TI SD card

[Madhatter1]

This is similar  to a CF7, but use SD card and has nothing to do with CF7.

It allows a TI-99/4a to use disk image volumes on SD card as floppies.

I started this a couple years ago and have decided to share it in case someone else wants to build one.

 

https://github.com/dennishatton/TI-99-4a_SD_Disk_Project

[Shift838]

nice.  i may have to order a few PCBs from my supplier during my next round.

 

if anyone want's to get on board with a PCB shoot me an email.

[AtariNostalgia]

What's the estimated price on these?

[Shift838]

 

3 hours ago, Madhatter1 said:

This is similar  to a CF7, but use SD card and has nothing to do with CF7.

It allows a TI-99/4a to use disk image volumes on SD card as floppies.

I started this a couple years ago and have decided to share it in case someone else wants to build one.

 

https://github.com/dennishatton/TI-99-4a_SD_Disk_Project

Very cool project.  I checked out the Kicad project and there does not seem to be a created PCB file (just a blank one).  Did you ever get one tooled or have gerbers for the is project already?

[Madhatter1]

1 hour ago, Shift838 said:

 

Very cool project.  I checked out the Kicad project and there does not seem to be a created PCB file (just a blank one).  Did you ever get one tooled or have gerbers for the is project already?

There is no PCB and I don't intend to make one.

I built this using wire wrap for myself.

I never know when I will make a change.

 

If someone wants a PCB, They can use KICAD to make one.

I wished I would have used Eagle, Because Eagle is now part of Fusion 360.

In which case I could have milled a PCB on my CNC.

 

This ATMEGA162 emulates the disk controller and interfaces to the TI DSR rom.

 

[fabrice montupet]

I like your project and I think that I will make make one , thank you 🙂

[Shift838]

53 minutes ago, fabrice montupet said:

I like your project and I think that I will make make one , thank you 🙂

i think i will use the schematic to port it over to eagle then.

 

 

[RickyDean]

I've got two Bunyan and two Fetzer protoboards. I may take one and do this and the Nouspikel USB, both of them, on it, for the peb box.

[+FarmerPotato]

On 2/11/2021 at 4:05 PM, Madhatter1 said:

There is no PCB and I don't intend to make one.

I built this using wire wrap for myself.

I never know when I will make a change.

 

If someone wants a PCB, They can use KICAD to make one.

I wished I would have used Eagle, Because Eagle is now part of Fusion 360.

In which case I could have milled a PCB on my CNC.

 

This ATMEGA162 emulates the disk controller and interfaces to the TI DSR rom.

 

Nice! I use wire wrap too

 

So this acts like a drive attached to the TI controller? Or do you mean it has its own DSR ROM replaces the need for a controller?

 

 

 

[Madhatter1]

15 hours ago, FarmerPotato said:

Nice! I use wire wrap too

 

So this acts like a drive attached to the TI controller? Or do you mean it has its own DSR ROM replaces the need for a controller?

 

 

It uses the TI DSR rom. I wanted it that way so it would be total compatible.

 

 

[Madhatter1]

8 hours ago, Madhatter1 said:

 

I miss read your question.

It is complete, you do not need a TI disk controller.

[+arcadeshopper]

I'm going to try and build a PCB for this that will plug in to the sidecar memory card/TIPI 44 pin stack

 

Greg

[jrhodes]

2 hours ago, arcadeshopper said:

I'm going to try and build a PCB for this that will plug in to the sidecar memory card/TIPI 44 pin stack

 

Greg

Awesome. Love my tipi, but this thing is going to be interesting to mess with.

Already got a nonopeb on my spare ti, but i may just replace it with one of these if it lives up to expectations.

Edited March 4 by jrhodes

[Vorticon]

Does it require an external power supply or is it powered directly by the TI?

[Madhatter1]

I powered it from the TI bus

[Madhatter1]

I'll correct the D6 & D7 mistake and flag the unused inputs, Thank you.

I built this using wire wrap and never intended to make a PCB.

It is working. I have been using it for a couple years.

You can find a SD module on ebay for a couple dollars.

It will take care of the 3v logic to 5v TTL.

BOM is what you see n the schematic.

I did make change from ATmega8515 to ATmega162.

The 162 has more ram allowing me to read a full 512 byte sector from SD card.

With ATmega8515 I original was only using 256 bytes of sector and would have to double the disk image file.

That allows me to directly copy and modify disk image on PC.

[Madhatter1]

I have cleaned up the ERC errors and uploaded new schematic

[Madhatter1]

I just realized there are no decoupling capacitors in the schematic.

Since I added them in as was wiring the power bus.

 

You could just solder them directly across the power pins of the ICs

Or If someone wants to add them to schematic before making a PCB.

[Shift838]

On 3/8/2021 at 11:35 PM, Madhatter1 said:

I just realized there are no decoupling capacitors in the schematic.

Since I added them in as was wiring the power bus.

 

You could just solder them directly across the power pins of the ICs

Or If someone wants to add them to schematic before making a PCB.

A few questions.

 

1. Looks like the 2N3904 has the same symbol but has the pin #'s in different locations.  Locations do not look mirrored, so I'm wondering why and if we follow the schematic symbol for the wiring or the actual parts pin #'s on the schematic

 

See attached pic.  I believe the one on the right is correct as it has the standard layout, but the other 2N3904 the pin #'s do not match the standard layout.

 

 

 

Edited April 21 by Shift838

[atrax27407]

The TI Disk Controller DSR is burned into two (2) TMS2532s.

[Shift838]

15 minutes ago, atrax27407 said:

The TI Disk Controller DSR is burned into two (2) TMS2532s.

yes on the original TIFDC it does.  It looks like @Madhatter1used a 2764 to be able to fit both 2532 code into one 2764.

Edited April 20 by Shift838

[Madhatter1]

The one on the right is correct EBC.

I'll correct the schematic.

[oddemann]

New to all this "make it yourself!"

I have no clue how to open up the PCB file. The tools for Windows, I kinda get, but I need to make a PCB and then put all the parts on. But... what software should I use to open up all of this? So I have time to understand all the stuff, but I need to start with the PCB and order that with the parts. And then I can tackle the stuff to make an image and all that.

[Shift838]

9 hours ago, oddemann said:

New to all this "make it yourself!"

I have no clue how to open up the PCB file. The tools for Windows, I kinda get, but I need to make a PCB and then put all the parts on. But... what software should I use to open up all of this? So I have time to understand all the stuff, but I need to start with the PCB and order that with the parts. And then I can tackle the stuff to make an image and all that.

I have used a few different  PCB design software packages.  Eagle and Kicad are both good options.   I lean myself more to Eagle as it is now integrated with Fusion 360.  

 

 

[oddemann]

3 hours ago, Shift838 said:

I have used a few different  PCB design software packages.  Eagle and Kicad are both good options.   I lean myself more to Eagle as it is now integrated with Fusion 360.  

 

 

EAGLE is now only available with a Fusion 360 subscription. - To bad! But thx for the tips!