jens-eike

The important part about our original TI power supply is the -5V rail: the 4116 VDP RAM chips require -5V to be present BEFORE the other voltages (see 4116 data sheet). The transformer's 16V rail supplies input to the positive voltages (+5 and +12), while the 8VAC is regulated to -5V and never swithed off to fulfill this requirement. I am not sure if any generic PSU can do that.... The newer two-wire power supply probably has some built-in sequencing to apply voltages in the right order (smaller caps for a faster rise of -5V before the positives or something similar?).

IF you only have two wires from the above plug (red and white only, as with the later switching supply boards) THEN an universal supply as used for modern laptops might work. The two-wire supply works from about 19V DC (or a little less AC, so the standard 16VAC power bricks are ok). If you are in continental Europe, I have spare original power suplies with the appropriate plugs (as used in Austria, Germany or Denmark), too.

There is no such thing as PAL or NTSC cartridges for the TI-99/4A!!! One ebay-seller tries to sell carts as "NTSC-only", but he is probably influenced by japanese video games - Nintendo or Sony have some system dependant games, but this is more a licensing issue, as the region codes on DVDs. I have tried playing Alpiner in parallel on a PAL and NTSC console at the 2006 Treff, the music played 20% faster on the NTSC console due to more frequent VDP interrupts.

Easy: connect a switch between pin 6 and ground. Closing the switch will disable the '138 decoder.

My /8 has the card edge connector. Which Armadillo Interface do I need, the "flat cable" or "round cable" type? Are there other variables than the different pin-out of card-edge versus Centronics connectors? The interface card itself should be the same in both cases? Is your 128k RAM card 99/8 compatible and can it be adjusted to different mapper areas? How many projects are you working on - with all these cards and banked-ROM and Über-GROM cartridge boards now? I am interested in: 5 prototype boards 1 Armadillo interface 2 128k RAM cards Next project idea: a large RAM card for the 99/8 to fully exploit the 16M address space....

Here are some scans from TI-Revue (HCA) 10/1987 showing a simple RAM expansion using only one 62256 and two TTL chips. The 74HCT08 is a better choice than my idea with diodes to combine select signals (same trick saved a Horizon RAM disk for me from flaky operation).

Use one 62256 RAM and combine the select signals via (schottky) diodes plus a pull-up resistor - that saves 3 large chips (or stacking). The '138 + diodes could be replaced by a 74LS156...

I'll take a few, too! :-) (and if you have any 99/8 specific boards left...)

5.25" disks are about the same size as CDs, so how about this: https://de.hama.com/00078379/hama-cd-rom-alu-file-box-160-silver https://de.hama.com/00078359/hama-cd-rom-aluminium-file-box-300-silver quite expensive, but look alot better than the 30+ years old plastic boxes in my basement. If I can find these locally, I'll give it a try.

That is my approach, too. But with an adapter board and the RAM chip ( I have the M48T08 ), yo will lose the adjacent slot in the PEB...

There is a TI Sudoku here: http://www.errorfree.de/Menu08.html The page is in German, but the game supports 5 languages (I suppose English is one of them...).

It is a little more complicated than just changing a jumper: http://www.mainbyte.com/ti99/rs232/rs232.html

My 3.5" is an EPSON SMD-120. Datasheet: http://www.sharpmz.org/download/floppy_smd100_specifications.pdf

1. Yes, some TI-users had 40-track 3.5" drives (Epson), they were especially popular in the Wiesbaden group. 2. Yes, there were several mods to disk controllers, [url=http://www.mainbyte.com/ti99/store/EPROMS.html lists EPROM upgrades for the TI and Myarc FDC. You already know about the Geneve using 1.44MB floppies. Btw, does it matter if your image has 1440 sectors as DS/DD40 or DS/SD80 (TI controller modded) or even SS/DD80 as long as the controller manages to find the correct sectors?

On Fred's webpage, the function is documented as "TIME": (Why don't you get an error for opening "CLOCK"?) HDX1.TIME If a data file HDX1.TIME is opened in INPUT, OUTPUT, APPEND or UPDATE mode then it is possible to read the PC's time. The file characteristics for the HDX1.TIME file is INTERNAL, FIXED 32. Data written to the HDX1.TIME file is ignored (for now). Read example: 100 OPEN #1:"HDX1.TIME",INTERNAL,FIXED 110 INPUT #1:SEC$,MIN$,HOUR$,DAY$,MONTH$,YEAR$,DAYOFWEEK$ 120 CLOSE #1 Write example: 100 OPEN #1:"IDE.TIME",INTERNAL,FIXED 110 PRINT #1:SEC$,MIN$,HOUR$,DAY$,MONTH$,YEAR$ 120 CLOSE #1 Hours from 00 through 23, minutes and seconds from 00 through 59. The day of the week from 01 to 07 (01=Sunday). The month 01 through 12, day of the month 01 through 31 and the year 2000 through doomsday (which apparently is around the year 9999!)

Doesn't VWTR transfers the data byte then the register# OR >80 ? In http://www.konamiman.com/msx/msx2th/th-4b.txt the "data to be transferred" is always written to R44

Looks good, -3 is a 200ns part. Datasheet: http://pdf.datasheetarchive.com/datasheetsmain/Databooks-2/Book273-441.pdf Check the individual timing requirements with the 9918 Data Manual (with only 10ns to spare, there might be tiny differences between the TMS and MK parts).

Google's 2nd hit for "itt 4116 datasheet" gives a link to datasheetarchive.com - there is only a list of itt chips, but it says -4 is 250ns ( -3 is 200ns, -2 is 150ns) NS is probably some package code, for TI chips "NL" means plastic (N) and 0-70°C (L). How about: http://www.ebay.com/itm/Vintage-TMS4116-15NL-TI-1981-16-PIN-DIP-4116N-/370541819544?pt=LH_DefaultDomain_0&hash=item5646037698 (this seller has several makes/speeds of 4116).

You should look at the speed rating, my 99/4A boards have 150ns chips (TMS4116-15 or MK4116-2), the chips you found on ebay are itt4116-4 rated for 250ns access time - definitely too slow for the VDP! According to the 9918 Data Manual, appendix B, 150ns or 200ns will work, 250ns chips are too slow.

I tried a 74LS175 for bank selection, it has a -RESET input to start at bank 0, and it allows for true (write >0 for bank 0)or inverted ('379 style, write >F for bank 0) output. Drawback: you need an extra 74LS32 (or a strange construction with two diodes and a pull-down resistor) to combine -CS and -WE to clock the register. If you need more banks, the 74LS174 stores 6 bits, but has only true outputs

no existing ROM chip is too slow for the 8-to-16-bit converter logic (check Thierry's site!) http://nouspikel.group.shef.ac.uk/ti99/wait.htm 8-bit ROM is just as fast as 8-bit RAM

Driving to Eindhoven now :-)

How about using different keys for (P)ause and (C )ontinue? This adds a compare, but avoids timers and counters (and comparing their results in turn).

Looks like the 4164 RAMs are missing (and probably a few 74LSxx chips).

Try Thierry's site: http://nouspikel.group.shef.ac.uk/ti99/tim9904.htm describes the Reset circuit. Your momentary contact should short the 150k resistor.