Econet, one with Econet and floppy and a fileserver with Econet, floppy and second processor. Plus another four stations in the staff computing room, one with a modem in the library, one in the archives office, two in the electronics lab. Then we added an SJ Research file server and a Domesday system. After that, the school switched to Macs while leaving the Acorn infrastructure intact, adding a single A440 for people who needed it.

The computer lab was timetabled for use about two periods in three, by my recollection, and got used extensively by the computer society during breaks and after school.

Those computers got a lot of use, and a lot of pupils learned useful stuff on them. Computing was an available A-level option and plenty of us went on to do computer science degrees.

School admin was done on a PDP-11. When the school upgraded, the old one was wired through to the serial ports of some of the beebs so students could play with RSTS/E.

It seems we may have been at opposite extremes in our experiences.
We will leave it up to the casual reader as to which experience was more typical.
crj wrote:With the Master, "normal people" can load ROM images into sideways RAM, though.
I'm sorry, but that is still not even approaching the usability that people would have expected, particularly in a primary environment or a secondary environment with no dedicated support people or particularly-interested teachers.
crj wrote:Another issue that I've just remembered is that "normal people" also don't want urchins walking off with software cartridges. ROMs installed within a computer that's locked down are rather harder to pinch.

Meanwhile, I followed the instructions to fit a ROM/RAM board in my own Beeb at the age of 14, having first touched a computer only a couple of years earlier. It's not that daunting!
But again, it's about the "normal people", not the tinkerers amongst us.

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Re: Crazy idea? Downgrade Electron to an Atom? Possible?

Post by crj » Sun Mar 04, 2018 12:33 am

paulb wrote:I wasn't arguing to remove the video connectors
But previously...
paulb wrote:if you're targeting the home market, things like the RGB connector and composite connector are largely superfluous

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Re: Crazy idea? Downgrade Electron to an Atom? Possible?

Post by paulb » Sun Mar 04, 2018 12:56 am

crj wrote:
paulb wrote:I wasn't arguing to remove the video connectors
But previously...
paulb wrote:if you're targeting the home market, things like the RGB connector and composite connector are largely superfluous
Yes, well, if you're going to trim away the rest of the sentence and ignore qualifiers, plus ignore the corresponding feature choices for the Spectrum, then I guess you "win" the argument. Sigh.

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Re: Crazy idea? Downgrade Electron to an Atom? Possible?

Post by richardtoohey » Sun Mar 04, 2018 1:11 am

Discrete (hopefully) cough. Think we are drifting a bit off-topic here, so let's keep in on-topic, please.

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Re: Crazy idea? Downgrade Electron to an Atom? Possible?

Post by myelin » Sun Mar 04, 2018 4:11 am

Back to the original premise... I’m curious how *many* ULA-less Electrons there are out in the wild. Does everyone here have one? I have two working Elks and would be curious to try making a ULA replacement, or trying out Dave H’s board, but I don’t want to touch my working ULAs; anyone got a broken Elk they’d be willing to part with?

The ULA is definitely what you’d want to replace if you wanted to turn an Elk into a Beeb, Master, or Atom...
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Re: Crazy idea? Downgrade Electron to an Atom? Possible?

Post by roland » Sun Mar 04, 2018 8:41 am

It is possible to upgrade an Electron to an Atom by either replacing the ula or the main board. Personally I would create a new main board and add the AtoMMC, more memory and a 6522. But the biggest problem is the keyboard. The Electron has four keys less than the Atom so it will never be 100% compatible.

I guess that the most interesting use of the Atom these days is playing Kees's games but due to the keyboard differences that might be a problem.

But the idea of Wim is also doable. If you modify the atomulator for the pi and use the i/O ports for reading the keyboard then you have a nice prototype for a start.
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Re: Crazy idea? Downgrade Electron to an Atom? Possible?

Post by SteveBagley » Sun Mar 04, 2018 10:07 am

paulb wrote:", and actually used some kind of bizarre networking arrangement that had an Apple 2 as the fileserver, at least for the ones that were networked.
Probably best to move this into a different thread but do yo you have any more details about how this was setup?

Steve

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Re: Crazy idea? Downgrade Electron to an Atom? Possible?

Post by paulb » Sun Mar 04, 2018 10:53 am

SteveBagley wrote:
paulb wrote:", and actually used some kind of bizarre networking arrangement that had an Apple 2 as the fileserver, at least for the ones that were networked.
Probably best to move this into a different thread but do yo you have any more details about how this was setup?
No, sorry. And sorry to the OP for the topic shift.

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