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

[nikola-wan]

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:

[nikola-wan]

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

[jdreesen]

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

[Roland Huisman]

Hi Jos, that would be very nice!

[jdreesen]

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...

[nikola-wan]

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.



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

[jdreesen]

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.

[nikola-wan]

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

[jdreesen]

Jos,

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

Monty

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 ?

[nikola-wan]

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 ?

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