NOXROM Cartridge

For experts to discuss very technical stuff and newbies to ask why the Spectrum they bought off ebay doesn't work.
User avatar
RMartins
Manic Miner
Posts: 776
Joined: Thu Nov 16, 2017 3:26 pm

Re: NOXROM Cartridge

Post by RMartins »

It would be interesting, to know, how many developers would be interested in having a sample cartridge, to play around, and make a game exploring the new possibilities.
hikoki
Manic Miner
Posts: 576
Joined: Thu Nov 16, 2017 10:54 am

Re: NOXROM Cartridge

Post by hikoki »

RMartins wrote: Mon Feb 12, 2018 7:32 pm
hikoki wrote: Mon Feb 12, 2018 11:08 am Could 128K games be converted on the fly from original cassette tapes?
in some way that audio output from cassette player can be transformed by the interface
Maybe you are dreaming too much :)

The Cartridge is just a ROM(FLASH) device, with paging capabilities.
It's not an interface per see, just a cartridge.
I would rather take my coffee with Sincclairin instead of Sugar. I've been told that it is impossible to plug anything into a 48k machine to convert it to 128K. It is necessary to open it and disconnect the upper 32K RAM.

This reminds me of one idea for a toy cartridge on the speccy.org forums, something with speaker like those used in greeting cards :mrgreen: Mcleod_ideafix suggested the idea of playing one tap/tzx from some STM32F0 microcontroller with 256KB flash : http://uk.farnell.com/stmicroelectronic ... dp/2488281
User avatar
RMartins
Manic Miner
Posts: 776
Joined: Thu Nov 16, 2017 3:26 pm

Re: NOXROM Cartridge

Post by RMartins »

hikoki wrote: Mon Feb 12, 2018 9:21 pm ---
I've been told that it is impossible to plug anything into a 48k machine to convert it to 128K. It is necessary to open it and disconnect the upper 32K RAM.
...
If you really want to do that, you can start with a 16K Spectrum, and then add an external interface with the required RAM and paging registers to make it "compatible" with a 128K version.
However, besides RAM addressing, you would have other concerns to work around, like the dual ROM, not having an AY, Sinclair joystick ports or serial line capabilities.

It all depends exactly what you are trying to do, and to what extent you want it "compatible".
User avatar
RMartins
Manic Miner
Posts: 776
Joined: Thu Nov 16, 2017 3:26 pm

Re: NOXROM Cartridge

Post by RMartins »

I have been thinking on something for some time, which is to find a way to make use of the actual extra memory on a ZX Spectrum 48K.

To save some bucks, ZX spectrums use 8 times 64Kx1 bit memory chips, but they either user the lower or the upper part of the chip (only 32K, since the other part is flawed, hence why it was cheaper), and all chips must be identically flawed (upper or lower) in the same computer to be able to work.

However, it's possible to buy a new set of 64K memories, that are not flawed at all.
So with some clever trickery, we could eventually use the extra 32K available, transforming the 48K into a 80K computer :)
hikoki
Manic Miner
Posts: 576
Joined: Thu Nov 16, 2017 10:54 am

Re: NOXROM Cartridge

Post by hikoki »

^^^
Sounds good.. you mean an interface to make Sinclair macines manage up to 80K? I assume games which are based on that limit would work on Amstrad machines too
User avatar
RMartins
Manic Miner
Posts: 776
Joined: Thu Nov 16, 2017 3:26 pm

Re: NOXROM Cartridge

Post by RMartins »

hikoki wrote: Mon Feb 19, 2018 5:43 pm ^^^
Sounds good.. you mean an interface to make Sinclair macines manage up to 80K? I assume games which are based on that limit would work on Amstrad machines too
Most probably it will not be an interface, since you have to manage the following (t least):
- replace high memory with new 64K 4116 chips, that are completely good
- rework some of the internal decoding logic, to support the extra memory
- support some kind of paging register

But this is a limited solution, because most people will not want to mess with the internal guts of their 48K machine.

But this could provide some interesting features, like a shadow screen for a 48K (80K) :)
User avatar
Seven.FFF
Manic Miner
Posts: 735
Joined: Sat Nov 25, 2017 10:50 pm
Location: USA

Re: NOXROM Cartridge

Post by Seven.FFF »

I remember something in a mag, back in the day (possibly Tim Hartnell or Toni Baker?) teasing access to 80K. I saw a reference to it recently, but I can't find it now.
Robin Verhagen-Guest
SevenFFF / Threetwosevensixseven / colonel32
NXtel NXTP ESP Update ESP Reset CSpect Plugins
User avatar
RMartins
Manic Miner
Posts: 776
Joined: Thu Nov 16, 2017 3:26 pm

Re: NOXROM Cartridge

Post by RMartins »

Seven.FFF wrote: Mon Feb 19, 2018 8:12 pm I remember something in a mag, back in the day (possibly Tim Hartnell or Toni Baker?) teasing access to 80K. I saw a reference to it recently, but I can't find it now.
I believe this could be it, the SP80 (an interface to add 2*32K to a Spectrum 16K).
https://archive.org/details/your-spectr ... 9/mode/2up
Post Reply