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  1. fjkraan

    Another poorly Epson PX-8

    Hi Crashedfiesta, 0.8 is indeed not a standard E-series value. If capacitors are a guide, these come in +/- 20% precision. So 1 mH might work too. It is usally only critically for oscillators. If you order a pack of ten and you have a LC-meter, you might select the one with the least induction...
  2. fjkraan

    Another poorly Epson PX-8

    For me it did work, but charging the pack with a reasonable current (10% of capacity, 14 hours) before putting them in the PX-8 might have helped. Usually I keep the charger connected during prolonged usage. Occasionally I try to develop code for the PX-4/PX8. Greetings, Fred Jan
  3. fjkraan

    Another poorly Epson PX-8

    The original mains adapter for the PX-8 (HOOAAx, where is is a country specific variant) is NOT al power supply, but a battery charger. Power should come from the battery pack. You can operate the PX-8 without the batteries, but voltages get way out of spec. The battery is an integral part of...
  4. fjkraan

    Epson PX-8 / Geneva repair

    If the measured voltage is over the B: and C: ROM sockets, it could be low, as the PX-8 switches the ROM power off when not reading them. Just like modern phones, which are mostly off :-). It is all in the technical documentation: https://electrickery.nl/comp/px8/doc/PX8_TM_Ch2.pdf, page 2-96...
  5. fjkraan

    Another poorly Epson PX-8

    The CAPS LED is switched with CAPS LOCK, the NUM LED with SHIFT-NUMGRPH. I assumed you tried all the reset options: https://electrickery.nl/comp/px8/resetting.txt Greetings, Fred Jan
  6. fjkraan

    Another poorly Epson PX-8

    Hi Crashedfiesta, My first guess based on the earlier screen behaviour is a problematic battery pack or battery connector. You could try a power supply ~ 5V DC connected directly to the main PCB instead of the battery pack and see if it improves things. Greetings, Fred Jan P.S. I do have one...
  7. fjkraan

    Any way to use hex/rom files on a Epson PX-8?

    The ROMs the original author referred to are the 'B:' and 'C:' ROMs of the PX-8. These are 'file-system-ROMs', containing a directory and files, just like a 32kByte sized floppy. Technically they are a switchable part of the 6801 co-processor memory map*. The PX-8 runs CP/M, so all program files...
  8. fjkraan

    TMS7000 development systems

    Hi FarmerPotato, Thanks for the info. I recently tried the EVM and it indeed uses a software UART for the P1 and P2 connectors, to be used for a terminal and a host, or a 'smart'- terminal and a printer. It should be capable of uploading and downloading assembly text and object code. I tried...
  9. fjkraan

    Looking for TMS7000 assembler

    No doubt you've seen the data at http://bitsavers.informatik.uni-stuttgart.de/components/gi/_dataBooks/1982_GI_Microelectronics_Data_Catalog.pdf. It seems the SPR000 is a processor and the SFD2000 the evaluation board with the processor and SP0256. What you are looking for is the "Speech Field...
  10. fjkraan

    Looking for TMS7000 assembler

    Yes, I am interested in the DAISY256 board, but the overseas option is probably best for me. And a fun reason to play with the SPO256. Do you have a reliable source? There appear to be counterfeit for this chip. Greetings, Fred Jan
  11. fjkraan

    E&L MT-80Z (The Fox) trainer board variants

    There appear to be at least three versions of the MT-80Z; a board next to a modified MFP-I MicroProfessor board, an integrated board with most MPF-I components still in place, and an integrated board with the MPF-I components re-arranged. The latter is destined 'MT-80AZ The Fox II'. All appear...
  12. fjkraan

    Any way to use hex/rom files on a Epson PX-8?

    Hi Theancientone, These ROM files, both hex and bin are images with a 32kbyte file system. AFAIK, there is no program or script to copy the files in the image to a PC directory. It is not hard to make, it is just not very often needed. Your options are a FILINK transfer (program on the Util...
  13. fjkraan

    Looking for TMS7000 assembler

    @NobodyIsHere: Thanks for the link. The project is somewhat confusing, as it describes a CTS256 processor based device, but the eprom.asm file contains TMS7000 code and a link to the AS macro & cross assembler source (http://john.ccac.rwth-aachen.de:8000/as/). Is the CTS256 a TMS7k application...
  14. fjkraan

    Looking for TMS7000 assembler

    Hi, Anyone aware of a TMS7000 assembler that uses the syntax of the original Texas Instruments Assembler? The syntax is well described in the 1989_TI_TMS7000_Family_Data_Manual (original at bitsavers, and a version with bookmarks or proper page numbers at...
  15. fjkraan

    TMS7000 development systems

    Thanks for the pointer, the TMS3556 looks like a neat chip and still available 2nd hand. Two boards are designed and ordered so far; a CPU-memory board (RAM&ROM) with the serial port, six 7-segment LED displays & 32 keys pcb. The plan is to create a simple serial monitor for the base board...
  16. fjkraan

    Epson PX-8 Oval Display Adaptor

    Congratulations! It is exiting when someone can reproduce something I cobbled together. Greetings, Fred Jan
  17. fjkraan

    TMS7000 development systems

    Most of the documents are scanned and available at https://electrickery.nl/comp/tms7k/doc. The main page is still incomplete. Greetings, Fred Jan
  18. fjkraan

    TMS7000 development systems

    Hi jbdigriz, Thanks for the response and the pointers, I will investigate those. For scanning, I'll start with the stuff not found elsewhere. In the mean time I only managed to start up the Evaluation Module (it works!) and dump its ROMs (included here as I didn't create a page for this...
  19. fjkraan

    new PDP QBUS panel project

    Before I decided to use the PX0-600, I was thinking about using a 2457600 Hz crystal and a 74HC4060, divide by 8192 to 300 Hz. Then a selectable division by 5 or 6 (could be a 7490) to get 60 or 50 Hz. Would have been an option for the second version of the LTC board which never happened. Fred Jan
  20. fjkraan

    new PDP QBUS panel project

    Some info (text, no diagram) can be found in this document, page 1-5: EK-MIC11-TM-002_MicroPDP11_Systems_Technical_Manual_Sep85.pdf. The schematic referred above was derived (IIRC) from a PDP-11/03 schematic which I redrew in KiCAD with added the PX0-600 part. I use an ATX-power supply, so the...
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