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hhos

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About hhos

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  • Birthday 12/23/1957

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  1. hhos

    Better cpu

    I agree. It would be better and easier to build a complete new system around the 6309. Trying to put it into the TI99/4A would be almost as bad as trying to shoe horn a TMS9900 into an 8 bit console.😀 The 6809 is fast,... very fast. If a 1 MHz 6809 running the original Defender arcade game isn't a good enough example, you should see a 1.79 MHz 6809 in a CoCo3 playing a Star Wars, episode 4 video. The hard drive containing the data it was playing was the only speed upgrade if I remember right. The 6309 is even faster than the 6809 when operated in native mode. I agree that the BASIC for the 6809/6309, in all the machines I'm familiar with, is a great deal faster, even when the CPU clock is significantly slower on the 6809 based machine. In my opinion, the difference in speed is primarily due more to the lack of CPU directly accessible RAM than anything else, and as a result of that shortcoming, the BASIC is written in GPL, which is SLOW. (Running on tracks that don't have any railroad ties?) Secondarily, I would blame excessive wait states (stop lights?), and thirdly, the register file being in RAM, right next to the read before write behavior it displays when writing byte values. TI didn't even take advantage of the 16 bit nature of the processor, or the one thing the 9900 is really GOOD at, rapidly handling 16 levels of interrupt conditions. Because the 6809 is pretty good at handling interrupts, too, I think it would probably run rings around the 9900 in most cases. The 6309, in native mode, would be even faster. It's hard to say, though, the larger register file could be a much greater advantage than I'm giving it credit for. Also, the A(dd), S(ubtract), C(ompare), MOV(e), SOC and SZC, all have a great many addressing options (they take op 3/4 of the total number of possible opcodes). That could give significant advantages to some applications by cutting down on the number of instructions needed. (Would that be bigger wheels for the train analogy above?) There really isn't any point in trying to run any BASIC benchmarks between a TI99 and any other microcomputer I can think of. Has anybody ever run any assembly language benchmarks for a 3 MHz TI99/4A vs. 0.895 MHz CoCo1/2? 1.79 MHz CoCo3? 1 MHz C64 (6502 microprocessor), or a 6502 based game console? HH
  2. OK. That's pretty much the what I was expecting the case to be. Thank you. I'm trying to get another PEB to tinker with so I don't have to put the one I have at risk. If I get a /4 and find any further significant differences I'll post them here. HH
  3. I guess I didn't make my question clear. Sorry about that. The mechanical difference on the back of the 99/4 unit might interfere with the use of some boards, which is why I mentioned it. Do those fuses have different capacities, or are they just different form factors? Did they change the power switch because the older one was unreliable? Is the power supply the same, or is one heavier than the other? What I want to ascertain is, will all the same peripheral hardware work in both units? If you plug a Geneve in the 99/4 PEB will it work just the same as if it was plugged into the TI PEB? Will the schematics for one also apply to the other without any changes? (I have only found one set of schematics on-line for the PEB) Are the PC board layouts the same? Can the fire hose cables be swapped between them and both units will still work? In short, if I'm not too late for that, are there any substantive differences? Thanks, HH
  4. I see some mechanical difference on the back of the units. The 99/4 attempts to restrict any external connection to an edge card, or at least an extension to the outside before going to something else. Are there any other differences? HH
  5. I started with a Radio Shack calculator that could not be distinguished from a TI57 if you didn't read the RS model # off of it. It was made by TI for RS. Then I bought the TI58... TRS-80, model I... I also had one to three similar to this, maybe even still have one. 🙂 If I still have it somewhere, I'll bet it still works and I won't have to change the batteries.
  6. Farmer Potato, I went back through that manual and I think you have it right on the execution of LMF. The register field on opcodes >0320 - >033F has just "w" in it. I got it mixed up with the LDD and LDS opcodes which have a "ts" and "s" fields in them. So, presumably, "LMF 3,1" loads data from the addresses of R3-R8, not a *R3 pointer as I indicated above. I think I would rather have it go to *R3, but it doesn't look like it would. I see LMF, LDD, and LDS (the 3 opcodes added to the 990/10 with mapping option) are in the 99105/110 instruction set so anyone who is running a system with one of these could check this for us. Anyone? HH
  7. Is this the Geneve development forum now? I hope I'm not the only one in here that hasn't moved on to the Geneve.😁 I'm still talking about the TI99/4A. I found my own answer at: http://bitsavers.trailing-edge.com/pdf/ti/990/945250-9701_990_Computer_Family_Systems_Handbook_3ed_May76.pdf It's on page 97 at the top. These opcodes at >0320 to >033F come from the TMS990/10. They were added, as an option, to that computer in order to make 1MWords of memory available. The mnemonic for it is LMF. The M bit designates the memory map to load, 0 or 1, and the REG is the register that points to the 6 word map, or source data (SD), to load. X |0 |0 |0 |0 |0 |0 |1 |1 |0 |0 |1 |M | REG | | 0 | 3 | 2 | SD | This is not a TMS9900, nor TMS9995, opcode. On the 990/10+'s LMF is used only when the CPU privilege bit (bit 7,ST) is 0. This was definitely pasted into the E/A manual by mistake. Thanks, HH
  8. I only have TI99/4A consoles. I don't think any of the TI99/4As were made with anything but TMS9900s in them. I am certain that none of mine were. In fact, my recollections are telling me that only the Geneve has the TMS9995, and I don't have one of those.
  9. I also found that the rest of the manual only claims 9 formats. If the opcode shown hadn't fallen so neatly into the empty spot in the opcode map I wouldn't still be looking at it. A 1 rather than a 2? I don't see how myself, unless of course it is a typo as I suggested in my original post. In the book, Editor/Assembler, you can see there are 6 0's, 2 1's, 2 0's, and a 1. That's 11 bits, leaving 5 bits that are designated "REG". Anyone who doesn't have the book can have a look for themselves here: https://archive.org/details/TI994a_Editor_Assembler_Manual/page/n242 There is a single format 10 instruction listed on Wikipedia for the TMS990 called LMF. I'm looking through a manual on the 990 now. I think it's going to be something for the later versions, /10 - /12. I'll post it when I find it.
  10. I was trying to map out the opcodes for the TMS9900 and finally noticed an instruction format X in the E/A manual on page 242. At first I thought it was a typo, that they had left off the preceding "I" for a format IX, but IX is back up on the same line as format III. On closer inspection I found the binary shown, X |0 |0 |0 |0 |0 |0 |1 |1 |0 |0 |1 | REG | | 0 | 3 | 2 | falls neatly into a blank space in the opcode map with its 5 bit wide reg field. In hexadecimal it is >0320 - >033F. I think probably this space is used on another, probably previous, TI processor, and that this table was copied over from a previously published manual, without deleting the unused format X. Does anyone have any knowledge about this? Is there possibly an undocumented opcode in here? Thanks, HH
  11. The "DSK1." part of the file name is the device name. The object code is the device name and file name to which the output of the assembler will be stored. You probably have the option to send that output to an alternate device with Classic99, like "DSK2", "DSK3" or another device supported by the emulator.
  12. The data that he uses for the displayed characters is complete. It is at time index 7:19. Once you have that you would just have to choose positions to put them onto the screen, poll the joysticks and display characters as desired, according to which bits are set.
  13. Maybe you could write the program and send it to him? Then he could make another video with that in it.
  14. There is a listing in the E/A manual on pages 404-406. The description of the ISR, DSR, etc. usage of this memory, as described on these pages, has such a large foot print that I have thrown out any idea of allowing the current interrupt system any access. I don't know of any other list, and I've seen this one referenced every time I've seen the subject come up, as far as I can recall anyway. HH
  15. Since that's exactly what I was looking for I guess it'll have to do. Thank you. HH
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