Stuart

Tricky I think without lots of interface logic. Remember that the 9918A is designed to use DRAM which has a multiplexed high bits/low bits address bus. You've then got to interface that to the 9900 which has a 'straight' address bus. The connections expected on the memory chips are completely different. The 9918A also has to spend time refreshing the DRAM; which would lock out access by the 9900 - not sure how much of an impact that would have though.

Check that a disk file exists for each disk that you had mounted. I've found the emulator crashes on startup if you delete or rename a disk file that you previously had mounted then start the emulator. Settings are in the Registry in HKEY_CURRENT_USER\Software\BurrSoft\Win994a\Settings if you need to see which disk files it is expecting, or to edit the settings manually. Stuart.

No performance issues, but you'll need to arrange the EPROM header to repeat in all 8 banks, rather than just 4 banks if you used a 32K EPROM for example. So slightly more work in sorting out the EPROM image to blow, perhaps.

Willsy said "Hell, for that matter, most BRITS couldn't point them out either. They're generally as dumb as fuck!" 'ere, watch it you! I know that ALL those places are north of the Watford Gap!

There's a disk copy of TI Invaders with cheat mode here, if you're desperate for some cheating. http://www.avjd51.dsl.pipex.com/ti/disk_images/Invaders.zip Load using E/A option 3. The program auto-starts on loading. Cheat mode is accessed when on the title screen by pressing <Shift>838. This prompts for a Y/N to play slow speed then two digits for the number of the screen to start on. None of these inputs will be displayed, and it is not necessary to press <ENTER>.

Excellent! Now how do we get the TI speech synth to say all that? There are a couple of words in there that sound like English: (the barbarians) "come so often" (to Barbara's bar) - is "come so often" really the same in both English and German?

If you've got 32K RAM present as well, you can use a program that I wrote - go to http://www.avjd51.dsl.pipex.com/ti/ti.htm and search the page for "CART_RAM/O". Load from disk using MiniMem option 1.

Mark asked me if it might be possible to derive coding tables for the other speech synth chips from the TI speech lab code, which supports the TMS5100, 5110, 5200 and 5220 ... In the attached zip files are two files, QV5220.COD from QBox and SPCLAB2.SRC (a text file) which is part of the speech lab software that Harald in Germany reverse engineered. Looking at the last three parameters at the end of the .COD file, these are 10298, 14979 and 19660, in hex >283A, >3A83, >4CCC. If you search for these in the .SRC file, you'll find them in the coding tables at the end of the line below the label LN6C3C. Looks like other values match up as well. So you should be able to work out how the formats of the tables in the two files are linked, and hence derive a QBox coding table for the 5200. Stuart. Coding Tables.zip

The speech synthesiser is based around a model of the human vocal tract, and much of the data is for controlling a lattice filter that shapes the sound (as an analogy, I think you'd be right if you thought about the data defining how your vocal cords are set, the shape of your mouth and the position of your tongue as you speak). If you go to my page [http://www.avjd51.dsl.pipex.com/ti_portable_speech_lab/ti_portable_speech_lab.htm#theory_of_operation] and scroll down a little to the section "A noise by any other name" (below figure 3), there is quite a good description of LPC and the coding process, plus sample LPC data for the word "Help". "The resulting LPC data is then coded to further reduce the bit-rate in accordance with the coding tables stored in ROM in the selected target speech synthesis device" - so I don't think the data you see being sent to the speech synth is actual LPC data - it's just lookup data into the coding tables embedded in the speech chip. TI during their recording sessions were able to edit the LPC data. Thierry on the other hand says on one of his web pages that he tried making simple changes to some of the speech data, but couldn't get anywhere with it. So editing raw LPC data, possible, editing the lookup data for the coding tables - looks tricky if not impossible. I was approached by some MESS guys a couple of months ago for copies of the ROMs and scans of the speech boards in my TI speech lab, as they wanted to try to reproduce the system in MESS. I gave them what they wanted, but the Speech Analysis board has a ground plane over much of both sides of the board, so there is no way to see how the components are interconnected and hence derive the circuit. [i gave them your name, Michael, as the expert on the TI/99 in MESS, not sure if they ever got in touch ...?]

Just a thought ... have you tried adding the C:\Qbox directory to the Path environment variable?

You can then use it as a "claw" hammer ...

Correct - it's a 25K file. I didn't bother padding it out to the full 32K. If you pad to 32K and duplicate, and set the jumper to 32K, I think it should work (A15 will be held high so it will use the copy of the code in the upper half of the EPROM?). You can always just erase the EPROM if it doesn't work ...

Thanks for those three boards. They're all built up and work fine. (Mark, to return the favour, do you need some 74LS379s for your boards? I bought 10, and only need three plus a spare, so the remainder are yours for the asking. Ditto for the two caps on each board as well.)

I've done a bit of work on my port of Cortex BASIC so it can now be programmed into a 32K EPROM on a 64K Guidry bank-switched cartridge, and selected from the TI main menu. When run from a cartridge, just over 14K of RAM is available for program and variable storage (compared with around 5K of RAM free when loading the program as an E/A option 3 file). Details, including a link to the EPROM binary image, are here: <http://www.avjd51.dsl.pipex.com/ti/ti.htm#programs>. If you want a little program to try out ... 10 GRAPH : XS=2: YS=2 20 A=256: B=A*A: C=192 30 FOR X=0 TO A STEP XS: S=X*X: P=SQR[b-S] 40 FOR I=-P TO P STEP 6*YS 50 R=SQR[s+I*I]/A 60 Q=(R-1)*SIN[10*R] 70 Y=INT[i/3+Q*C] 80 IF I=-P THEN M=Y: N=Y 90 IF Y>M THEN M=Y 100 IF Y<N THEN N=Y 110 IF (M=Y OR N=Y) THEN X1=X/2: Y1=100-Y/2: PLOT 128+X1,Y1: PLOT 128-X1,Y1 120 NEXT I 130 NEXT X 140 GOTO 140 Stuart.

An old disk shouldn't have affected the head alignment, but it may have made the heads dirty. You should be able to gently clean them using a long cotton bud (used for cleaning babies ears and so on) and some (pure) isopropyl alcohol. Or get a 5.25" disk cleaner from e-bay (something like <http://www.ebay.co.uk/itm/NEW-5-1-4-FLOPPY-CLEANER-AND-3-1-2-FLOPPY-DISK-DRIVE-WET-DRY-HEAD-CLEANER-/141071603708?pt=LH_DefaultDomain_0&hash=item20d885d7fc>).

379 bank-switched ROMs - it looks like the .bin file is a straight dump of the (EP)ROM - is that correct? Is there a way (in Classic99) to set which bank the 379 boots up in, to be able to test that the cartridge boots correctly from each bank? Thanks, Stuart.

Thanks Lee. I had a look around Thierry's site but somehow missed it.

Is the disassembled source available for the E/A extended utilities loaded into low memory? It's just the KSCAN and DSRLNK utilities that I'm interested in.

Thanks Mark, PM sent. Are boards from Scotland compatible with the South of England? You don't have funny electrons or anything up there?

Are all your boards spoken for, or is there a chance of acquiring one? Happy to pay the going rate plus shipping to the UK. Either a built-up board if you've already bought all the parts, or a bare board. Stuart.

Rasmus, did they produce it from the ExpressPCB format files, or Gerber?

Try putting a SBZ 0 after the CLR R12, just to make absolutely sure the 9901 is in interrupt mode rather than clock mode. Clutching at straws here!

Hmmmm ... not sure. Try inserting after your CLR R12 this little bit of code from Thierry's site which checks the <Enter> key, to confirm that at that point in your code you're able to read the INT bits on the 9901 ... CLR R1 Test column 0 LI R12,>0024 Address for column selection LDCR R1,3 Select column TB -13 Test R12-address >000A, i.e <enter> (then depending on how the bit is set, use VSBW to write either one character or another to the top left of the screen, then loop round again) So with that loop running, do you get a different character displayed when you press/release the <enter> key?

Ah, but that's reading the interrupt flag in the VDP status register. Whether that signal leaves the VDP chip and goes down the bit of wire to the 9901 is controlled by the IE bit in register 1. In other words, the fact that you can read the interrupts from the status register does not necessarily mean that those interrupts are getting to the 9901. Try loading the value >E0 into register 1 just before your bit of code, and see if it still loops forever.

Have you before that done anything with the VDP register 1? Could you have inadvertently cleared the Interrupt Enable bit in the VDP?