Can't identify several model II/16/6000 cards

[NeXT]

Along with several systems we are currently selling (and I beleive they have all since been sold), there was a box of loose boards. I can identify a few of them:

1: Display card
2: Single channel MFM hard drive controller
3: Three port terminal card
5: M68000 board #1
6: M68000 board #2


Boards, 4, 7, and 8 I can't identify.
There were also a few duplicates of some of th boards, on two of the M68000 memory boards the memory is all stacked up. Would this indicate the memory was upgraded to 512k?

 

[kb2syd]

Were these all in one system? I don't think 4 and 8 can coexist.
4 is the old style external hard drive controller. Works with the 8MB drives only.
7 is the Bernoulli Box controller (would control up to two 10 meg drives).
8 is the middle style of hard drive controller. Works only with the 5MEG, 12 MEG and higher external drives. Frank Durda IV has a great refernce on this. See http://nemesis.lonestar.org/computers/tandy/hardware/storage/mfm.html.

As for the memory, if there are 2 256k chips on top of each other, then the board is 1MEG @ 8 bit or 512K at 16 bit (I think). There were hundreds of different memory mods and boards for these machines. I have one that has 4 meg of SIPPS soldered in place. Tandy always referred to the amount of memory at 8 bit addressing even though the 68000 was running in 16 bit.

 

[NeXT]

No, they were not all in one system. They were in a box separate from everything else.
I know for a fact that the system had a memory limitation of 1mb and anything more required a quirky workaround in the OS.

 

[kb2syd]

I know for a fact that the system had a memory limitation of 1mb and anything more required a quirky workaround in the OS.

Did I say anything about it not needing modifications or workarounds? There were several readily available fixes to allow the system to use 1 MEG RAM for process and the rest for SWAP. With the MMU mod, Xenix used multiple megabytes quite easily. Sheesh. I used to manage an istallation of 6 of these machines that ran the company I still work for.

See the following thread. http://groups.google.com/group/comp...en&lnk=gst&q=Xenix+Snapp+RAM#9a4942d115fe1de2

And as far as memory configurations, I know of the original 68000 memory boards that would take from 16k to 64k chips, 4 banks of 8 or nine (depending on how you set the jumpers, parity was there or it wasn't). I think the machine supported up to 3 of these. Then Tandy issued boards (and modifications to the 16k boards) so they could use 256k chips. Then you had Bob Snapp's and Sound America's various memory boards. Maybe hundreds of variations is a bit of hyperbole, but there were many different ways to populate the memory in the II, 12, 16, 6000 line. Minimum was 16k running CP/M, theoretical max was 8Meg using Xenix. Practical limit with the MMU mod installed was 4 meg.