NeXT prototypes and hardware variations

[andreas_g]

Hello all,

it turned out recently, that NeXTStep 2.0 has the ability to run on a never released prototype of the NeXTstation Color. That prototype obviously had a different memory layout, where the VRAM is located at address 0x06000000 instead of 0x2c000000.

Furthermore the headers that come with NeXTStep indicate that there are non-Turbo NeXTstations and NeXTcubes with a revised main board (rev. 1) that utilized the new clock chip (MCCS1850).

Finally I read somewhere, that later versions of the non-Turbo NeXTstations had a different memory layout and supported up to 128 MB RAM. Unfortunately I don't remember where I read that.

Now I'd like to find out here, which of these really existed, what other prototypes or variations are known and what special characteristics they had.

[cuby]

Some people seem to own NeXT prototypes:

• https://www.youtube.com/watch?v=u74m8RpjIDI (around the 4 minute mark, serial #214
• https://www.journaldulapin.com/2014/09/01/prototype-nextstation/ (serial #262)

Both machines seem to be mono non-Turbo slabs, but it seems that they have different layouts for the "ZIP" video RAM chips.

Now the prototype I would really love to see is a (working) 88k-based NRW .

[mikeboss]

Finally I read somewhere, that later versions of the non-Turbo NeXTstations had a different memory layout and supported up to 128 MB RAM. Unfortunately I don't remember where I read that.

these were simply turbo main logic boards running at only 25 MHz.

[Nitro]

Hello all,

it turned out recently, that NeXTStep 2.0 has the ability to run on a never released prototype of the NeXTstation Color. That prototype obviously had a different memory layout, where the VRAM is located at address 0x06000000 instead of 0x2c000000.

Furthermore the headers that come with NeXTStep indicate that there are non-Turbo NeXTstations and NeXTcubes with a revised main board (rev. 1) that utilized the new clock chip (MCCS1850).

Finally I read somewhere, that later versions of the non-Turbo NeXTstations had a different memory layout and supported up to 128 MB RAM. Unfortunately I don't remember where I read that.

Now I'd like to find out here, which of these really existed, what other prototypes or variations are known and what special characteristics they had.

There's some information about the later versions here:

https://www.nextcomputers.org/NeXTfiles/Articles/NeXTWORLD/NeXTWORLD_Extra/92.10.Winter.NWE/92.10.Winter.NWExtra08.html

[andreas_g]

Thank you for these interesting details! Does someone in here own a non-Turbo NeXTstation or NeXTcube with new clock chip? It would be interesting what it reports for SCR1 and SCR2 (ROM Monitor > s).

[Nitro]

Thank you for these interesting details! Does someone in here own a non-Turbo NeXTstation or NeXTcube with new clock chip? It would be interesting what it reports for SCR1 and SCR2 (ROM Monitor > s).

Here's a non-Turbo 25MHz NeXTstation with the new chip set.

[andreas_g]

Here's a non-Turbo 25MHz NeXTstation with the new chip set.

Not exactly what I was looking for but still very interesting! Thank you for this! This is obviously one of those "non-Turbo" machines with higher serial numbers. As mikeboss mentioned above, this seems to be in fact a Turbo with slower CPU. There seem to be no other differences, even the board revision is identical.

Now I wonder if there are real non-Turbos with the old chipset but with new clock chip around. They are mentioned in the headers and seem to be supported by the software, even 2.0, but probably never made it to the wild.

[Nitro]

Oops, my bad. I misunderstood what you were looking for. I'll see if I have any non-Turbos with the new clock chip.

[andreas_g]

Oops, my bad. I misunderstood what you were looking for. I'll see if I have any non-Turbos with the new clock chip.

Anyone found one of these? Probably they were never shipped.

[Nitro]

I don't have any boards with clock chips specifically marked MCCS1850. I do have one of the early mono non-turbo NeXTstation boards with a MC68HC68T1 chip, different board layout and a socketed engineering sample CPU. The other non-turbo mono NeXTstations are the newer boards with soldered CPUs and XCCS1850DW clock chips. I don't have any prototypes. You might ask @eagle as I believe he has a prototype cube.

[andreas_g]

I don't have any boards with clock chips specifically marked MCCS1850. I do have one of the early mono non-turbo NeXTstation boards with a MC68HC68T1 chip, different board layout and a socketed engineering sample CPU. The other non-turbo mono NeXTstations are the newer boards with soldered CPUs and XCCS1850DW clock chips. I don't have any prototypes. You might ask @eagle as I believe he has a prototype cube.

I suppose those newer "non-Turbo" boards with soldered CPUs are the ones mentioned above with Turbo-chipset but 25 MHz CPU?

[Nitro]

The newer boards I was referring to have the non-turbo chipset with 30 pin memory, XCCS1850DW clock chips and soldered CPUs. Here's some pictures to help clarify the different boards. You can see the date codes on the floppy drives. I hope that helps.

25MHz mono non-turbo chipset early board.




25MHz mono non-turbo chipset newer board.




25MHz mono turbo chipset board.




May as well show them all.
33Mhz mono Turbo NeXTstation

[andreas_g]

That newer board with non-Torbo chipset and new clock chip is exactly what I was looking for. Would you mind to read the system registers (s) from ROM Monitor on one of these?

A little fun fact: Motorola normally named their chips MC... but it seems in NeXT hardware we often see XC... on the chips.

These might be some kind of early samples. For example XC68040 uses a different stack frame than later MC68040. Toni Wilen, who works on 68k CPU emulation for WinUAE, told  he has never seen one of these in any other system.

So XCCS1850 must be some early version of the MCCS1850.

[Nitro]

I can do that, give me a minute to get a monitor set up. Yes, I believe Motorola used the X prefix for chips until they were qualified, then changed them to M. If you look closely at the early board the DSP56001 chip is marked XSP56001. Also, the engineering sample CPU is marked PC68040RC-A.

[andreas_g]

I can do that, give me a minute to get a monitor set up. Yes, I believe Motorola used the X prefix for chips until they were qualified, then changed them to M. If you look closely at the early board the DSP56001 chip is marked XSP56001. Also, the engineering sample CPU is marked PC68040RC-A.

Interesting! I just found this page. There are some details on how the chips were labeled and of course you are right: XC means not fully qualified pilot production part. Btw. NeXTstep 2.0 only supported those early versions with different stack frame (FPU version 0x40). It won't run on later versions (FPU version 0x41).

Maybe once you have the NeXTstation running you can also check the memory layout, just to be sure (ROM Monitor > m).