An Atari Mega STe in a 520ST body?

Рет қаралды 2,358

2 ай бұрын

In this video I take a look at an Atari 520ST with a nifty accelerator from 1989. I get it running and test it versus other ST's.
#retrocomputing
#vintagecomputing
#atari
#atarist

Пікірлер: 37

@SillySausage-mq3so 2 ай бұрын

Had a 520 and 1040 Atari ST, gave both away, when I went to my Pentium 75 PC, had fun with my ST, good old days.

@jfloydsea 2 ай бұрын

Nice upgrade! I didn’t know there were options for adding a blitter to boards that didn’t have a socket.

@pandacongolais 2 ай бұрын

The damage under the ROM chips may come from a ROM swap. My first ST, a true ST like yours, with external power supply and floppy drive, had no TOS ROMs. It had 2 ROM chips for a boot loader, the TOS itself was on floppy. Imagine a poor 512 kB ST, loading the TOS, then the usual desk accessories at the time, then the Atari BASIC ... 4 kB was the remaining RAM space you had left for your program ! In 1986, it was only 4 times my ZX81. Except that I had the 64 kB memory pack for this one ... 16 times less on the ST than on the ZX ! I know how it feels because, I bought a 1040 ST, but it had to be serviced +/- 10 times. After one of these, it was showing only 512 kB ... Yeah, one more commute to the shop ... I'll regret all my life selling it ... But it was to buy an STe, boosted to 4 MB ! Yes ! I never got a HD for the ST, only for the STe, which sits above my desk, with its mono and color monitors, and the gigantic and noisy Seagate 330 MB 5"1/4 full height HD from a friend ...

@powerofvintage9442 2 ай бұрын

I agree that there was likely a ROM swap in it's past. The 512kb is fine for the early software and games, but to run anything from a hard drive, more is needed.

@michaelyork4554 2 ай бұрын

I had a 1040 ST, I remember that the power supply failed after a couple years, and I got a multi output DC supply from work and wired it in and got a couple more years out of it. Now I wish I would have kept it, like the Intellevision I used to own.

@powerofvintage9442 2 ай бұрын

That's a very common story. I clearly remember the day I gave up my original 520ST...I'm still kicking myself

@bobobear1977 2 ай бұрын

On a 68000 system, you're gonna need an auto folder program to initialize the FPU for you. The 68000 doesn't have Line-F, so it doesn't know about the 68881 being there. The communication with the FPU is all done through PAL chips on the accel board.

@powerofvintage9442 2 ай бұрын

I'll see if I can find a program / driver to enable the FPU.

@stephenwhite506 2 ай бұрын

I believe a FPU on a 68000 needs to be directly mapped into the address space. So software will need to know what address that is.

@thetechnoshed 2 ай бұрын

ROM acceleration will be very noticable on the desktop -- all OS function will run at 16MHz. It's a nice boost. Very few games will benefit as few use the OS functions. Frontbench certainly won't. I have a video showing exactly how many OS calls Frontier uses by having it flash an LED. The bodge wires on the back of the CPU socket will be the bus arbitration lines for the blitter -- it's a DMA device. The 68k had no coprocessor control lines so the FPU will be mapped into address space like that of the MegaSTE. Hardly any software is compiled for this 'peripheral' FPU mode, as the 'coprocessor' mode was virtually ubiquitous. If you have a dig around on the Exxos or Atari forums there was some work done about a year and a half ago to provide a TSR program that hooked the coprocessor calls and redirected them to the MSTE peripheral address. Might be worth testing that? Prove it works on the MSTE before trying on this as -- who knows -- the mapped address may be different. Not sure the MSTE was out when this accelerator was built so they may not have had anything to copy.

@powerofvintage9442 2 ай бұрын

This accelerator came out in 1989, so pre Mega STe.

@danielktdoranie 2 ай бұрын

Could you increase the RAM or swap out the processor on the accelerator with a 50MHz 68030?

@powerofvintage9442 2 ай бұрын

Yes, I could upgrade the RAM and am considering it. This accelerator only works with 68000 CPUs, so I couldn't just upgrade the CPU. To get a 68030 working would need a different accelerator (TF536 / ST536).

@keven628 2 ай бұрын

Nice!

@FXGreggan. 2 ай бұрын

Wish I could find a new kbd membrane for my ST so I can enjoy its upgrades :/

@powerofvintage9442 2 ай бұрын

For the Atari ST there shouldn’t be a membrane at all for the keyboard. They use a PCB and rubber domes. I’ve not had one keyboard in the dozens I’ve worked on that couldn’t be fixed with either a cleaning or new domes at the worst. I could see in a really bad case a broken trace on the keyboard PCB but they should be pretty easy to track down and fix.

@FXGreggan. 2 ай бұрын

@@powerofvintage9442 You're absolutely correct, remembered wrong about the flexfilm, had to open and check :) Also a good time for that cleaning, but to no avil, like a third of the keys are totally dead, suspecting bad chip as I checked all traces and solder joints under microscope, dang it. Thanks for your videos anyway! Always fun to watch some Atari hardware.

@DeadCat-42 2 ай бұрын

I have a creative upgrade board ,. I have no instructions.(Or a blitter chip) Any idea how to hook it up?

@powerofvintage9442 2 ай бұрын

Send me a photo of it and I can help out. If it's the same one as mine, I'm pretty sure I understand enough to get you to a point of replicating what I have working on mine. Use the contact email for the channel.

@DeadCat-42 2 ай бұрын

@@powerofvintage9442 ok, thanks! I have a beat up old ST board with a dual rom kit and tweety board , but I was 15 and not very good soldering so it's pretty bad. I was going to use it as a test. I have a 1040ste and an STfm. I also have a couple atari SCSI adapters and a bunch of old drives I need to check for files and working software. I want to go through my software collection and make copies before the disks degrade. I have a LOT (hundreds) of disks and a lot of them are copy protected so I'm going to make a blitz cable and have an old school copy party. I wish i still had my 8-bit.

@DeadCat-42 2 ай бұрын

@@powerofvintage9442 Thank you, and yes , All those modifications were as delivered, I bought this new and never installed it because my CPU was soldered in and I was 15.

@DeadCat-42 2 ай бұрын

I know the creative has some buffering and other things that improved speed more than just the 16MGhz clock on the cpu.

@Fularu 2 ай бұрын

It can't be a Mega STe without the new sound chipset. It's basically an accelerated Mega ST (since these had a blitter socket with the Mega ST2 and up versions)

@powerofvintage9442 2 ай бұрын

Yes, I agree...it also doesn't have the updated shifter with slightly improved colors of the STe. I'm focused more on the benchmarking comparisons as the Mega STe had the 16mhz CPU clock speed and the blitter together.

@ecdhe 2 ай бұрын

Is there any software on the ST which takes advantage of an FPU?

@powerofvintage9442 2 ай бұрын

There is some CAD software that does...as well as the benchmarking software ;). No software I ever used as a kid used an FPU to my knowledge.

@ecdhe 2 ай бұрын

@@powerofvintage9442 the FPU came in late for STs (even the TT didn't have one), so it's not surprising you never used one which used an FPU - I certainly didn't. But it would be cool if a modern version of the GFA Basic could use it - THAT I could have used back in the day!

@ecdhe 2 ай бұрын

@@powerofvintage9442 after some research, it seems like some versions of GFA basic support the 68881 FPU (but not the 68882). For the record, back in the day I computed some fractals on my ST using GFA Basic (using its compiler). One particular fractal took 14 hours to compute. An FPU sure would have been handy back then.

@TheJeremyHolloway 2 ай бұрын

@@ecdheno, it’s due to FPUs having been expensive back then. Atari sold a 68881 board for the Mega ST. So FPUs didn’t come “late” to the ST. FPU support was much better on the Macs than on either the Amiga or the ST platforms.

@ecdhe 2 ай бұрын

@@TheJeremyHolloway Thanks for the details. I must admit I never heard of the FPU for the ST while I had one (1985-1991). I remember reading about the Blitter, but not the FPU.