The F18a DIY alternative with HDMI :)

[retrocanada76]

On 12/5/2023 at 8:37 PM, RickyDean said:

Well, I just moved my Genny into the Den and pulled my TI stuff out of the box. I then proceeded to hookup the Tang unit and a USB-C cord to power it as it does not power from the HDMI or the V9938 socket. I then hooked up my HFDC and placed the boot disk HFE into my  HXC floppy emulator and powered up. I get a corrupted screen where the Swan should be. But after some seconds the floppy drive is activated then it activates it again and after some moments I get the Enter Time screen for Geneve OS. I don't have a keyboard hooked up, so cannot go further at the moment. Did take a video, but it's 181MB in size so can't upload it. But the main thing is, it works.

 

Just uploaded the video to youtube, here is the link  

 

ok, It seems to be working. Did you connect the A1 line ? 

[retrocanada76]

I have no idea how a normal boot would be I don't know this kind of computer but for the tang to display something means it has set R1 BL field to 1. So it initialized it.

 

Now it might be partially initializing it and this is the reason you are seeing garbage. I don't know what are the default values for a real TMS9918 for the R0-R7 registers. These are set in the vdp_register.vhd module. You can look at the default values then RESET line is active

[retrocanada76]

But you really need A1 line to be connected or you may write garbage to it. You need to pull this line somewhere else in the computer as the TMS socket does not get it

 

[RickyDean]

7 hours ago, retrocanada76 said:

But you really need A1 line to be connected or you may write garbage to it. You need to pull this line somewhere else in the computer as the TMS socket does not get it

 

Okay, I'll look into it, let you know the results.

[RickyDean]

17 hours ago, retrocanada76 said:

But you really need A1 line to be connected or you may write garbage to it. You need to pull this line somewhere else in the computer as the TMS socket does not get it

 

@retrocanada76

Okay, I have a question. You are saying to connect the A1 line. The TI address and data lines are reversed from that of most systems. Meaning D0 would correspond to D7 on a standard IC, A0 would correspond to A16 on a 16 bit IC, A1 on another IC would correspond to A15 on the TI/Geneve, as the address lines always start at  A0 and go up to A15. Does this means that your A1 would correspond to A15 on the Geneve/TI bus? If so, would I pull a line from A15 to whichever line on the Tang 20k would be considered A1?

Edited December 31, 2023 by RickyDean

[Artoj]

I am not sure where the A1 line is either, I think retrocanada76 might means A1 line on the Tang? With the TI99 the A0,A1,A2 are used for encoding CSW CSR on the TMS VDP chip. Ricky is right A1 is A14  on the TI99 and it is connected to pin 13 on the TMS VDP chip (mode). Regards Arto. 

 

[RickyDean]

This would be using the Tang 20k with a Geneve, using your V3 board and 64 pin vdp board, if that makes a difference? Also is it possible to change the memory from 128k on the v9938/58 program to 192k, which is supposed to be the max the v9938/58 can address? Where would the memory function in the program reside, maybe I can tweak it? I haven't changed it to act as a v9938, as of yet, I haven't found that option yet, so it is still functioning as a v9958 vdp.

Edited December 31, 2023 by RickyDean
added content

[retrocanada76]

The tang20k socket (which is the same for tang9k 9958) has a A1 pin on it. You need to pull a jumper for the address bus A1 because the 9958 has 4 register ports (on MSX2+ they are x98, x99, x9a, x9b)

[retrocanada76]

i'm talking about the small board that you plug into the TMS socket. Just look at it.

 

[RickyDean]

@retrocanada76, I Have attached the schematics and pinout for the tang 20k here, I have looked them over and cannot find a A1 pin listed on the tang. I have also looked over the PCB's on the v3 board and the socket board for the v9958 and there are no letters or numbers on the pinouts. I see on the schematics for the v9958 socket that pin 50 which listed as AD1, and which corresponds to  AD1 on the v9938/58 vdp. If this is A1, then it would correspond to A15 on the TI/Geneve address bus, due to the Big Endian numbering I mentioned earlier. So do I pull a wire from here and then where do I need to connect it to on the Tang assembly, as there is no callout for an A1 on the Tang? Or do I connect it to one of the 74lvs245 A1 pins? Thanks for any assistance

Tang_Nano_20K_3921_Schematics.pdf

[retrocanada76]

it's called MODE1 because it goes to MODE1 on the 9958 but it is in reality the A1 line.

 

[RickyDean]

10 hours ago, retrocanada76 said:

it's called MODE1 because it goes to MODE1 on the 9958 but it is in reality the A1 line.

 

Mode1 pin connects to the J3 connector, where does this connect on the v3 fat board? Does it not already connect through the ribbon cable to the Tang 20k? After tracking the v3 20 pin connector and looking the V3 traces on the PCB  view and Gerber, it appears that the mode1 goes to pin 7 of the left most 74lv245. Does it need further connecting to the tang?

Edited January 5 by RickyDean
additional content

[RickyDean]

12 hours ago, retrocanada76 said:

it's called MODE1 because it goes to MODE1 on the 9958 but it is in reality the A1 line.

 

Or are you saying that I need to connect mode1 (A1) to the A15 line on the Geneve?

[retrocanada76]

You need to connect MODE1 (from the socket) to A1

 

[retrocanada76]

the signal goes further down to tang where is serves as MODE1 together MODE0 they make the 4 registers

 

[RickyDean]

2 hours ago, retrocanada76 said:

You need to connect MODE1 (from the socket) to A1

 

Okay, So do I tie into A1 at the 74LVS245 or do I tie into A1 on the Geneve bus? Here is a pinout of the Gate Array on the Geneve. It has A0-A15 on it

[retrocanada76]

get this pin 80 (A1) and connect it to the MODE1 i showed you. Don't bypass anything the pin is there to be easily connected / disconnected.\

 

[retrocanada76]

[RickyDean]

4 hours ago, retrocanada76 said:

Okay, thank you, I'll give it a try.

[RickyDean]

8 hours ago, retrocanada76 said:

Also I'm not using the 40 pin socket, I'm using the v9958 socket, it does not have a seperate hole for the mode1, it is already incorporated into the ribbon cable from the pin. Here is a picture of a Myarc Geneve.

Edited January 6 by RickyDean

[retrocanada76]

ah ok this computer uses 9938 instead of 9918. Right you don't need the A1 it is already in the socket. BUT, I never tried a 9938 computer there are few pin differences. I tried on a 9958 OMEGA MSX using the 9958 jumper.

 

[RickyDean]

8 hours ago, retrocanada76 said:

ah ok this computer uses 9938 instead of 9918. Right you don't need the A1 it is already in the socket. BUT, I never tried a 9938 computer there are few pin differences. I tried on a 9958 OMEGA MSX using the 9958 jumper.

 

Here is a write up about using a v9958 in a Geneve. As it stands at this moment, there are three major boot bio's for the Geneve. v.98, v1.0, and v2.0.

Using a v9938:

Using v.98, when turning the computer on, there is a picture of a Swan that shows until the system either boots off a Floppy or a Hard drive.

When using v1.0, it boots up to a selection screen, that allows you to choose the boot device from an option back in the 90's and early 2000's, basically, Floppy, mfm hard drive , Ramdisk, and Scsi hard drive.

V2.0 brings back the Swan and is supposed to give an option to choose from, the above as well as IDE drive.

 

When using the Tang 20k:

.98 starts out with a garbled screen and stays there until it boots from floppy or mfm hardrive, then it goes into the operating system.

v1.00 starts, only for a second with a garbled or black screen, then goes into a screen where it starts Loading MDOS, but it never gives the option the choose. It bypasses that screen. But it does Boot.

V2.00 starts with the same garbled screen as v.98, but it is supposed to go into another screen to give a boot choice, but it doesn't, and has the garbled screen showing, with no ability to boot at all.

 

I don't know if it's doing this because it is in v9958 mode and hasn't been modified like the pictures below show. If that could be the case, what do I need to do to make it act like a v9938 IC, to see if it works as originally described.

If that is not possible, should I attempt to modify the v9958 socket to look like the actual vdp in picture two and see if the screens boot up correctly? What do you think?

[+dhe]

That's some beautiful point to point soldering!

[+9640News]

Version 2 of the eprom does not give you a menu selection of devices to boot from. It gives the swan and then starts looking for the OS on detected devices until it finds one to load. 

[RickyDean]

2 hours ago, 9640News said:

Version 2 of the eprom does not give you a menu selection of devices to boot from. It gives the swan and then starts looking for the OS on detected devices until it finds one to load. 

Ah.. okay, I thought I read somewhere that you could choose, my bad. @retrocanada76, Maybe on the V2.0, I didn't give it enough time to cycle through the choices, I'll try again later today and I'll try it in the Geneve emulation on Mame to see how it is supposed to work.

Edited January 7 by RickyDean
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