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TransEra 764-RAM Auxiliary Memory for Tektronix 4052/4054 Computers

nikola-wan

nikola-wan

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Here are the EPROM and PAL file captures for this board (I didn't get the actual auxiliary memory - just this ROM Pack):

TransEra 764-RAM Auxiliary Memory ROM Pack EPROM and PAL file captures

Here are some photos of the ROM pack board:

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I have the Auxiliary Memory Manager Operators Manual.

Is there any interest in me scanning that manual?

I don't have the Auxiliary Memory, so I can't test this module.

I got the whole series of TransEra manuals from Stan Griffiths - about 18 years ago, now I have some of the TransEra cartridges.

The most used cartridge so far is the Super Utilities - which has tape block read and write commands - which I am using to recover old Tek 4050 tapes.

Monty
 
I disassembled the firmware for this pack (thanks Monty for making this available ) and spend half a day going through it : if you disregard the DMA options, then the whole circuitry exists of 3 programmable counters ( two 8 bit and one 4 bit) and the memory itself. That's all....
The firmware implements a complete filesystem for the 4052/4, and with moderm memorys and a batterybackup this would be all that those without a 4907 need for a megabyte of offline storage ! There is some logic analyzer work waiting for me..

Jos
 
Spent some more time with the dissassembly, and it seems to be feasible to put it all into a rampack. Here is the result :
F_rampack.jpg

Unlike my previous pack rebuilds this will need some update of the Transera firmware, therefore it will be considerably longer until I can offer something. If successfull it would form a 512K auxilliary RAM, in which the Transera firmware implements a filesystem. A USB interface will allow to store & load the contents of the Rampack as a whole. Transera's DMA functionality is not implemented, the firmware space that frees up will be used to implement USB backup.
Sorry, 4052/4(A) only, not because of the design, but that is what the Transera firmware does. A 4907 remake may be more versatile, but the commands that are implemented there are only partially documented, which makes for a lot of reengineering effort...
 
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Jos,

Great work!

If you are going to modify the Transera firmware - could you initialize the SRAM with files from a micro SD card when the CALL "INIT" is executed? That way the micro SD card could contain the programs and data files to access - as the SRAM will initially be empty when first powering on the system?

I would be able to create the files for the SD card with a customized menu program from my program archives.

In screenshot below - my 4907 floppy disk formatted capacity is 630K and I've used 319K (half the capacity) for only 8 programs.

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If you modified the Aux firmware CALL "INIT" to add one optional numeric parameter - the user could load different images from the SD card with a single call.

Example:

CALL "INIT",4 could load the Adventure files into Aux memory
CALL "INIT",5 could load the System Tape files into Aux memory

The SD Card could hold my entire archive of programs, where different folders contain each of the different archive folders with the addition of a MENU program :)

And CALL "INIT" with no parameter could initialize the memory with no files - like the current TransEra firmware.

As a bonus - with your MFM ROM Pack in one backpack slot and the Aux Memory in the other slot - your favorite CALL "INIT",4 and even CALL "MOLD",1 can be saved in the RTC SRAM so the selected folder and MENU program are automatically loaded on power on!

I would mark the program files as write protected, but the user could write files (like Adventure allows you to save ten different numbered game files).

Actually - no need to mark program files as write protected, you can always type CALL "INIT",X again to reload them from SD Card!

Monty
 
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SD cards are somewhat difficult in that they take a large proportion of the available PCB real estate, even as a micro-SD card. That would necessitate SMD IC troughout the design. It barely fits as it is now. The firmware part has to be in a MFM cart, as there is no more room for a local Eprom !

My idea would be to have 2 new commands RDUSB <name> and WRUSB <name> which would read / write the totality of the AUXRAM, via USB, to an imagefile <name> on the PC. Each named USB imagefile would be the equivalent of a 512K floppy. The Transera fileformat is well defined, there is nothing to stop us creating imagefiles, i.e. virtual floppies, on the PC side, I also would have a battery backup, so AUXRAM contents remains when the TEK is powered down.
 
Jos,

Ok - I just thought that would make the system standalone.

Your approach with battery backup on the SRAM will do that too. You will only need a PC to put in a different image.

How long do you think the battery will keep the SRAM contents valid?

Monty
 
nikola-wan said:
Jos,

How long do you think the battery will keep the SRAM contents valid?

Monty
Click to expand...

Between 2-5 years.. ( Ram retention mode leakage at around 10 uA, CR2032 capacity 200 mAh ) There is quite some difference between old 4116's and moderm SRAMs !

Would you prefer an SD card option, at the price of an all-SMD design, i.e. more dificult to build ?
 
jdreesen said:
Between 2-5 years.. ( Ram retention mode leakage at around 10 uA, CR2032 capacity 200 mAh ) There is quite some difference between old 4116's and moderm SRAMs !

Would you prefer an SD card option, at the price of an all-SMD design, i.e. more dificult to build ?
Click to expand...

Jos,

That's a very long retention time.

I think your USB concept would be fine - most of us (including me) would likely have a favorite image. Loading a new image from a PC with USB would be fine to demo other programs.

You can count me in on wanting two of them, one for my 4052, one for my 4054A.

Monty
 
nikola-wan said:
Did you get serial working on your 4052?
Click to expand...

Hi Monty,

Not yet because I'm a bit too busy at the moment making some space here. Clearing out a lot of stuff which is not my core collection. There is about 450 kilogram of old computer iron waiting for me to pick up... So clearing out will keep me busy for a while ;) That is why the Tek has to wait a bit longer...

Regards, Roland
 
Finally...., finally... it (sort of) works.

Took me forever to realize that Transera managed to put both the RTC and the AUXMEM dataport on the exact same address ( 0xFF58 ).....hence datacorruption.

If I disable the RTC ( by way of another PAL setting in the MFM), then the AUXMEM works as it should. Normally it would be less of a problem, but in my setup the firmware that controls the AUXMEM sits inside the MFM module, i.e. the other slot, thus both slots should be active at the same time.
No easy way out here for me... either put the firmware on the AUXMEM board (have to make new boards, component density becomes a problem..) or have to run a wire between both cartridges, a very ugly solution.

And I still have to do the USB programming..

As a beside : the AUXMEM board, with a EPROM instead of the SRAM, and without the USB stuff, would be a simple program cartridge. This calls for a "gaming cartridge" !
 
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Jos,

Would it be easier to change the IO address in one of the ROMs so the RTC and AUXMEM have different IO addresses?

Monty
 
I thought about that but rejected it at first because I did not have a good 4052 assembler / disassembler. But since all other options were even worse I did just that : the AUXRAM ports now live at 0xFF7x instead of 0xFF5x, the GALs in both the MFM and AUXRAM module have been changed such that the AUXRAM port is always active, even when the MFM ( i.e. the other cartride) is selected.

And : Success ! I can now save and restore files / programs on the memory module, and MFM / RTC functionality is still there !
tekauxmem.jpg

So now I need to check if batterybackup is working, and create the USB download/upload functionality.
 
Outstanding progress!

I believe Dave has a 4052 disassembler, but he has not been working on Tektronix for some time now.

Otherwise, the 4052 assembler documentation has the info I think would be needed to create a disassembler using a disassembler that has custom CPU support.
 
So, while functional, the first version of the PCB had too many issues to leave it at that. So an updated design was made & tested. This time I am satisfied with the outcome, a small routing error notwithstanding.
The resulting AMM ( = auxilliary memory module)
AMM_top.jpg

This unit is functionality identical to a Transera Auxilliary Memory unit fitted with a 512K memory box. Read that manual for a description of the file system implemented in this unit
Memory is conserved during powerdown with a CR2032. Additionally an USB interface is provided which will save & restore the whole 512K to a PC running Linux or Win10. This takes just a couple of seconds.
I am currently expanding the PC-based software such that it can deal with individual files & not just 512K imagefiles.

USB operation is not in any way synced to the TEK and must be triggered from the host PC.

The unit can be read/written by the PC outside the TEK, or while inserted in the TEK expansion slot. Likewise an USB connection is not required when using the AMM inside the TEK. ( i.e. it is possible to load an AMM cartridge at a PC, then insert it into a TEK for usage.)

You do need my MFM module with an adapted Transera firmware inside, in the other slot of the TEK4052/4. Not enough place left to also include the firmware...

I'll await Monty's verdict on this development before offering it to others !


And sorry again for the 4051 owners : the Transera firmware is strictly 4052/4 only...
 
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