Stuart

Sounds like my http://www.stuartconner.me.uk/ti/ti.htm#minimem_lbla_tibug_disassembler_cartridge might be what you're after?

Video problem is stuck bit 2 in the video RAM. https://www.ninerpedia.org/wiki/Troubleshooting shows you which IC to replace.

I've got a console with those caps as well, so possibly the factory did go through a phase of fitting them?

There are 9901's specced to run at 4 MHz - look for the "-40" suffix in the part number, i.e. TMS9901NL-40. BUT as the clock input is (presumably) also used for synchronising/timing the CRU signals, is using a different clock frequency to the processor really going to work?

If you need more I/O pins than are available ... in my first TI console I had many years ago, I piggy-backed a second 9901 on top of the first one (with the I/O pins bent out obviously), and picked off a /CS signal from somewhere for the unused >0800 CRU address range. Unused logic gates are likely to have their inputs tied either high or low, and you'd need to do some pin or track cutting to 'free' them. Personally I piggy-back any extra TTL ICs I need on top of those already fitted, just picking off the two power pins.

That's right - at the moment the sensor output is mapped to just 15 notes - I was going to try to play a Christmas carol, but difficult to repeatedly position a hand to play a certain note.

You can get adaptors to convert between sizes, such as https://www.quietpc.com/x-fan-adaptor.

A little project I've been working on - to produce a simple TI-99/4A theremin. Implemented using a pair of analogue distance sensors (one for frequency, one for volume) connected to a multi-channel I2C analogue-to-digital converter, which is interfaced by bit-banging the joystick port. A bit tricky to play any sort of recognisable tune at the moment as (1) the sensor outputs could do with a bit of smoothing and (2) I haven't got a musical bone in my body. https://youtu.be/95P-vL_4Hbc

Tricky to get PAL composite video I think as none of the VDPs directly output a PAL composite signal - you've always got to mix the VDP outputs to make a composite signal. (Unlike the TMS9918 which outputs an NTSC composite signal). Wondering if there's room to mount the RF modulator PCB (with the big ASTEC modulator box removed if necessary) directly in the console (sticky pads and insulation on the motherboard shielding) and pick the composite signal off of that?

They're not resistors - they're just strips for distributing power to different parts of the PCB. Use a multimeter to work out which pins are connected to which (there are probably at least two metal strips within the package, with some pins connected to each strip. Then double check it. Then triple check it. Then connect the equivalent pads on the PCB using some decent gauge wire. If you get the connections wrong, you'll blow some chips ... Or alternatively solder a short length of wire through each hole in the PCB and solder the other end to the stump of the pin on the white strip. Just be careful that nothing can short out when you refit the PCB into the metal shell. And stop bending them!

The bodger in me wants to suggest reassembling it in the case with a bit of folded cardboard positioned just where you need to apply pressure ...

Is the clock chip socketed? Presumably that's a heatsink with white goo in the video? If socketed, pop it out, clean pins and replace. Does moving any of the wires (particularly the ones from the PSU) have the same effect as pressing on the PCB? The VDP is also socketed - probably worth removing and cleaning pins just to be sure.

Values best established by experimentation I think. Probably best to make sure interrupts are off as well, just in case.

The contacts on the DIN connector on the motherboard sometimes come lose with the plugging/unplugging of the modulator. Try resoldering the connections to that connector.

Tiny little typo in the listing: LI R4,BAUDTB=2 should be LI R4,BAUDTB-2 (minus 2, not equals 2) Note that the values in the Baud rate table are for no-wait state memory. The values in the first column will need recalculating if the code is run from memory with wait states. The Baud rates, from the top to the bottom of the table, are 19200, 9600, 4800, 2400, 1200, 600, 300, 110 Baud.

There's some sort of 'thing' where people upload blank listings to eBay then revise them later. Purchase price and postage are initially high as it is free to reduce them when revising the listing, but costs money to increase them (IIRC). The fact that the picture is a TI keyboard is just a coincidence. As to why they do it, no idea ...

Correct - as per the CF7 documentation.

Register 1 bit 1 as message above … but you can't set that directly using a CALL LOAD. You'll need to write and load a small assembly program to set the register bit, and call that program through a CALL LOAD. (Although I now wonder if you can use CALL LOAD to set the screen timeout counter to blank the screen?)

Hi Michael. No worries ... I've just tried out the suggestion from Lee above (thanks Lee!) of using Asm994a to write directly to a disk image, then I've used TIMT to extract the TIFILES file image from the disk, and that works fine. So I'm all good to go again!

According to the datasheet, the Lattice 22V10 GALs support open collector (open drain) outputs, but you might need a logic synthesis tool (rather than 'just' a GAL compiler) to support it.

Hi Michael, I've attached a (slightly later version of) the object file I tried importing onto the disk. This was generated by Asm994a running under Windows, and it has >0D >0A bytes at the end of every 80-byte record. zTIPI.obj

It's a problem copying a particular TIFILES format EA3 file from PC to TIPI - there's some sort of corruption going on. Omega will raise it direct with Matt.

I was rather hoping you were going to fix the import bug in TIMT as I'll have a succession of file images to import. Is that a possibility? (No great rush, looks like there might be a PC-->TIPI transfer bug that needs sorting out as well.)

Hi Michael, I downloaded the TIImageTool this evening and had a play. Lovely user interface! So I created a new disk, then Edit > Import Files and imported the Asm994a object file as type Dis/Fix 80. Viewed the file in the tool and it all looks OK. Right-clicked the file and selected Save As TIFILES, and saved the file. But if I try to load the file in Classic99 E/A option 3 I get an illegal tag error (just testing the file in Classic99 as if it works on there it seems to work on Omega's TIPI). Any idea of the problem? I've attached a zip file containing the disk image and exported TIFILES file. TIFILES.zip

OK, so back to this question again. I've got an E/A object file (uncompressed) on my PC from Asm994a and I need to convert it to TIFILES format so it can be loaded through a TIPI, and it's now too big to load in the E/A editor in Classic99 and save back out. How else can I convert it? I expect Ti99Dir will do it but can someone confirm exactly which menu option and dialog options I need please? Thanks all!