Atari 520ST Expansion options?

[ColecoGamer]

I was a kid when my family owned a 520ST, so I don’t know much about expanding the computer.

 

Since the 520ST has a cartridge port on its side, I would imagine expansion modules existed for it? I keep thinking a RAM expansion module once existed for this expansion port, but my memory on it existing or not is foggy (darn my old age). Lol

 

My 520ST already has a Gotek drive, so I am familiar with its benefits. 
 

I appreciate any responses left; thank you for reading my post!

Edited August 19, 2022 by ColecoGamer

[zzip]

The catridge port was used things like hardware clocks,  digitizers,  scanners (I think?)   I don't recall memory updates for it though.    When I updated my 520ST (fm)  RAM,  my friend just soldiered new chips to the motherboard and it worked.

[zzip]

I also seem to remember that the Macintosh emulators used the cart port to hold the Mac ROMS? 

[ParanoidLittleMan]

Cartridge port is not suitable for RAM expansion - there are no lines for that. It is additionally read only.

I guess that currently NetUsBee is most popular expansion for. Will not go here in what it can.

ACSI port is Atari STs fast data transfer port - so can get diverse adapters which can use SD or even some CF cards as hard disk.

Like UltraSatan, SD4ST, ACSI2STM(SD) ...

RAM, TOS upgrade is also useful, but it can be done only internal.

[Zogging Hell]

3 hours ago, zzip said:

The catridge port was used things like hardware clocks,  digitizers,  scanners (I think?)   I don't recall memory updates for it though.    When I updated my 520ST (fm)  RAM,  my friend just soldiered new chips to the motherboard and it worked.

Yep you are right scanners (my favourite one connected to two light sensitive wires you attached to your dot matrix printer head and then scanned with the printer!) and the Mac emulators did use the port, there were also expansion sound chips (MV-16). I may be wrong but didn't that technics lego kit also use the cartridge port to control the motors, and also possibly that strange radio controlled helicopter game which used a real radio control (what was that called anyone?). There was also an alternative operating system for the ST called SMS2 (or something like that). Although none of these are much use to the OP.

 

Pretty grateful there were no memory upgrades for the cartridge port, the cartridges I had loved coming loose if you moved the machine while in use, and it would definitely be a ZX81 ram pack wobble moment if they did (although with an added risk of frying the ST)...

[mickster]

49 minutes ago, Zogging Hell said:

Yep you are right scanners (my favourite one connected to two light sensitive wires you attached to your dot matrix printer head and then scanned with the printer!) and the Mac emulators did use the port, there were also expansion sound chips (MV-16). I may be wrong but didn't that technics lego kit also use the cartridge port to control the motors, and also possibly that strange radio controlled helicopter game which used a real radio control (what was that called anyone?). There was also an alternative operating system for the ST called SMS2 (or something like that). Although none of these are much use to the OP.

 

Pretty grateful there were no memory upgrades for the cartridge port, the cartridges I had loved coming loose if you moved the machine while in use, and it would definitely be a ZX81 ram pack wobble moment if they did (although with an added risk of frying the ST)...

 

 

the rc helicopter/airplane game is called R/C Aerochopper from Ambrosia microcomputer products.

[Muzz73]

I had a friend that decked out his 520STfm back in the day; 2.5MB RAM, a 4,096 color board, Tweety Board... I can't remember if there was anything else, though.

 

That reminds me... he didn't have a RAM expansion board, IIRC. I think his RAM chips were somehow piggy-backed. Has anyone ever seen anything like this?

[ParanoidLittleMan]

Since this thread topic is Atari 520 expansion options, it is normal to rather talk about currently available and interesting, useful expansions. As cartridge port was mentioned, most of replies focused on what was available for it in past.

I think that should rather talk about what is now available. I already wrote about mass storage solutions with modern Flash cards. And NetUsBee is one of it too, with LAN, extra USB/PS2 mouse port.

And surely RAM expansion is what is probably most useful/needed for one ST 520 now.   Here few words about expansion ports on 8-bit computers and on Atari ST:

What was on Sinclair ZX 81 and Spectrum was basically full CPU bus + some other lines. So, it was good for RAM expansion, and ZX 81 was pretty useless without it, because was with only 1 KB RAM - yes, you read it correct. So, I bought 16 KB expansion together with machine. It worked pretty reliable.  In case of Spectrum I bought 16 KB model, and did RAM expansion to 48KB self - there is place for it on motherboard.

It is possible to add for instance IDE hard disk port via Spectrum expansion port:   http://zx48.8bitchip.info/idehard.htm

you may see on schematic ZX Edge connector lines - plenty of them, and good for practically any expansion.

This is not case with Atari ST cartridge port - it was intended for ROM cartridges, max capacity 128 KB - that self means that is not good for TOS upgrade (should be min 256 capacity) . Then, it is read only. Despite it, lot of adapters for cartridge port solved write. As it was with my first HW design for Atari ST:  cartridge port EPROM programmer. It surely needed write - was solved by using address lines as data with help of extra HW logic. 

Now, with same type trick write to external RAM via cartridge port is possible too. But it was not made at all, from simple reason: it would be slow, and more important: there are not all needed address lines, so it could not work as normal RAM on CPU bus, maybe only as some kind of RAM disk, not usable for running of SW .  Btw. there is something like it, still available:  http://atari.myftp.org/stramcart/stramcart.html

It is mostly in Polish, but you can see what about it is. At bottom is English text by me about usage of my program RAMCART for it. Yes, you guessed: user can have ST ROM cartridge equ. device without need to have EPROM programmer - can change content of RAM on it with Atari and special SW for it. Battery on device will keep content ..

[ParanoidLittleMan]

25 minutes ago, Muzz73 said:

I had a friend that decked out his 520STfm back in the day; 2.5MB RAM, a 4,096 color board, Tweety Board... I can't remember if there was anything else, though.

 

That reminds me... he didn't have a RAM expansion board, IIRC. I think his RAM chips were somehow piggy-backed. Has anyone ever seen anything like this?

I made my first RAM expansion in my 520 ST to 1 MB, using that piggy-back system - just adding same RAM chips on top of existing ones, and of course needed few wires too.

But later I wanted more RAM, so added 2 MB to 512KB on board to have 2.5 MB RAM. It was in 1989 - and piggy back was not really usable because of different RAM chips, with different pinout. So, I made PCB for RAM expansion, and it was small enough to place it easily in ST . Surely needed lot of connections with wires.

Someone other can answer better than me what RAM expansion boards are now available for ST machines. And they may not fit in every ST motherboard revision ..

[ColecoGamer]

This looks promising:

https://www.ebay.com/itm/394104125181?mkcid=16&mkevt=1&mkrid=711-127632-2357-0&ssspo=eum2xomzq6o&sssrc=2349624&ssuid=YT3epDNRT52&var=&widget_ver=artemis&media=COPY

[TGB1718]

3 hours ago, ParanoidLittleMan said:

I made my first RAM expansion in my 520 ST to 1 MB, using that piggy-back system - just adding same RAM chips on top of existing ones

I still have that in my 520STM

It's not a pretty sight, but it does work

[xorcerer]

My friends who did expand my 520 STm about 30 years ago, were very kind to take up the challenge and fixed a ball of dangling wires inside it quite recently. They updated the RAM expansion (switchable 2MB/4MB) ripping out two old ones - a literally hacksawed SIM that was really bad, but looked innocent, and a big mess of wires that was actually a quite decent engineering trick, given the time period and possibilites we had back then.

 

They managed to preserve a soldered in Microdeal 8bit stereo compatible, COVOX-like sound extension, a non-standard overscan hack, and 16 mhz WDC1772 mod that allowed reading HD diskettes. Also, there's a socket soldered on top of 68000 that was specifically prepared to accept an 8086 compatible processor (NEC V30) hardware extension, that allowed execution of IBM DOS. I still have it, and it will make a good video talking about that sometime this year. I'm not sure if that is usable in PC-DITTO, because that was a software emulator. I remember having floppies with "PC-DITTO" label on them, maybe there's an answer.

 

later edit: thanks to @ParanoidLittleMan 's above link (currently inactive, but that website is working) and "Sack" signature on the old PCB, I guess this may be "PC-SPEED":

 

http://atari.myftp.org/atari16bit/pcspeed/pcspeed.html

 

 

Edited January 16, 2023 by xorcerer
photos added