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Hi guys, I totally understand that presenting in a foreign language is really tough (have done it myself). Hopefully, no one minds me asking though?

I'd love to be able to compensate people for their time but the group doesn't have any sponsorship (frankly the group is still too small and niche to attract sponsors).

My Enterprise knowledge isn't yet at the point where I think I could give a useful talk myself - maybe sometime in 2021 I'll get there though :)

I'm the organiser for the London Retro Computing meetup group: https://www.meetup.com/London-Retro-Computing/

Since all events are currently via zoom, the "London" bit of the name isn't really important at the moment :)

I'm always looking for people willing to give talks or demos. We've not had anyone give an Enterprise related talk yet so if you have something you'd like to talk about or demo please let me know. It doesn't have to be a long talk. I'd like to organise an event with several short talks once I have enough volunteers.

Wanted / Re: EP with working 08-47 Nick
« on: 2020.October.25. 18:19:58 »
In the meantime, does anyone have any hints or tips for removing the heatsink on my Nick chip so that I can try to replace it with a better one?

I'd be interested in knowing what heatsinks people are using. I'm trying to get a bare Enterprise 64 motherboard back to working condition and it has no heatsinks on the chips at all.

Interface / Re: Internal memory expansion
« on: 2020.October.17. 19:56:23 »
the Enterprise was created as a multi-session computer, even there are some tasks that can be stopped while doing others.

The more I learn about the Enterprise the more impressed I become. The hardware and solftware feel in a different league from the likes of the ZX Spectrum (the computer I grew up with).

Interface / Re: Internal memory expansion
« on: 2020.October.17. 19:53:45 »
The surface mount (SMT) compnents were all factory (i.e. robot) installed by the board manufacturer ... that is why I wanted to create a simple single-sided board design. I certainly couldn't solder those small components myself either!  ;)

The two 0.1" headers male headers for EXP1 and EXP2 do still need to be soldered onto each SRAM board by the purchaser.

Excellent! Please sign me up for one. I've no problem soldering non-SMT stuff.

Now, it might not be too difficult to extend what I have done and make a 1.5MB internal RAM expansion board, which could then use an external Symbiface3 to give a full 4MB of memory (3.5MB RAM and 0.5MB ROM) ... but how many people would really want such a board?

Hmmmm :ds_icon_cheesygrin:

Interface / Re: Internal memory expansion
« on: 2020.October.16. 08:50:28 »
And second, because there has always been the challenge of knowing if it would be possible for EXOS to reach the maximum of 4MB of addressable memory that was promised....

It would be very cool to see an Enterprise with the full 4Mb.  I still need to get my Enterprise motherboard working and wired up with a keyboard, maybe a project for after that...

Interface / Re: Internal memory expansion
« on: 2020.October.16. 08:48:15 »
The 512KB of SRAM shows up as expected in banks $C0-$C3, $C8-$CB, $D0-$D3, $D8-$DB, $E0-$E3, $E8-$EB, $F0-$F3 and $F8-$FB.


I have another 8 spare memory boards available if anyone wants one, and it looks like 1 of those is already committed.

I would definitely be interested in one. Are these the bare boards or are the surface mount components attached? My soldering skills are probably not up to soldering surface mount components.

Programming / Re: EXOS source code?
« on: 2020.October.04. 20:30:14 »
Thanks for all the responses.

Some direct links (the first one is in Hungarian, but in HTML format, so can be easily Google-translatet):

Cool, thanks. It appears to be incomplete though.

The second one is in Hungarian as well, a scanned PDF, no OCRed, so a bit difficult to translate:

Yeah, that's going to be a little tough for me :)  My Hungarian knowledge is still extremely limited even after some hours on duolingo. :|

I have a partial disassembly (in English) that I made for fun a few years ago. It's probably 25% done. I worked out where the main bits were - reset code, WP, device drivers, BASIC functions etc. (The EXOS ROM actually contains some of the code for BASIC!) But I didn't get around to sorting out all the data or annotating everything. Unfortunately I don't have access to it at the moment, but I'll try to get hold of it and tidy it up so it's useful to someone else.


Not as sophisticated as emulation, but several modern Z80 disassemblers will try to sort the code from the data automatically. In fact, I seem to remember that the EXOS file analyzer - http://epbas.lgb.hu/ - works out which is code and data.

I'll have a go running epbas on the ROM image. I might as well try skoolkit too.

Programming / EXOS source code?
« on: 2020.September.27. 23:04:48 »
Did anyone ever produce an annotated disassembly of the EXOS 2.x ROM? I've had a bit of a look, but not found anything. The Spectrum community has http://www.primrosebank.net/computers/zxspectrum/docs/CompleteSpectrumROMDisassemblyThe.pdf but EXOS appears to be a far more interesting system and I'd like to know more about the internals.

I'm aware that I could put a ROM image through a disassembler, but then I'd have to know what parts of the ROM were data and what was code and I'm curious whether anyone has already done that work and been kind enough to annotate the disassembly.

There's a neat disassembler toolkit for the Spectrum world (https://github.com/skoolkid/skoolkit) that uses profiling in an emulator to work out what is code and what is data. Do similar tools exist for the Enterprise?

Interface / Re: Internal memory expansion
« on: 2020.September.27. 22:52:24 »
The boards have arrived from China ... now I've got to wait for the headers to arrive, and then I've still got to wire up an RGB cable for my monitor before I can actually make sure that these work (or not)! ;)

(Attachment Link)

Any luck? Did the expansion work?

Interface / Re: Internal memory expansion
« on: 2020.September.18. 07:46:17 »
It is more of a habit. I usually replace every 7805 in old computers either with the OKI-78SR or the TSR 1-2450 in order to reduce the heat. I generally prefer the TSR 1-2450, but they don't fit in the EP without removing the cooler and that would leave an ugly hole.

Thanks for this. I suspect there is an issue with one of the 7805s on my enterprise and was planning to replace both with new 7805s but will use OKI-78SR now.

Interface / Re: Internal memory expansion
« on: 2020.August.30. 19:30:15 »
At startup, the EXOS ROM tries writing to each segment to check if there is RAM there. The hardware doesn't provide any extra information, it's tested by software.

Thanks geco & dangerman

Interface / Re: Internal memory expansion
« on: 2020.August.30. 13:33:30 »
One thing I've not yet understood is how the Enterprise senses the amount of RAM available. Does it probe memory on startup or is there logic in the RAM expansion to indicate how much RAM is present?

Interface / Re: Internal memory expansion
« on: 2020.August.29. 19:35:14 »
I've placed an SMT production order at JLCPCB, and should hopefully receive the populated boards in a few weeks.

Cool, what's the minimum order quantity?

If it works in my EP64, then I should have a few spare boards to sell on to anyone that wants one.

I'd definitely be interested

Hardware / Re: What internal RAM expansion?
« on: 2020.August.16. 23:02:39 »
The SF3 is interesting, but it seems to offer far more than I'd personally want.

As someone that recently bought one of the new/almost-new Enterprise 64 machines that have been unearthed in Egypt, I just want some more internal memory, and Szorg's lovely SD card adapter.

Exactly my situation too. Looks like we bought from the same seller.

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