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Hacking the nanoPEB (v1) to allow HDX functionality


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Hey guys -


Has anyone in the community looked into this yet? (Actually putting a HDX DSR on the nanoPEB)


Jamie put a copy of the TI RS232 DSR (I followed up with him to verify, and he hasn't responded yet. I don't know if it's tweaked or not.) in the NanoPEB's EPROM along with the disk DSR. I wonder how much additional modification would be needed to enable HDX functionality on one of the RS232 nanoPEB units. It would indeed be a killer combo... rather than having to remove the CF card, run TI99dir, reinsert card, etc, you can simply master/slave a PC and move stuff over to the nanoPEB CF via HDX (CF2K, DM2K, native XB/EA transfer etc.)


My first step would be to desolder the nanoPEB EPROMs and put a socket on it (and he has it stacked too) to make it easier to get at and reprogram. Possibly replace with a higher capacity one with additional address lines to compensate for the stacked EPROMs. (I haven't looked closely at the pinout yet.)



Edited by acadiel
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Got both Fred and Jamie involved now! This ought to be a fun project!


NB: The NanoPEB has a 128K SRAM on it. Only 32K is being used. We might be able to get away with using part of the SRAM pretty easily with the nanoPEB CPLD controlling the banking for the HDX RAM, and still have a switch to go from/to the HDX/RS232 DSRs.

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Yeah, the one I have resembles the bottom one, but it says "nanoPEB V1" on the EPROM. IT also has a 27C010 128K EPROM on top of the RAM chip (which is also 128K from what Jamie is telling me). I might have do some creative desoldering with mine since the chips are piggybacked.

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Adding HDX functionality directly would be awesome considering the new V1's are yet again just a little different than the last..


cf2k fails with a dsr error (*he left off SIO this time, just RS232 is in the DSR)

telco just hangs when i try it, so assume that means either telco doesn't use the DSR and the hardware is just too incompatible :(



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  • 2 months later...

The last development I have was that I got the schematic for my version of the NanoPEB from the developer... From what I can tell, we will need to do the following:


1) Replace the 32K SRAM with a 128K one to use with the HDX. Mine has a 32K SRAM; current models have a 128K, so you could easily segment a newer model.

2) Determine from Custodio's code which 8K segments are used in the EPROM and use another 8K segment for the HDX.

3) Desolder the old EPROM and reprogram it (ugh). The RAM chip is soldered with it.


It'd take a little time to prototype (unsolder, solder, run wire, etc), which unfortunately, I don't have much of right now (time). It does sound doable, though, according to the NanoPEB developer. :) Just using a different section of the SRAM chip for the HDX RAM, and a different section of the ROM for the HDX ROM. Mostly moving around wires and probably adding some pull up/down circuity and other misc stuff (probably a few wires... <grin>)

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