Lisias

I think I have a working (yet beta, please be patient) solution for searching files from Asimov: http://service.retro.lisias.net/search/ It searches even for filenames (or filename fragments) inside disk images (give it a try using "paravia" on keywords. (feature only available for Asimov at the moment). This thing is running from a bunch of raspberries pi at my living room. Please be patient. :-)

It wasn't my intention to change argument - but I have to admit I could have done a better job at expressing myself in English. Using that EPROM example, I would need 28 (but IIRC it can be done with 27 or 26 if you do some compromise, as keeping the IC on all the time) wires to address 2048 words of 16 bits in a full parallel bus. The CRU does the same with 13, so here is my 13 wires being saved. But by taking another look on it, I realize that in fact I ended up changing my argument... The savings appears to be 15 wires, not 13. :-)

Dude, you need 20 pins to read a 2716 EPROM (2048 x 8 bits) in a parallel bus, plus one /CS to each additional chip hooked on the data bus. To address a 16 bit word using such chips, you'll need an additional 8 wires for the data. The crazy guys from TI reduced it to 13 wires for a whole I/O bus, derived from the TI 990 Mini Computer (where the TMS9900 came from). If you need to reduce your costs on wiring, and don't bother the performance, it fits. So, see you, when the TI-99 came out, they already have a lot of support chips to be used on the computer from the TI 990 era. And, well, some of them was CRU chips. Can't you see the advantage? At least give the TI engineers the benefit of the doubt - these guys were inventing computer architectures 10 years before the 4004, the first micro-processor (and the chip our current status quo derives from). Damn, I wasn't even born when these guys sold their first computer. And, uh, when I talk about I2C and SATA, I was talking about serial buses - I didn't intended to imply that CRU was a 3 pins bus (besides having a 3 pin *data* bus, as the I2C).

It saves 13 long tracks crossing the motherboard to connect the CRU devices, saving board space (and size), reducing routing problems and, so, reducing costs. Not a small thing. 16 and 32 computers became really viable when 3 and 4 layers board became affordable. But on the 2 layered board era, every single track had counted. IBM adopted the 8088 (an 16 bits CPU with 8 bits data bus) on his IBM PC for a good reason. Wiring space was a so big problem in the 70's that Zilog decided to use a 4 bit ALU on the Z'80 to save *DIE* space to be used on more registers and more micro-code. Yeah, Z80 is kind of a 4 bit CPU internally, doing all 8 bit operations in 4 bits chunks. The Z80 would be considerably faster if it had a 8 bit ALU? No doubt about that - you need an 4MHz Z80 to have the same "raw power" of an 2Mhz 6502. But that Z80 would be also prohibitively expensive - so it's hard to tell that Zilog made a bad choice here.

Impossible? Not. But very hard. One need to dissassemble the DSR ROM's module, then change all references from the UCSD Card GROM address to the HSGPL ones, then probably relocate the code to run on some other address (as the Command Module one) with a new banking mechanism (those handling code must replace the original one, by the way) or, alternativelly, relocate it to run on the 32KB memory area (but this will waste precious RAM). There're people doing similar work on other platforms - but granted, it's not trivial work. Far from it.

It's the most elegant solution, but not necessarily the best. The IN/OUT instructions needs 12 t-cycles to be executed, while a simple LD (HL),A takes only 7. Compare them with the 6502's LDA/STA, that takes only 4. If you need performance, you should use memory mapped I/O (or better yet, a DMA controller). Things became better on the R800, that needs only 4 t cycles for IN/OUT and 3 for the LD. (I never understood why Z80 take so long to execute the IN / OUT instructions, I think it should be faster than accessing the memory...)

As a matter of fact, it was one of the best ideas ever. The I²C protocol is doing exactly the same for decades now, and even our current Hard Disks are using serial protocols - SATA. Serial protocols are cheaper (fewer wires across the board/cable) and faster (fewer signals to cause interference each other, so you can speed up things). Of course, if you have space and money to spare, an equivalent 8/16/32 bus at the same speed will be 8/16/32 times faster. But it will occupy 8/16/32 times the board space, and will cause/suffer 8/16/32 times more interference.

Sorry to bring this to the forum. I was cautelous about this issue because I already saw good sites and products being taken down for minor "offenses" - as a spanish ZX Spectrum site that was taken down for publishing screenshots of Spectrum games. (yeah, don't ask - I never understood what happened there). About the ROMs, I almost agree with you : they're (almost of them) available elsewhere. It's perfectly possible to download them, rename them and then repopulate the ROMs directory in order to rebuild the executable. But at least the UCSD Pascal GROMs wasn't so easy to find for me. Ok, perhaps I spent the week looking on the wrong sites, but all I managed to get was the DSR's ROM on whtech. I found this weird, as the disks and manuals are openly redistributed here - so why not the GROMs? Funny enough, I realized I already had that GROMs when I found an old Classic 99' source package. :-) Sorry to bother you with this matter.

I don't know! :-) All I know is what's written on the README.txt on the Classic99's source code. I also found a mention that some "retro computer enthusiast" got a permission to distribute some TIi's ROMs, so it fits. If the guy is overreacting, or he's really protecting his permission, I honestly don't know. ADDENDUM: I talked to a friend of mine, and she explained that Corporations are almost induced to sue any known infringements in order to protect the TRADEMARK, not the product. Old and obsolete products doesn't worths anything in money, but they still have the company's trademark on it. It happens that a trademark can be lost if the owner doesn't sue anyone and everybody that uses it without permission (and, sometimes, even with the permission). I found this about the case: http://www.inta.org/TrademarkBasics/FactSheets/Pages/LossofTrademarkRightsFactSheet.aspx

Unfortunately, the classic99's maintainer took them off the distribution file. He didn't liked the Classic99 source file being used to redistributed the ROMs (as he states on the .txt file on the src/roms directory). Sad. :-( The current version is 274. If I understood correctly, V273 and previous still had the rom files. At least an old package I found here (v365) had them. On the bright side, it appears that I already had the PCode GROMs (, and since I downloaded the 365's package at that time, I think I'm still entitled to had them. However, since the current version don't had it anymore, and since the maintainer doesn't provides old versions, I'm unsure if I can send them to you. The maintainer got a formal authorization to redistribute that ROM binaries, and I'm guessing that is the reason he took them off the source package : to protect that authorization. Well, reverse engineering is protected by law and if you have an UCSD Pascal Card, you're entitled to have a backup copy from it's ROM for personal uses - so you can extract the binary from the executable. It's awkward, but it's easy to do it once you know how. And probably easier than extracting from the GROMs.

In time, I'm experiencing some issues with SCRIBD - the password recovery is not working. On the other hand, I just found the COMPUTE!'s Programmers Reference Guide to TI-99/4A on Archive.org, where many more formats besides PDF are available and without the need of a login/password: https://archive.org/details/COMPUTEs_Programmers_Reference_Guide_to_the_TI-99_4A_1983_COMPUTE_Publications

The Old Computer's page is inaccurate. The BIT-90 had only 2K RAM internally (you will need a external memory expansion for more), and I remember the manual stated something about 1900 bytes free for BASIC programs. It's almost 50% more memory than Old Computer's page states. :-) It's almost nothing, but somehow I managed to make some (silly) two player games (with graphics AND sound!) with so little memory: ignorance is bliss, I didn't knew that 2K is too few memory to make programs! :-) By the way, I'm pretty sure BIT-90 is a unauthorised clone of the Coleco ADAM.

(resurrecting the thread) I had owned a BIT-90 Computer in the early eighties. I had some fun programming it, and had access to the Technical Guide. I don't own it anymore (sadly, really sadly), but I remember some tech specs. May I be of help?

Yes, it works the way you say. Thank you. So the correct URLs become: http://www.nouspikel.com/ti99/pcode.htm http://www.nouspikel.com/ti99/psystem.htm

Hi. The links for the Thierry Nouspikel site are dead. Here follows the currently ones: http://www.unige.ch/medecine/nouspikel/ti99/pcode.htm http://www.unige.ch/medecine/nouspikel/ti99/psystem.htm (edit: See posts below for the correct ones)