Stuart

With the PAL consoles, the console outputs R-Y, B-Y and Y to an external modulator box which generates the single RF video signal.

As far as I can see, it's not necessary to save the registers at all, as there is no code that overwrites them.

The TI Extended BASIC loader doesn't support the REF external references. See E/A manual section 24.4.4. What you need to do is set up EQUates for the external references - the addresses you need are in section 24.4.8.

http://www.stuartconner.me.uk/ti/ti.htm#power_supply_consumption

The joystick is mechanically connected to a pair of variable resistors in the base of the joystick. Moving the joystick in the X and Y directions varies the two resistances. Apply a voltage across the resistors and this gives a pair of varying voltages which are proportional to the joystick position. Convert the analogue voltages to digital (through an analogue-to-digital converter IC) then you can do things with them in software. So with the joystick at one extreme X position might give you a reading of 0, and this increases steadily to 255 as you move the joystick to the opposite X position. Take a look at http://www.stuartconner.me.uk/tm990/tm990.htm#etch-a-sketch which is an Etch-a-Sketch program using two rotary knobs rather than the pair of variable resistors in a joystick. If the UberGROM has two ADC channels then this could easily be ported to the 4A.

Jim, take a look at the diagram below, which shows the wiring required from the serial port on a TM990 board to a PC serial port. On the TM990 side, it shows the connections from the TM990 serial port connector to the TMS9902 (RS-232 level shifters/transceiver omitted). Not sure whether the port on the TI-99/4A has the same pinout or not. Stuart.

With XB, you could use CALL LOAD and CALL PEEK to loop through the 32K and check it.

Comparing how the CRU works at software and hardware level: Load R12 with the CRU base address (such as >1F00). This is the address presented on the address bus A0 - A15 for CRU operations. A0 - A2 are always 0, and A15 is ignored. Your CRU hardware address decoding needs to work with the address in R12. With the (assembly) TB, SBO and SBZ instructions, you specify a signed offset. At the hardware level, this offset is shifted left one place, hence doubling it, and added to the CRU base address in R12, and that value is presented on the address bus. As your CRU device is not connected to A15, but to A14 up to A10 (or whatever), the device is also in effect 'shifted left one place' and sees the original offset specified in the CRU instruction. So the CRU device documentation talks about the functions of CRU bits 0, 1, 2, ... (counting by 1's), which match the offset you specify in the CRU instructions.

I've got it disassembled somewhere, so if you haven't got it on disk, it shouldn't take too much effort to make a cartridge out of it to use the 32K RAM,

Looks like a polystyrene type to me. https://www.google.co.uk/search?q=capacitor+polystyrene&source=lnms&tbm=isch&sa=X&ved=0ahUKEwihxa_cvZfRAhWIrxoKHcUEB5MQ_AUICSgC&biw=1215&bih=965 The marking "302G" is I believe 3000pF +/-2%.

Hi Jim, Someone from the UK was interested but hasn't yet responded to an e-mail from the owner. The owner and I will chase him up. If he has changed his mind then I'll try to pick it up from him for shipping to the US - with RickyDean's message below, two people in the US are now interested. Was the Cortex that you got from the UK sent separately or with the Marinchip system? If separately, do you recall (a) approx. how much the shipping cost, (b) who it was shipped with, and © what sort of packing was used (wooden crate, cardboard, ...?)? Stuart.

There are various messages on MSX forums (which also use the PAL TMS9929A) that you can get a picture from the VDP using the components inputs on a TV but the colour levels are all messed up, and you'll need some electronics to restore the colour levels to something usable.

Be aware ... I seem to recall that the Lantronix installer only scans addresses 192.168.1.x. If you've got your network set up as 192.168.0.x then the Lantranix installer won't find the device. There are various freeware programs around such as http://www.advanced-ip-scanner.com/ that might be useful to find the UDS-10.

Soldering classes - here's someone doing the test at the end of day 1.

I think Vorticon has got that bit sussed out already otherwise the PSU wouldn't be working at all.

I don't think an AT supply is "unregulated". As far as I know they work in pretty much the same way, but the form factor (size) and connectors are different.

Apparently the +/-12V outputs of a PC switched mode supply normally only approach +/-12V when under a reasonable load. With no load then they'll be less than +/-12V as you have seen. One solution apparently is to wire in a car brake light or two to give a bit of load, or a couple of high power resistors on heatsinks.

I've been approached by someone in the UK who has a Powertran Cortex they want to get rid of. It hasn't been used for 30 years. They don't want any money for it, but are keen that it goes to someone who will get some use/enjoyment out of it. I understand that it's a kit-built version with the disk interface added, and is in reasonable condition. He can't get it to work with a modern TV - which might mean it's not working, or the TV just can't sync to the video output. If it's not working, it should be repairable - all the ICs used are still available. Is anyone in the UK interested? It will need to be picked up from the owner in Birmingham on a date to be agreed, but NOT over the Christmas period. If no one in the UK wants it, I'll consider picking it up myself (it's at least a half-day round trip) and packaging it for shipping (which will be quite expensive - it's heavy, and I'd like a contribution to my petrol costs!) PM me if interested. Stuart.

Some more TM990 modules on eBay for a good price: Another CPU module: http://www.ebay.co.uk/itm/132022103829?ul_noapp=true 32K Dynamic RAM module: http://www.ebay.co.uk/itm/142199109600?ul_noapp=true Industrial comms module using a TMS9980 and TMS9903: http://www.ebay.co.uk/itm/142199109600?ul_noapp=true The seller has lots of other TM990 modules listed, if Jim fancies assembling his own wafer fab in his basement, right under his wife's nose ... Stuart.

If you decode the bus status lines you can increase the memory used above 64KB. The bus status lines enable you to differentiate between accessing an instruction and accessing various types of data, and you can direct each of these operations to separate 64K memory banks. So you could have for example 64K of instructions and 64K of data. You could go even further and have all your source and destination operands in one bank, immediate operands in another, and workspaces in yet another. Would be "interesting" to program such a system!

I'll send you some info by e-mail.

Try contacting the seller directly through eBay. In the past he's been quite amenable to selling to people directly.

There's a TM990 processor card (which you can play with standalone) on eBay at the moment for a very reasonable starting bid of $49.95. No bids yet - I suspect it will go unsold unless someone on here nabs it. This card appears to be made by Varian and is a copy of the TI card. Varian was one of TI's big customers for these cards. It includes a clock chip - which I believe also cores and blends apples. The card appears to incorporate a couple of mods made to the TI card (a couple of tracks cut and a pair of wires added) to tweak the memory map to support the clock chip. http://www.ebay.com/itm/VARIAN-PREDISPOSITION-IMPLANT-IMPLANTER-PREDAP-CPU-E-15002170-TI-TMS9900JDL-CPU-/132009625601?hash=item1ebc630801:g:bQEAAOSwj85YMksU

I added a clock to a Speech Synthesiser yesterday evening. It's actually pretty easy to do, and you can access it from anywhere. I'll put it on eBay if anyone is interested. http://www.stuartconner.me.uk/ti/Speech_Synth_Clock.jpg

Yes, the Baud rate, parity and stop bit were changed (for compatibility with the settings used for TIXMT (if I remember correctly). From my web page http://www.stuartconner.me.uk/ti/ti.htm#internet_web_browser: The Lantronix UDS-10 will need this configuration for Channel 1: NOTE: The configuration has been changed from that used for browser v9 and earlier. Note the different Baudrate and I/F Mode settings. Baudrate: 38400 I/F Mode: 4C (8 bit, no parity, 1 stop bit)